CN110803812B - High-salinity high-nitrate industrial wastewater treatment method and system - Google Patents

Abstract

The invention relates to a high-salinity and high-nitrate industrial wastewater treatment method and a high-salinity and high-nitrate industrial wastewater treatment system, wherein the treatment method comprises the steps of neutralization and desalting in pretreatment, nitrate nitrogen removal through electroreduction, ammonia nitrogen removal through chlorine absorption and chlorine generation through electrooxidation, so that treated water samples are sequentially circulated and mutually coupled among treatment programs in each step, and two treatment systems for treating high-salinity and high-nitrate industrial wastewater by means of three characteristic cycles, namely sodium cycle, chlorine cycle and alkali cycle are provided; a series of criterion parameters, standards, methods and three control equations are provided, and the addition, preparation and accurate feeding of relevant medicaments are quantitatively guided from the aspect of parameter control, so that the effective treatment of a treated water sample in each step and the sequential coordination and stable circulation among treatment programs in each step are realized, the completion of a nitrate removal task is ensured, the excess alkali production capacity in the conversion process can be fully utilized and consumed, the excessive use and waste of medicaments can be avoided, and the maximum limit on the content of the final effluent hypochloride can be realized.

Description

High-salinity high-nitrate industrial wastewater treatment method and system

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a high-salinity high-nitrate industrial wastewater treatment method and system.

Background

At present, the discharge of wastewater containing nitrate becomes one of the important sources of water environment pollution, especially high-salinity and high-nitrate industrial wastewater, because the wastewater has the characteristics of large quantity, high concentration, complex water quality and the like, the serious impact on the environmental water quality can be caused by the large-quantity and concentrated discharge of the wastewater. However, so far, no economic and effective treatment method for the wastewater is found, so that the pollution of nitrate water bodies is more serious, and related enterprises face the threats of production limitation and production halt in areas with tightened emission standards and strengthened emission control, so that the local economic development is influenced.

The traditional treatment method of the wastewater containing the nitrate comprises a physical method, a chemical method, a biological method and a combined treatment method thereof. Physical methods include electrodialysis, reverse osmosis, ion exchange, etc., but the only treatment result of physical methods is the transfer of nitrate, which does not address its ultimate destination. Chemical methods often involve the addition of highly chemically active reducing agents, require high raw material costs, and often involve the formation of other products, thereby causing secondary pollution. The biological denitrification technology is only effective for a few specific water samples, but is basically ineffective for high-salinity and high-nitrate wastewater. Denitrifying bacteria are difficult to survive in a high-salt environment, the denitrifying effect needs a carbon source to provide nutrition, and the biological method often has the defects of low treatment efficiency, poor impact resistance to treatment load change and the like.

Besides the traditional treatment method, a later-developed electrochemical treatment method is provided, and the method is mainly a treatment scheme aiming at the pollution of a drinking water source. The main technology is to use a two-chamber electrolytic cell to rotate the water sample from the cathode to the anode and add chloride in the anode chamber to promote the final conversion of nitrate nitrogen to nitrogen. The nitrate-containing drinking water has simple quality and small nitrogen removal load, so the treatment of the drinking water by the above technology is not high in economic and environmental acceptable difficulty. However, this simple electrochemical technique becomes insufficient in the case of high-salinity high-nitrate wastewater. The main reasons are three points: firstly, the cost is increased and the salinity of effluent is increased due to the addition of a large amount of chloride, and the subsequent microbial treatment of trace residual nitrate is more unfavorable due to the increase of the salinity; secondly, indissolvable substances formed in the electrochemical conversion process are stuck to the reactor; thirdly, the discharged chlorine gas pollutes the air.

The literature of the prior art discloses that a second electrochemical treatment scheme has also been proposed for nitrate-containing wastewater, in which a single-chamber electrolysis is carried out in a common cathode and anode, and no sodium chloride or potassium chloride is added during the electrolysis process. The main advantages of the scheme are simple structure of the electrolytic cell, zero salt consumption and simple process, but the main disadvantages are high electrolytic voltage, large electrolytic energy consumption, low nitrogen removal efficiency and serious interaction influence of cathode and anode reactions. The comprehensive treatment cost is high, the treatment difficulty is high, the treatment speed is low, the treatment effect is poor, and the applicability of the second scheme to the treatment of the high-salt and high-nitrate industrial wastewater is lower than that of the first scheme.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a high-salinity high-nitrate industrial wastewater treatment method and system. The treatment method adopts three characteristic cycles of sodium cycle, chlorine cycle, alkali cycle and the like coupled with electrochemical denitration, a chlorine absorption water inlet alkalinity control equation, an electrooxidation water inlet water chlorine strength control equation, an anode alkali matching strength control equation and the like, fully utilizes the alkali outlet capacity of electrochemical reaction during the denitration to remove metal ions capable of forming hydroxide precipitates, avoids the discharge of chlorine while removing ammonia nitrogen by using the chlorine, and can stably operate even without consuming and supplementing the sodium chloride although the sodium chloride is used.

A high-salt and high-nitrate industrial wastewater treatment method comprises the following steps in a stable stage:

(1) and (3) carrying out electro-reduction for removing nitrate nitrogen:

nitrate radical in the waste water is subjected to electro-reduction reaction in an electrochemical reactor to generate N₂And NH₄ ⁺And simultaneously also by-product H₂And OH^-；

(2) Chlorine gas absorption and ammonia nitrogen removal:

using OH generated in step (1)^-Absorb chlorine and react on NH₄ ⁺Chemical oxidation is carried out to generate N₂And Cl^-(ii) a (3) Electrooxidation to evolve oxygen and chlorine:

utilizing Cl generated in step (2)^-And OH produced in step (1)^-Carrying out electro-oxidation reaction to generate chlorine and oxygen, and returning the chlorine to the step (2) for absorption;

preferably, the method further comprises a pretreatment step for desalting or adjusting alkalinity.

Preferably, the desalting or alkalinity adjustment is performed using the alkali produced in step (1).

The basis of the high-salt and high-nitrate industrial wastewater treatment method is related to electrochemical reaction and chemical reaction. The pretreatment is simple acid-base neutralization reaction and precipitation reaction combining metal ions and hydroxide ions. The electro-reduction treatment relates to electro-reduction conversion of nitrate ions, and the conversion process is also a high-efficiency alkali production process. The end products of the removal of nitrate ions by cathodic electrochemical reduction are nitrogen and ammonium ions, accompanied by the production of significant amounts of hydroxide ions, as shown in formulas 1) and 2).

NO₃ ^-+3H₂O+5e^-→0.5N₂+6OH^- 1)

NO₃ ^-+7H₂O+8e^-→NH₄ ⁺+10OH^- 2)

Nitrite ions are also formed during the conversion of nitrate to nitrogen and sodium ions, as shown in equation 3), which is an intermediate product of the conversion of nitrate ions to nitrogen and ammonium ions, and if the electrochemical conversion is not complete, a small amount of nitrite ions will be present in the conversion product.

NO₃ ^-+H₂O+2e^-→NO₂ ^-+2OH^- 3)

Due to the difference of cathode catalyst selectivity, the difference of nitrate ion concentration, the difference of water quality and environment and the difference of electrolytic cell tank pressure, the electrochemical reduction process of nitrate ions is accompanied by the precipitation of hydrogen by-products with different proportions, and the precipitated hydrogen is also accompanied by the generation of hydroxide ions, as shown in formula 4).

2H₂O+2e^-→H₂+2OH^- 4)

The electro-oxidation treatment involves electro-oxidation reaction of chloride ions and hydroxide ions to generate chlorine gas and oxygen gas, respectively, as shown in formulas 5) and 6).

2Cl^-→Cl₂+2e^- 5)

4OH^-→O₂+2H₂O+4e^- 6)。

Chlorine gas absorption relates to chlor-alkali chemical reaction and chemical oxidation reaction of ammonium ions, and chlorine gas precipitated in the electro-oxidation treatment is absorbed by alkali in electro-reduction effluent and is used for carrying out chemical oxidation on the ammonium ions in the electro-reduction effluent. The products of the chemical oxidation of ammonium ions by chlorine gas are nitrogen and chloride ions, as shown in formula 7). The absorption of chlorine and the oxidation of ammonium ions are mostly accomplished by the intermediate product of hypochlorous acid and ions, and formula 7) shows an integrated process. When chlorine gas is absorbed by the alkaline water, hypochlorite ions are generated if the supply of chlorine gas is excessive in comparison with the need for oxidation removal of ammonium ions, as shown in formula 8).

1.5Cl₂+4OH^-+NH₄ ⁺→3Cl^-+0.5N₂+4H₂O 7)

Cl₂+2OH^-→Cl^-+ClO^-+H₂O 8)。

The invention relates to a plurality of terms, and related proprietary terms and meanings and expression symbols thereof are shown in table 1. See tables 2-4 for values of relevant parameters.

In the treatment technology, the invention adds two treatment procedures of pretreatment and chlorine absorption besides necessary electro-oxidation and electro-reduction so as to synergistically complete the treatment of the high-salinity and high-nitrate industrial wastewater. The coupling design of the four-step processing program and the sequential circulation of the processed water samples provide basic hardware conditions for the realization of three characteristic cycles. In addition, the invention also provides and applies a series of criterion parameters, a criterion, a discrimination method and three control equations to provide necessary software support for realizing three characteristic cycles. The discrimination parameters, the discrimination standards, the discrimination methods and the three control equations are used for guiding the effective treatment of each step of the treated water sample and the sequential coordination treatment and circulation among four-step treatment programs, thereby ensuring the completion of the denitration task, fully utilizing and eliminating the excess alkali production capacity in the conversion process, avoiding the excessive use and waste of medicaments and simultaneously realizing the maximum limit on the content of the final effluent hypochloride.

The three cycles are sodium cycle, chlorine cycle and alkali cycle, respectively. Sodium circulation means that sodium ions migrate upstream from an anodic electrooxidation water sample to a cathodic electroreduction water sample through a cationic membrane in the electrochemical conversion process, and then migrate downstream from the cathodic electroreduction water sample to the anodic electrooxidation water sample through water sample circulation; the sodium cycle matches the upstream electroreduction alkali production requirements and the downstream chlorine absorption and anodic electrooxidation alkali requirements. Chlorine circulation means that chlorine ions are converted into chlorine atoms in the anodic electrooxidation process and form chlorine gas which is separated out from a water sample, the generated chlorine gas is absorbed by the cathodic electroreduction alkaline effluent and reacts with ammonium ions so as to be converted into chlorine ions, and the chlorine ions are transferred to the electrooxidation treatment water sample along with the treatment water sample; if the chlorine generating capacity of the anode through electrooxidation is excessive, part of chlorine can not be completely converted into chloride ions after being absorbed by the alkali liquor. The alkali circulation refers to that part of the electrically reduced alkaline effluent is reused in a pretreatment procedure, the alkalinity of the effluent is used for neutralizing and desalting raw water, the pretreatment step is completed, the effluent is transferred to an electrical reduction treatment step, and the alkalinity of a circulating water sample is recovered after electrochemical treatment; whether or not the caustic recycle is employed will depend on the caustic capacity and the need for pretreatment.

The criterion parameters include electromigration degree C_Na+Ability to produce ammonium C_NH4+Maximum excess alkalinity C^* _YJAbility to give out alkali C_SRStrength of chlorine production C_ClEffective chlorine degree C^* _Cl-Highest anode base strength C^* _AJThe anode alkali-distribution strength underamount x, and the like, and the judgment standards and the judgment methods are shown in tables 2 to 4. The first of the three control equations is the control equation for the alkalinity of the chlorine absorption feed water, i.e., C_XJ＝C^* _YJ+4C_NH4+The second is the chlorine intensity control equation for the electrooxidation feed water, i.e. C_Cl＝C^* _YJ+3C_NH4+-C_YJ(0≤C_YJ≤C^* _YJ). The two control equations are used for controlling the feeding intensity and the batching intensity (the feeding is based on raw water and derivatives thereof, the batching is based on external water samples, the relevant criterion parameters, the discrimination standard and the two control equations are used, and the properties, the quantity, the feeding place and the timing of the pre-treatment feeding agent are determined by combining the raw water properties, the treatment requirements and the equipment capacity, whether the electro-reduction effluent is recycled, the lower limit of the recycling proportion and the like are determined, so that not only can the sufficient supply of chlorine be ensured, but also the surplus of the chlorine can be prevented, the ammonia nitrogen can be ensured to be removed, and the chlorine emission is not caused, one of the two control equations is a control index of the highest residual alkalinity found and defined by the invention, the index of the alkali production capacity deduction can be used for measuring the alkali production capacity of the treatment system, and the index can be used for ensuring the removal of the ammonia nitrogen and the alkali production capacity exceeds the alkali production capacity, the method can be used for alkali extraction, otherwise, alkali supplement is needed before chlorine absorption. The highest residual alkalinity ensures the chlorine circulation for removing ammonia nitrogen, and theoretically ensures that the chlorine circulation can be realized without adding sodium chloride in a stable stageThe ammonia nitrogen is completely oxidized and removed by chlorine.

The chlorine cycle is used for keeping zero salt replenishment and ammonia nitrogen removal, and besides the highest residual alkalinity is needed for control, the highest anode alkali-blending intensity index is also needed to be used, which is reflected in a third control equation, namely an anode alkali-blending intensity control equation: c_AJ＝C*_AJ–x(C*_AJ＝(1+r)C*_YJ+3rC_NH4+). The related criterion parameters, the discrimination standard and the third control equation can be used for determining or controlling parameters such as the anode alkali blending strength in the starting stage, the anode salt blending strength in the starting stage, the residual alkalinity in the second control equation, the hypochlorite content of the final effluent and the like. According to the third control equation, when x is 0, theoretically, the required chlorine cycle can still be maintained, ammonia nitrogen is completely oxidized, no chlorine gas is discharged, effluent has no hypochlorite ions, and zero salt supplement is stably operated. In addition, although x is 0, the ammonia nitrogen is not oxidized completely in practice although the ideal dosing condition is provided, so that a non-zero anode alkali dosing intensity scheme is recommended in the practical operation process.

The comprehensive treatment method of the high-salinity and high-nitrate industrial wastewater with electrochemical treatment as a core comprises two operation modes of equal-volume batch treatment and constant-flow continuous flow, wherein each mode comprises two operation stages of starting and stabilizing. For any phase of the operation in any mode, the coulomb intensity formula for electrochemical treatment remains the same, as shown in table 1. The electric power intensity is based on the load of raw water treatment when electrochemical treatment is being performed.

According to the characteristics of salt content in raw water, the raw water is divided into a zero-desalting-load water sample and a non-zero-desalting-load water sample, wherein the former means that the raw water does not contain metal ions capable of forming hydroxide precipitates, the latter means that the raw water contains metal ions capable of forming hydroxide precipitates, and the so-called desalting load means the sum of equivalent molar concentrations of all metal ions capable of forming hydroxide precipitates contained in the raw water. The number of the zero-desalting load water samples is three, as shown in sequence 1, 2 and 3 in table 2, and the number of the non-zero-desalting load water samples is four, as shown in sequence 1, 2, 3 and 4 in table 3.

The comprehensive treatment method of the high-salinity high-nitrate industrial wastewater provided by the invention comprises four steps of treatment in a stable operation stage: desalting or alkalinity adjustment in pretreatment, nitrate and nitrogen removal by electroreduction, ammonia nitrogen removal by chlorine absorption, and oxygen evolution and chlorine evolution by electrooxidation. Some raw water does not need a pretreatment process, but it is also regarded as a four-step treatment in the present invention, except that the pretreatment step is omitted in the treatment process. The four-step process of the stabilization phase is applicable to either mode of operation. The raw water treatment load of the isometric batch operation mode in the stable stage is Q liters per batch, and the raw water treatment load of the constant flow continuous flow operation mode in the stable stage is Q liters per hour.

According to the difference of the pretreatment characteristics in the stabilization stage, the invention divides the raw water into three types and seven types. The first type is called type A, and the water sample can directly enter an electroreduction treatment stage without any pretreatment; only one such water sample, shown in sequence 1 of table 2, is a zero desalination load water sample. The second type is called B type, and the two types are shown in the sequences 2 and 3 in the table 2, and the water samples belong to water samples with zero desalting load, the pretreatment of the water samples only needs to be supplemented with acid or alkali for alkalinity adjustment, and the supplementing strength is shown in the table 2. The third type is called C type, and the total number is four, as shown in the sequence 1, 2, 3 and 4 in the table 3, the three belong to non-zero desalting load water samples, and the common characteristic in the pretreatment is that the downstream electroreduction water outlet part is required for recycling, and the alkali or acid supplementation conditions are different; the feeding strength and recycling characteristics of various water samples contained in class C during pretreatment are shown in Table 3. The alkali-supplementing agent during alkali supplementation is sodium hydroxide, and the acid-supplementing agent during acid supplementation is hydrochloric acid. The pretreatment serves two purposes, namely, reducing the concentration of metal ions of the formed oxide precipitates to zero or the extent that the metal ions are not deposited in an electrochemical reactor, and pre-adjusting the alkalinity so as to ensure that the alkalinity of the downstream electroreduction effluent reaches the specified requirement. For the second purpose, the acid-supplementing regulation and/or partial alkali-supplementing load in the pretreatment of part of the water sample can be completed after the downstream electroreduction is completed.

The second step of electroreduction treatment is to carry out electrochemical reduction denitration treatment on the pretreated effluent, so that nitrate ions are converted into nitrogen and ammonium ions, if the electroreduction conversion selectivity is not ideal, part of nitrate ions are converted into nitrite ions, the conversion process is accompanied with the generation of hydrogen evolution side reaction, and the nitrogen and the hydrogen are evacuated; the electroreduction treatment and the downstream electrooxidation treatment are carried out in a matching way, the nitrate removal process is also an alkali production process, one part of sodium ions required by alkali production is obtained by electromigration from an electrooxidation water sample, the other part of sodium ions is provided by upstream alkali supplement, the other part of sodium ions comes from the original water, and if the original water contains potassium ions, the original water is also considered as a sodium ion source; after the denitration is finished, (1+ r) Q liters of water are discharged in each batch or each hour (when the water return is not needed, the water is regarded as r ═ 0), wherein rQ liters of water are recycled for pretreatment in each batch or each hour, and the residual water (neglecting the influence of electromigration on the water quantity) enters the downstream chlorine absorption.

The third step is to absorb chlorine gas by using the alkaline effluent from the second step of treatment and convert ammonium ions in the water sample into nitrogen gas, wherein the chlorine gas carries oxygen, and the mixed gas comes from downstream electrooxidation treatment; and the residual oxygen of the mixed gas after the chlorine is absorbed and the newly generated nitrogen form anode tail gas of the treatment system to be discharged. The fourth step is to carry out electrooxidation treatment on the water sample which is transferred from the third step, oxygen is produced and chlorine is produced in the electrooxidation process, and the produced gas returns to the upstream to participate in the treatment of absorbing chlorine and removing ammonia nitrogen; the electro-oxidation treatment is paired with an upstream electro-reduction treatment and is supplied with part of the sodium ions required for alkali production by electromigration. The salt supplement of the water sample before electro-oxidation treatment can be carried out according to the stable salt supplement strength of the anode during salt supplement, and the salt supplement agent is sodium chloride as shown in table 4; the salt replenishment operation may be performed at any time prior to the electro-oxidation treatment (even during the pretreatment stage), not just prior to the electro-oxidation treatment. And forming final effluent after the fourth step of treatment, wherein the content of hypochlorite ions in the effluent can be zero or not.

The isometric batch processing mode of the stable stage has the characteristic of periodic operation, four water samples exist simultaneously and are in different processing states in one processing period, and six water samples are counted in the four processing states, raw water and final effluent; carrying out electro-oxidation treatment on the nth water sample and electro-reduction treatment on the (n + 2) th water sample in a matched mode; after one treatment period is finished, the electrooxidation effluent becomes final effluent, the chlorine absorption effluent, the electroreduction effluent and the pretreatment effluent are sequentially converted into electrooxidation influent, chlorine absorption influent and electroreduction influent of the next treatment period, and the pretreatment influent of the next treatment period is a new batch of raw water. The constant flow continuous flow mode in the stable stage has the characteristic of stable and continuous operation, a stable water flow is formed from raw water to final effluent, the water flow is subjected to four treatment procedures of pretreatment, electro-reduction denitration, chlorine absorption denitration and electro-oxidation chlorine generation denitration in sequence, wherein the electro-reduction denitration and the electro-oxidation chlorine generation are carried out in a pairing mode.

The water samples in different treatment states in the stable stage are all raw water derivatives and the downstream treatment program can provide cooperation for the upstream program, but before the stable stage is reached, the downstream treatment program is lack of raw water derivative samples, so the main task of the start-up stage is to prepare raw water derivative samples which can be matched with the upstream treatment for the downstream treatment and meet other conditions required for reaching stable operation. The operation in the start-up stage is greatly different depending on the kind of raw water and the operation mode.

In terms of an equal-volume batch processing operation mode, two times of electrolysis are required to be performed in a starting stage, the water volume of a cathode water sample used in each time of electrolysis is (1+ r) Q liters, the water volume is provided by pretreating (1+ r) Q liters of raw water according to initial feeding strength shown in tables 2 and 3 and a pretreatment program in a stable stage, the water volume of an anode water sample used in each time of electrolysis is Q liters, and alkaline saline water obtained by preparing pure low-hardness water samples such as Q liters of deionized water or purified water according to anode salt mixing strength and anode alkali mixing strength shown in tables 2 and 3 is provided as a dosing agent, wherein the dosing agent is sodium chloride and sodium hydroxide. And (3) exhausting gas generated by the anode in the first electrolysis process, not executing chlorine absorption, wherein Q liters in cathode effluent after the first electrolysis is finished is used for chlorine absorption for the first time, the chlorine absorption for the first time and the second electrolysis are simultaneously carried out, the residual rQ liters are used for pretreatment of a third batch of raw water, and the treated water amount is Q liters. And replacing the effluent after the first chlorine absorption with prepared alkaline brine as an anode water sample for third electrolysis, using Q liters in the cathode effluent after the second electrolysis as a water sample for second chlorine absorption simultaneously with the third electrolysis, using the residual rQ liters for pretreatment of a fourth batch of raw water, wherein the treated water amount is Q liters, and then, entering a stabilization stage in the treatment process.

For the constant flow continuous flow operation mode, the operation principle of A, B two types of three water samples in the start-up phase is basically the same, while the C type of four water samples are different from the former two types. For A, B two types of three water samples, the start-up stage needs to perform water quality state control, flow stability control and water sample switching. The pretreatment procedure and the batching parameters for providing the cathode water sample for electrolysis in the starting stage are the same as those in the stabilization stage, the anode water sample during electrolysis treatment in the starting stage is alkaline saline water, the flow of the anode water sample is equal to the load of raw water for batch treatment, the anode water sample is prepared by adding sodium chloride and sodium hydroxide into pure low-hardness water samples such as deionized water or purified water according to the anode alkali-blending strength and the anode salt-blending strength, and the batching strength is shown in tables 2-4. The current processing can provide a constant-flow cathode water sample for the electrolysis process, the anode prepares alkaline saline water and can start electrolysis when providing a constant-flow anode water sample for electrolysis, the water quality of cathode electroreduction effluent water starts to be conveyed to the downstream after meeting the processing requirement, the chlorine absorption operation starts when the water flow can provide constant-flow supply for chlorine absorption, the water flow after the chlorine absorption can provide a constant-flow anode water sample for electrolysis, the prepared alkaline saline water flow is replaced by the water flow, the starting stage is ended at the moment, and the steady-state stage starts. And in the stable stage, anode salt supplement is needed, and sodium chloride is supplemented before or after the chlorine is absorbed or in the absorption process according to the anode stable salt supplement strength shown in the table 3.

Compared with the A, B start-up of the two-class three-water sample in the constant flow continuous flow operation mode, the start-up of the four-class C-water sample treatment has three more switches, namely the switch of the pretreatment program and the load, the switch of the cathode water sample and the switch of the electrolysis treatment load. The treatment of four water samples of class C in constant flow continuous flow mode of operation also starts with the preparation of water samples of the cathode and anode: the effluent after the raw water is pretreated according to the initial alkali-supplementing strength and the initial acid-supplementing strength shown in table 3 is a cathode water sample, and the alkaline brine obtained by preparing a pure low-hardness water sample such as deionized water or purified water according to the anode salt-blending strength shown in tables 3 and 4 is an anode water sample. When the cathode water sample can meet the supply speed of (1+ r) Q liter per hour and the anode water sample can meet the supply speed of Q liter per hour, the electrolysis is started, when the quality of the cathode effluent meets the requirements of electroreduction treatment, the cathode effluent is supplied to the downstream, when the cathode effluent can provide Q liter per hour and the anode effluent can provide constant flow continuous supply of rQ liter per hour for pretreatment, the chlorine absorption is started and the reuse water is provided for the pretreatment, and if the anode salt supplement is needed in a stable stage, the sodium chloride is supplemented according to the anode stable salt supplement strength before or after the chlorine absorption or in the absorption process. When the effluent water flow after chlorine absorption (and salt supplementation) reaches the inlet of the anode chamber and can provide constant flow for anodic electrooxidation, the effluent water flow is discharged according to the constant flow of Q liters per hour until the load of cathodic electrolysis treatment starts to be switched. After the cathode electroreduction effluent is recycled and started, the raw water is pretreated by using the water flow according to the stable feeding intensity shown in the table 3 until the pretreatment effluent speed can provide (1+ r) Q liters per hour of constant flow for continuous water flow output to the downstream, and the new water flow replaces the original pretreatment effluent without the participation of the cathode effluent and is conveyed to the downstream. When new water flow reaches an inlet of the cathode chamber, the water flow of the anode chamber is immediately switched from the prepared alkaline saline water to the raw water derivative after chlorine absorption and salt supplementation, meanwhile, the electrolysis treatment load is switched from (1+ r) Q liter per hour to Q liter per hour, the water supply of cathode and anode effluent to the downstream is suspended, when the water quality of the cathode effluent meets the treatment requirement, the constant-flow supply of the cathode and anode effluent to the downstream is resumed, and then the system enters a stabilization stage.

TABLE 1-terms and meanings

TABLE 2-treatment operating parameters and effluent hypochlorous strength of zero-desalination load water samples under control of trona

TABLE 3 treatment operating parameters and effluent hypochlorous strength under trona control for non-zero desalted loaded water samples

Table 4-Table 2 and Table 3 show the anode ingredient supplement condition and the effluent hypochlorous intensity (anode salt-complex intensity C) of any water sample under the conditions of rich salt and insufficient alkali at the anode_AY≥x+3CNH₄ ⁺)

The system for implementing the high-salinity and high-nitrate industrial wastewater treatment method comprises two operation systems, namely an equal-volume batch treatment system and a constant-flow continuous flow system.

The invention provides an isometric batch processing system which comprises a pretreatment system, an electrochemical treatment system and a chlorine absorption system; the pretreatment system comprises a neutralization and sedimentation tank, a filter and a water storage tank; the electrochemical treatment system comprises a direct current power supply, an electrochemical reactor, a cathode circulating tank and an anode circulating tank; the electrochemical reactor comprises a cathode chamber and an anode chamber, a cathode circulating pump is arranged on a pipeline between the cathode chamber and the cathode circulating tank, and an anode circulating pump is arranged on a pipeline between the anode chamber and the anode circulating tank; the cathode chamber, the cathode circulating tank, the cathode circulating pump and relevant circulating pipelines form an electroreduction treatment circulating system; the anode chamber, the anode circulating tank, the anode circulating pump and relevant circulating pipelines form an electro-oxidation treatment circulating system;

the equal-volume batch processing system is driven by a cathode circulating pump and an anode circulating pump, and completes electrochemical processing of a water sample and circulation between different processing procedures by combining switches of relevant valves.

The cathode chamber and the anode chamber of the electrochemical reactor are formed by being separated by a cation membrane.

The chlorine absorption system includes a chlorine absorption tank.

A material supplementing port is arranged above the neutralization precipitation tank;

a material supplementing port is arranged above the water storage tank;

and a material supplementing port is arranged above the cathode circulating tank.

And a salt supplementing port is arranged above the anode circulating tank.

The invention also provides another system for implementing the high-salinity high-nitrate industrial wastewater treatment method, which is a constant-flow continuous flow system, wherein the constant-flow continuous flow system comprises a pretreatment system, an electrochemical treatment system and a chlorine absorption system; the pretreatment system comprises a neutralization and sedimentation tank, a filter and a water storage tank; the electrochemical treatment system comprises a direct-current power supply, an electrochemical reactor, a cathode gas-liquid separation tank, an anode tail gas separation tank and an anode gas-liquid separation tank; the electrochemical reactor comprises a cathode chamber and an anode chamber, a cathode water inlet pump is arranged between the water storage tank and the cathode chamber, and an anode starting water inlet pump is connected with an inlet of the anode chamber; the upstream and the downstream of the cathode chamber are respectively connected with an outlet of a cathode water inlet pump and an inlet of a cathode gas-liquid separation tank, and the upstream and the downstream of the anode chamber are respectively connected with an anode tail gas separation tank and an anode gas-liquid separation tank; the chlorine absorption system includes a chlorine absorption tank.

The cathode gas-liquid separation tank is a high-level tank, a cathode gas discharge port and a first water sample inlet are arranged at the top of the cathode gas-liquid separation tank, and the first water sample inlet is connected with an outlet of the cathode chamber; the bottom of the cathode gas-liquid separation tank is provided with a first water sample outlet, and the water sample outlet is connected with a tee joint and respectively communicated with the neutralization precipitation tank and the chlorine absorption pipe inlet; and a first starting overflow pipe is arranged at the upper part of the cathode gas-liquid separation tank.

The anode tail gas separation tank is a meso-position tank, the top of the anode tail gas separation tank is provided with a second water sample inlet, a salt supplementing pipe and an anode tail gas discharge port, and the second water sample inlet is connected with the outlet of the chlorine absorption pipe; the salt supplementing pipe is inserted into a water sample in the tank; the bottom of the anode tail gas separation tank is provided with a second water sample outlet which is connected with the inlet of the anode chamber; and a second starting overflow pipe is arranged at the upper part of the anode tail gas separation tank.

The upstream and the downstream of the chlorine absorption pipe are respectively connected with the outlet of the cathode gas-liquid separation tank and the second water sample inlet of the anode tail gas separation tank; the chlorine absorption pipe is also provided with a gas inlet, and the gas inlet is connected with a gas outlet of the anode gas-liquid separation tank.

The constant flow continuous flow system respectively completes the flow circulation of a cathode water sample and the flow of an anode water sample by using a cathode water inlet pump and an anode water inlet pump in a starting stage, and completes the flow and circulation of a treated water sample in the system by using only one cathode water inlet pump in a stable stage.

The constant flow continuous flow system uses two start-up overflows in the start-up phase to control and direct the constant flow and circulation of the treated water samples between the relevant intermediate treatment steps.

The invention has the beneficial effects that:

(1) the high-salinity and high-nitrate industrial wastewater treatment method comprises the steps of pretreatment desalting or alkalinity adjustment (which can be omitted), electroreduction denitrogenation, chlorine absorption ammonia nitrogen removal and electrooxidation chlorine generation when the high-salinity and high-nitrate industrial wastewater treatment method is in a stable stage, so that treated water samples are sequentially circulated and mutually coupled among treatment programs of the steps, and a hardware basis for solving the treatment of the high-salinity and high-nitrate industrial wastewater by means of three characteristic cycles (sodium cycle, chlorine cycle and alkali cycle) is established.

(2) The invention provides three key parameter control technologies such as a chlorine absorption water inlet alkalinity control equation, an electrooxidation water inlet chlorine strength control equation, a starting stage anode alkali distribution strength control equation and the like, and the internal correlation among all the operation parameters is quantitatively solved by taking the three control equations as guidance, so that the benign correlated stable operation of three characteristic cycles is ensured in the aspect of parameter control (in the aspect of software).

(3) The invention discovers the highest residual alkalinity C^* _YJThis key index, and use formula C^* _YJ＝C_Na+-3C_NH4+The balance obtained by subtracting the triple ammonium production capacity from the electromigration degree quantitatively expresses the complex internal relationship between the index and the water quality of raw water, the treatment requirement and the equipment capacity, theoretically clears various related factors influencing the highest residual alkalinity, and defines the quantitative contribution of each influencing factor to the highest residual alkalinity.

(4) The invention can produce alkali C_PJDeducting maximum excess alkalinity C^* _YJThe balance of (A) is used as a measure of the alkali discharge capacity C of the treatment system_SRThe indexes of the method are used for accurately classifying and planting various water samples to be treated by combining the alkali discharge capacity with the desalting load so as to provide corresponding treatment strategies aiming at various conditions, thereby solving the problem of contradiction balance between the alkali discharge capacity and the desalting requirement in an optimal mode and an optimal effect.

(5) The highest anode alkali-blending intensity C in the starting stage is used in the invention^* _AJ(C^* _AJ＝(1+r)C^* _YJ+3rC_NH4+Maximum value of anode base-added intensity) to quantify the anode salt-added intensity C_AYAnd anode alkali-complex strength C_AJThe contradiction between the two is unified, the problem of downstream coordination required by upstream water sample treatment before the raw water derivative reaches the downstream treatment program in the starting stage is solved, and the problem of downstream coordination required by the downstream treatment in the starting stage is solvedSmooth transition from the segment to the stabilization phase.

(6) The invention uses the electric quantity intensity and the processing load to standardize the electrochemical processing load required by the high-salinity high-nitrate wastewater processing, and highlights the key electrochemical parameters required by the high-salinity high-nitrate wastewater processing. The two parameters are used for replacing traditional electrochemical parameters such as voltage, current, time and the like, so that the treatment method is not limited by the specific performance of the electrochemical reactor, the treatment method is focused on the electrochemical core operation parameters, and the universality of the treatment method is improved.

(7) The solution provided by the invention covers the ideal use condition and the actual use condition of the sodium chloride, unifies the ideal use condition and the actual use condition, not only exerts the medium function of the sodium chloride to the maximum extent, but also avoids the excessive use and waste of the sodium chloride, and simultaneously considers the wastewater removal treatment and the environmental protection. The treatment scheme can ensure that the chlorine gas required by ammonia nitrogen removal is sufficiently supplied, can prevent the excess of chlorine gas productivity, can ensure the removal of ammonia nitrogen, and does not cause the discharge of chlorine gas. Ideally, no sodium chloride is added during the stabilization phase and the effluent contains no hypochlorite ions.

(8) The invention provides two operation modes of constant-flow continuous flow and equal-volume batch processing and a corresponding processing system, and the processing method can be grounded to take care of various actual processing tasks.

(9) The invention provides a plurality of switching operations or replacement processing for transition from a starting stage to a stable stage, provides a measure for meeting various conditions required for reaching a switching state or replacement operation, provides control measures and judgment bases of various switching/replacement nodes, and provides a practical solution for reaching a stable running state in a processing process.

Drawings

FIG. 1 is a schematic structural view of a basic unit of an electrochemical reactor according to the present invention;

FIG. 2 is a schematic diagram of the steady-state treatment process of the high-salinity and high-nitrate industrial wastewater treatment according to the invention;

FIG. 3 is a schematic diagram of the construction of an isometric batch system of the present invention;

FIG. 4 is a schematic diagram of a constant flow continuous flow processing system according to the present invention.

Wherein the reference numerals are as follows:

0-cathode gas discharge port, 1-feeding port, 2-raw water inlet pipe, 6-filter, 7-slag discharge port, 11-cathode gas-liquid separation tank, 12-neutralization sedimentation tank, 14-electrochemical reactor, 15-cathode chamber; 16-a material supplementing port; 17-a water storage tank; 18-cathode water inlet pump; 19-a chlorine absorption pipe; 20-anode tail gas separation tank; 21-a direct current power supply; 22-an anode chamber; 23-anode tail gas discharge pipe; a 24-chlorine-oxygen mixture conveying pipe; 25-anode gas-liquid separation tank; 26-a water outlet pipe; 28-chlorine absorption tank; 30-an anode circulation tank; 31-a cathode recycle tank; 34-a cathode circulation pump; 38-anode recycle tank; 40-a cathode tab; 41-anode tab; 42-cathode water outlet pipe; 43-cathode chamber wall; 44-a cathode; 45-cation exchange membranes; 46-cathode water inlet pipe; 47-anode outlet pipe; 48-anode chamber wall; 49-anode; 50-anode water inlet pipe; 51-cathode chamber outlet; 52-anode chamber outlet; 53-cathode chamber inlet; 54-anode chamber inlet; 55-salt supplementing pipe; 61-starting the overflow pipe a; 65. 66-starting the drain pipe; 68. 69-starting the drain pipe; 76-anode starting water inlet pipe; 77-anode starting a water inlet pump; 79-starting the overflow pipe b; 3-5, 8-10, 13, 27, 29, 32-33, 35-37, 39, 56-60, 62-64, 67, 70-75, 78, 80-81-valves.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

The following examples 1-2 describe the high salt and high nitrate industrial wastewater treatment system of the present invention in detail.

Example 1

The present embodiment provides a constant flow continuous flow system, the structure of which is shown in fig. 4, and which mainly includes a neutralization and precipitation tank 12, a filter 6, a water storage tank 17, a cathode water intake pump 18, an electrochemical reactor 14, a dc power supply 21, a cathode gas-liquid separation tank 11, a chlorine gas absorption pipe 19, an anode tail gas separation tank 20, an anode gas-liquid separation tank 25, an anode start water intake pump 77, and related pipelines, valves, and feeding ports. The neutralization and precipitation tank 12, the filter 6 and the water storage tank 17 are two, one neutralization and precipitation tank and one filter form two sets of neutralization and desalination systems, the two water storage tanks are shared by the two sets of systems, the two sets of neutralization and desalination systems are used simultaneously or alternately, the two water storage tanks discharge water alternately to ensure constant-flow water discharge, and only one set of neutralization and desalination system and one water storage tank are provided in fig. 4.

The cathode gas-liquid separation tank 11 is a high-level tank, the top of the high-level tank is provided with a cathode gas discharge port 0 and a water sample inlet, and the water sample inlet is connected with the outlet of the cathode chamber; the bottom of the water sample tank is provided with a water sample outlet which is connected with a tee joint and respectively communicated with the neutralizing and precipitating tank 12 and the inlet of the chlorine absorption pipe 19; the upper part of the tank body is provided with a starting overflow pipe b 77. The anode tail gas separation tank 20 is a middle-position tank, the top of the anode tail gas separation tank is provided with a water sample inlet, a salt supplementing pipe 55 and an anode tail gas discharge port 23, the water sample inlet is connected with the outlet of the chlorine absorption pipe 19, and the salt supplementing pipe 55 is inserted into a water sample in the tank; the bottom of the anode chamber is provided with a water sample outlet which is connected with the anode chamber inlet; the upper part of the tank body is provided with a starting overflow pipe a 61. The top of the neutralization sedimentation tank (pool) 12 is provided with a raw water inlet, a feed supplement port 1 and a reuse water inlet; the bottom of the filter is provided with a slag water outlet which is connected with the inlet of the filter; the middle lower part is provided with a supernatant outlet which is connected with a water storage tank 17. The filter 6 is provided with a slag outlet 7, a slag water inlet and a water outlet, and the water outlet is communicated with a water storage tank (pool) 17. The top of the water storage tank (tank) 17 can receive raw water injection, filter effluent injection, neutralization sedimentation tank (tank) 12 effluent injection and sodium hydroxide supplement, and the sodium hydroxide supplement is carried out through a supplement port 16; the bottom is provided with a water sample outlet which is communicated with the inlet of the cathode water inlet pump 18. The cathode water inlet pump can receive raw water to be directly output (A type raw water) or can receive water storage tank output (B, C two types of water samples), and an outlet of the cathode water inlet pump 18 is communicated with an inlet of the cathode chamber 15. The cathode chamber 15 of the electrochemical reactor is respectively connected with the outlet of the cathode water inlet pump 18 and the inlet of the cathode gas-liquid separation tank 11 at the upstream and downstream, and the inlet and the outlet of the cathode chamber are respectively provided with a spare water outlet 68 and a spare water outlet 65. The anode chamber 22 is connected with the anode tail gas separation tank 20 and the anode gas-liquid separation tank at the upstream and downstream, a spare water outlet 69 and 66 is respectively arranged at the inlet and the outlet of the anode chamber, and the inlet of the anode chamber can also receive a water sample from an anode starting water inlet pump 77. The top of the anode gas-liquid separation tank 25 is provided with a water sample inlet and a gas outlet which are respectively communicated with the anode chamber outlet and the chlorine absorption pipe 19; the bottom is provided with a water sample outlet connected with a water drainage pipe 26. The upstream and downstream of the chlorine absorption pipe 19 are respectively connected with a water sample outlet of the cathode gas-liquid separation tank and a water sample inlet of the anode tail gas separation tank, and a gas inlet is arranged near the inlet and is connected with a gas outlet of the anode gas-liquid separation tank 25. The liquid level when starting the overflow pipe to begin to go out water is the stable liquid level in the cathode gas-liquid separation tank and the anode tail gas separation tank in the stable stage, and the start overflow pipe to begin to go out water and indicate that the water flow with stable flow can be provided for the low reaches.

The raw water of the A type does not need to be pretreated, the neutralization and sedimentation tank 12, the filter 7 and the water storage tank 17 are not used, and the raw water is directly conveyed to the downstream by the cathode water inlet pump 18. For the two types of raw water B, the neutralization and precipitation tank 12 and the filter 7 are not used in the pretreatment, the water storage tank 17 is used as a pretreatment place, the required acid or alkali is supplemented from the supplementing opening 16, and the effluent after the pretreatment is conveyed to the downstream through the cathode water inlet pump. For the pretreatment of four types of raw water C, before the recycled effluent water after the first electric reduction in the starting stage reaches the neutralization and desalination tank, the two sets of neutralization and desalination systems work simultaneously or alternately, and the neutralization and desalination tank of at least one set of neutralization and desalination system is emptied to reach the state of receiving the recycled water; when the recycled effluent after the first electric reduction reaches the neutralization and desalination tank, the two sets of neutralization and desalination systems work alternately, and the two water storage tanks discharge water alternately.

A, B for the two types of three water samples, when the cathode chamber is filled with the cathode pretreatment effluent and the anode chamber is filled with the anode preparation alkaline brine, the cathode water inlet pump 18 and the anode water inlet pump 17 are started simultaneously, and the electrolysis is started simultaneously, but the water supply to the downstream of the cathode chamber and the anode chamber is started after the electrolysis is started for at least tau hours, and the previous cathode chamber and anode chamber effluent is directly discharged through the starting water discharge pipes 65 and 66. The water is discharged through the water outlet pipe 26 only when the water discharged from the anode chamber enters the anode gas-liquid separation tank and the liquid level reaches a designated position. When the water discharged from the cathode chamber enters the cathode gas-liquid separation tank and the overflow pipe b is started to discharge water, the water discharged from the overflow pipe b is cut off and started, and the water is continuously supplied to the downstream. When water flow reaches the inlet of the chlorine absorption pipe 19, chlorine absorption treatment is started, after the effluent of the chlorine absorption pipe 19 enters the anode tail gas separation tank 20, salt supplement is started when salt supplement is needed, the water flow with or without salt supplement is conveyed downstream continuously until the overflow pipe a is started to start effluent (before the overflow pipe a is started to start effluent, the water flow is continuously supplied downstream until the inlet of the anode chamber is reached, but water is not supplied to the anode chamber yet), the effluent of the overflow pipe a is cut off, the anode is closed, a water inlet pump 77 is started, the raw water derivative water flow is used for replacing prepared alkaline brine for feeding, and then the treatment system enters a stabilization stage.

For the four water samples of the C type, the operation from the first electrolysis start to the start of the cathode gas-liquid separation tank before the start of the downstream water supply is the same as the operation of the first two water samples; the operation of conveying water samples to the downstream is the same as the first two types after the cathode gas-liquid separation tank starts to supply water to the downstream until the overflow pipe a is started to discharge water, but the start overflow pipe a and the anode start water inlet pump are not closed when the overflow pipe a is started to discharge water, and the original water derivative is not used for preparing the alkaline brine for the moment. When the recycled water of the cathode electroreduction effluent is conveyed to the upstream and reaches the neutralization and sedimentation tank 12, the pretreatment operation executes the treatment program, the feeding mode, the feeding intensity and the treatment water quantity in the stable stage, and when the new pretreated effluent can provide stable treated water sample output for the downstream, the new pretreated effluent replaces the original treated effluent and is conveyed to the cathode chamber. When new pretreatment water flow reaches the inlet of the cathode chamber, the starting overflow pipe a and the anode start water inlet pump are closed, raw water derivatives are used for replacing prepared alkaline saline water to supply water to the anode chamber, the electrolysis load is adjusted from the treatment water amount per hour based on (1+ r) Q liters to the treatment water amount per hour based on Q liters, and the cathode chamber and the anode chamber stop downstream water supply while the electrolysis load is switched. After the electrolysis load is switched for at least tau hours, water supply to the downstream of the cathode and anode chambers is started, and the effluent of the cathode and anode chambers before the start is directly discharged through the starting drainage pipes 65 and 66. After the supply of water to the downstream is restored, the treatment system enters a stabilization phase. The electrolysis load switching can also be executed after the water sample is switched for tau hours, the effluent of the cathode and anode chambers before the electrolysis load switching can still be conveyed to the downstream, but the water sample conveying to the downstream is stopped after the electrolysis load switching until the downstream conveying is recovered after the switching for at least tau hours. The cathode and anode effluent during the period of stopping downstream water delivery is discharged directly through the start-up drains 65, 66.

The electrochemical reactor 14 according to this embodiment is a two-chamber electrochemical reactor, and the electrochemical reactor may be composed of one basic unit, or may be composed of a plurality of basic units connected in series or in parallel. As shown in fig. 1, the basic unit of the electrochemical reactor comprises an anode chamber wall 48, an anode 49, a cation exchange membrane 45, a cathode 44 and a cathode chamber wall 43. The anode is a titanium substrate dimensionally stable tensile electrode, and the surface of the electrode is provided with a precious metal sintered coating for anode electrochemical oxygen evolution and chlorine evolution. The cathode is a metal mesh electrode or a plate electrode. In the reactor composed of a plurality of basic units, the cathode chamber wall and the anode chamber wall can be integrated in the reactor, and the cathode chamber wall and the anode chamber wall in the reactor can be plastic or metal. A gap is arranged between the anode chamber wall of the basic unit and the cation exchange membrane to form an anode chamber 22, and the anode is inserted into the anode chamber; a gap is arranged between the cation exchange membrane and the wall of the cathode chamber to form a cathode chamber 15, and the cathode is inserted into the cathode chamber; in a reactor consisting of one basic unit, the anode and the cathode are partially protruded outside the chamber to form an anode tab 41 and a cathode tab 40, and in a reactor consisting of a plurality of basic units, if the inner cathode and anode chamber walls and the anode chamber wall are all made of metal, the inner cathode and anode may have no tab. Cathode chambers of all units of the reactor are communicated with each other to form a cathode chamber of the reactor, and the cathode chamber has only one inlet 53 and one outlet 51 to the outside in function and is respectively connected with an external cathode water inlet pipe 46 and a water outlet pipe 42; the anode chambers of the respective units are interconnected to form the anode chamber of the reactor, and functionally the anode chambers have only one inlet 54 and one outlet 52 to the outside, respectively, and are connected to the external anode inlet pipe 50 and the anode outlet pipe 47, respectively. Different units of the reactor are electrically connected in parallel or in series, and functionally, the cathode and the anode are respectively connected with a low potential terminal and a high potential terminal of the direct current 21 by only one lead.

Example 2

The present embodiment provides an isometric batch processing system, as shown in fig. 3, which mainly includes a pretreatment system, an electrochemical treatment system, a chlorine absorption system, and related valves, pipelines, and feeding devices, wherein the pretreatment system can be selected according to water quality conditions or other considerations, and can be implemented by controlling the valves when the pretreatment system is retained and not needed. The pretreatment system mainly comprises a neutralization and sedimentation tank 12, a filter 6 and a water storage tank 17. The electrochemical treatment system mainly comprises a direct current power supply 21, an electrochemical reactor 14, a cathode circulation tank 31, a cathode circulation pump 34, an anode circulation pump 38 and an anode circulation tank 30. The chlorine absorption system is primarily a chlorine absorption tank 28. The material supplementing device comprises two pretreatment material supplementing ports 1 and 16 and an anode salt supplementing port 55.

The cathode circulation tank 31, the cathode chamber 15 and related circulation pipelines form a storage space for processing the water sample by electroreduction, the cathode circulation tank has the functions of feeding, gas-liquid separation and exhaust (the feeding function can be moved to the water storage tank), and in the processing process, the electroreduction water sample is driven by the cathode circulation pump 34 to circularly flow between the cathode circulation tank 31 and the cathode chamber 15. The anode circulating tank 30, the anode chamber 22 and the related circulating pipelines form a storage space for treating the water sample by electrooxidation, the anode circulating tank 30 has the functions of salt supplement, gas-liquid separation and exhaust, and can receive the water sample flowing from the chlorine absorption tank, and the electrooxidation water sample is driven by the anode circulating pump 38 to circularly flow between the anode circulating tank 30 and the anode chamber 22 in the treatment process. The chlorine absorption tank 28 is a high-level tank, has both separation and exhaust functions, and can receive the flow of the electrically reduced effluent and simultaneously flow a water sample to the anode circulation tank. The pretreatment system can be operated continuously or intermittently as long as the batch water amount can be ensured. For a water sample needing precipitation and desalination treatment, neutralizing and precipitating raw water in a neutralization and precipitation tank, placing the neutralized and precipitated raw water to form supernatant, discharging the supernatant into a water storage tank, discharging a formed slag water layer into a filter, and discharging water separated from the filter into the water storage tank; the pretreatment needs material supplement, and the material supplement is carried out from a material supplement port 1 on the neutralization sedimentation tank and a material supplement port 16 on the water storage tank; the water sample to be reused is pumped into the neutralization and sedimentation tank by opening the valve 37 and the cathode circulating pump 34 and matching with the opening and closing of other related valves when the electric reduction water is needed for the pretreatment. For water samples without desalting sediment, pretreatment and feeding can be completed through a feeding port 16 on a cathode circulating tank, but can also be completed through a feeding port 16 on a water storage tank 17.

In an operation period of a stable stage, four batches of water samples are respectively in four processing states of pretreatment, electroreduction, chlorine absorption, electrooxidation and the like, and a water storage tank is kept in an empty tank state in the water sample processing process. The effluent after pretreatment is stored in a water storage tank, when the treatment period is finished, the electrooxidation water sample is discharged from an anode circulating tank, then the water sample in a chlorine absorption tank is completely transferred to the anode circulating tank, then the electroreduction water sample is transferred to the chlorine absorption tank and a neutralization precipitation tank in a share mode according to the recycling ratio, then the water sample in the water storage tank is completely transferred to a cathode circulating tank, and after the operation is finished, the electrowinning is started to perform electrowinning to enter a new batch treatment period.

In the starting stage, the first batch of water sample is directly transferred to the cathode circulating tank after the pretreatment is finished, electrolysis is started after the prepared anodic electrooxidation water sample is injected into the anode circulating tank (or the initial anodic water sample can be directly prepared in the anode circulating tank), the pretreatment of the raw water is repeated in the electrolysis process, and the second batch of pretreatment effluent is stored in the water storage tank for standby. After the first electrolysis is finished, the first batch of electro-reduction effluent is transferred to a chlorine absorption tank and a neutralization precipitation tank (C type) in a share mode, the second batch of pretreatment effluent in a water storage tank is transferred to a cathode circulating pump in the cathode circulating pump, the anode water sample is changed into a new batch of preparation water sample, the prepared water sample is the same as the first batch of preparation water sample, and then the electrolysis is started. And (3) conveying gas released by the anode water sample in the second electrolysis process to a chlorine absorption tank to be absorbed by alkaline water, adding a third water sample in a neutralization precipitation tank while carrying out electrolysis, wherein the volume of the third water sample is equal to the stable batch treatment amount, then carrying out third pretreatment, carrying out the treatment procedure and the material supplement intensity of the stable stage of the third pretreatment, and discharging the water sample after the third pretreatment into a water storage tank for later use. And (3) entering a stable treatment stage when the third electrolysis is started, finishing the circulation of the water sample according to the circulation sequence of the stable stage after the electrolysis is finished, and starting a new treatment period. The water samples (A type and B type) which do not need to be neutralized and precipitated can be directly added into the cathode circulating tank (or the treated water sample is firstly discharged into the water storage tank for pretreatment of alkalinity adjustment and then flows to the cathode circulating tank) according to the treatment volume of the stabilization treatment stage in the starting stage, and the prepared alkaline saline water is added into the anode circulating tank, and then electrolysis is started. After the first electrolysis is finished, discharging the electro-reduction effluent into a chlorine absorption tank, adding a second batch of pretreatment effluent into a cathode circulating tank, replacing a water sample in an anode circulating tank with a new batch of prepared alkaline saline water, starting the second electrolysis after the operation is finished, entering a stable operation stage, and then executing circulation and other operations of the stable operation stage.

The electrochemical reactor 14 described in this example is also a two-chamber type electrochemical reactor, and the structure of the basic unit is the same as that of the electrochemical reactor in example 1, as described in detail in example 1.

The following examples 3-6 describe the method for treating high-salinity and high-nitrate industrial wastewater in detail, the treatment method of the present invention can treat 3 water samples with zero desalting load, as shown in table 1, and can treat 4 water samples with non-zero desalting load, as shown in table 2, and the total of 3+4 is 7. The invention can provide 1+ 7-8 anode water sample dosing schemes in the starting stage, as shown in tables 2-4. The invention can provide 2 operation schemes of equal-volume batch treatment and constant-flow continuous flow. Therefore, the present invention has 7 × 8 × 2 ═ 112 working examples. For simplicity, the present invention combines the more common embodiments of the operations into one group, which is four groups, and the following embodiments 3-6 each represent one group.

Example 3

The embodiment provides a high-salinity high-nitrate industrial wastewater treatment method, wherein a raw water sample is one of a class A and a class B, and the operation scheme is as follows: constant flow continuous flow (system described in fig. 4), start-up phase anode water sample dosing protocol: all 8 kinds.

The treatment method is implemented by using the constant flow continuous flow system (fig. 4) described in example 1, specifically:

in the pretreatment, for the group a raw water, the valves 3, 59, 10 and 8 are closed, and the valves 4 and 9 are opened; for group B raw water, valves 3, 59 and 9 are closed and valves 4, 8 and 10 are opened.

In the starting stage, the raw water is pretreated by two types of three water samples according to respective initial feeding parameters in table 2, acid or alkali is supplemented through the feeding port 16, then the pretreated effluent is filled in the cathode chamber 15 and the previous pipeline, the valves 63 and 71 are opened during the water filling operation, and the valves 62 and 70 are closed. According to the anode batching intensity shown in the table 2-4, an anode water sample is prepared by using low-hardness water such as deionized water or purified water and the like as a treated water sample, then the anode chamber 22 is filled, an anode starting water inlet pipe 76 is filled, valves 64, 74 and 75 are closed during water filling operation, and valves 67, 72 and 73 are opened.

After the preparation work is finished, after the two water filling operations are finished, the cathode water inlet pump 18 and the anode starting water inlet pump are used for driving a cathode water sample and an anode water sample to flow respectively according to the flow rate of Q liters per hour, the direct-current power supply is started for electrolysis when the flow starts, and the pretreatment speed after the start meets the requirement of water flow rate. The amounts of water flowing through the cathode and anode during electrolysis are discharged from the cathode and anode start-up drains 65, 66, respectively, and after at least τ hours from the start of electrolysis the valves 62, 64 are opened and the valves 63, 67 are closed, and before that the valves 59, 80, 27 have been closed and the valve 78 has been opened. The operation is continued until the water level in the cathode gas-liquid separation tank reaches the level of the start overflow pipe b79, the start overflow pipe b starts to discharge water, then the valves 78 and 75 are closed, and the valves 80, 58 and 60 are opened, before the water level in the anode gas-liquid separation tank reaches the steady-stage water level, and the valve 27 is opened. When the cathode electroreduction effluent water flow reaches the chlorine absorption tank, the valve 57 is opened, when the water flow reaches the tail gas separation tank 20, the valve 58 is opened for the condition that salt is required to be stably supplemented, and the salt supplementing strength of the anode is the salt supplementing strength required by various treated water samples according to the table 4. When the overflow pipe a61 is started to start water outlet, the valves 60 and 73 are closed, the valve 75 is opened, the valve 73 is closed, the anode starts the water inlet pump 77, then the anode is stopped from supplying water for preparing water samples, the anode chamber water inlet is connected with the raw water derived water samples, and the system enters a stabilization stage.

The stable stage of the high-salt and high-nitrate industrial wastewater treatment method comprises the following steps (see figure 2): (1) a pretreatment step of desalting or adjusting alkalinity: removing metal ions which can form hydroxide precipitates in the wastewater, and adjusting the alkalinity; (2) and (3) carrying out electro-reduction for removing nitrate nitrogen: nitrate radical in the waste water is subjected to electro-reduction reaction in an electrochemical reactor to generate N₂And NH₄ ⁺And simultaneously also by-product H₂And OH^-(ii) a (3) Chlorine gas absorption and ammonia nitrogen removal: using OH generated in step (2)^-Absorb chlorine and react on NH₄ ⁺Chemical oxidation is carried out to generate N₂And Cl^-(ii) a The chemical reaction equation is as follows: (4) electrooxidation to evolve oxygen and chlorine: utilizing Cl generated in step (3)^-And OH produced in step (2)^-And (4) carrying out electro-oxidation reaction to generate chlorine and oxygen, and returning the chlorine to the step (3) for absorption.

In the stable stage, the water surfaces in the cathode gas-liquid separation tank, the anode tail gas separation tank and the anode gas-liquid separation tank are kept stable, and the pretreated water sample passes through the cathode chamber, the cathode gas-liquid separation tank, the chlorine absorption pipe, the anode tail gas separation tank, the anode chamber and the anode gas-liquid separation tank in sequence at a constant flow rate under the driving of the cathode water inlet pump, and is discharged from the anode gas-liquid separation tank. During the operation, the materials are supplemented according to the feeding parameters in the tables 2-4, and the hypochlorous intensity in the effluent is shown in the tables 2-4.

Example 4

The embodiment provides a high-salinity high-nitrate industrial wastewater treatment method, the raw water sample is four types C, and the operation scheme is as follows: constant flow continuous flow (system described in fig. 4), start-up phase anode water sample dosing protocol: all 8 kinds.

The treatment method is implemented by using the constant flow continuous flow system described in embodiment 1, and specifically comprises the following steps:

the device is used for treating C-type raw water, valves 4, 8 and 9 are closed, a valve 10 is opened, valves 3, 5 and 13 are opened or closed according to the change along with time, and two sets of pretreatment devices are alternately used (only one is shown in the figure) so as to ensure that stable treatment flow can be provided for downstream treatment.

In the starting stage, raw water of various water samples is pretreated according to initial feeding parameters in the table 3, precipitation treatment and alkali feeding are completed through a feeding port 1, acid feeding is completed through a feeding port 16 after precipitation, and the pretreatment in the preparation stage does not execute cathode electroreduction effluent recycling. The pretreated effluent is filled in the cathode chamber 15 and the previous pipeline, and the valves 63 and 71 are opened and the valves 62 and 70 are closed during the cathode water filling operation. The anode water sample is prepared by using low-hardness water such as deionized water or purified water according to the anode ingredient strength shown in tables 2 to 4, then the anode chamber 22 and the anode starting water inlet pipe 76 are filled, the valves 64, 74 and 75 are closed, and the valves 67, 72 and 73 are opened during the anode water filling operation.

After the preparation work is finished, the cathode and anode water samples are driven to flow according to the flow of (1+ r) Q liters per hour and the flow of Q liters per hour respectively, the recycling proportion parameter values are shown in a table 3, the cathode and anode water samples are driven by a cathode water inlet pump 18 and an anode starting water inlet pump 77 respectively, a direct-current power supply is started to electrolyze at the same time of the beginning of the flow, a pretreatment system can provide cathode pretreatment effluent according to the required flow in the electrolysis process, anode water distribution can be conveyed according to the required flow, and the electrolysis treatment load is (1+ r) Q liters per hour. The amounts of cathode and anode water flowing through the electrolysis are discharged from cathode and anode start-up drains 65 and 66, respectively, and after at least τ/(1+ r) hours from the start of electrolysis, valves 62 and 64 are opened and valves 63 and 67 are closed, and valves 59, 80 and 27 have been closed and valve 78 has been opened. The operation is continued until the water level in the cathode gas-liquid separation tank 11 reaches the level of the start overflow pipe b79, the start overflow pipe b79 starts to discharge water, then the valves 78, 75 are closed, the valves 80, 58, 59, 60 are opened, before these operations, the neutralization settling tank 12 and the filter 6 of one set in the pretreatment device are emptied, the valves 3, 5, 13 thereof are closed, the reuse water reaches the neutralization settling tank 12 of the other set, the pretreatment is replaced by the same, the valve 3 thereof is opened, and the valves 5, 13 are closed or opened as required. After the valve 80 is opened, when the water flow conveyed downstream through the valve 80 reaches the chlorine absorption pipe 19, the valve 57 is opened (the previous chlorine generated by the anode is directly discharged through the valve 81, the valve 81 is closed when the chlorine absorption is started), when the water flow reaches the anode tail gas separation tank 20, if the salt supplementing amount in the stabilization stage is not equal, the salt supplementing strength of the anode shown in the table 4 is started to supplement salt for the treated water sample at a constant speed through the salt supplementing pipe 55, the water flow is continuously conveyed after the salt supplementing or the salt supplementing is not performed, then when the water surface in the anode tail gas separation tank reaches the plane of the starting overflow pipe a61, the overflow pipe a61 is started to start the constant-flow water outlet, and then the water outlet is continued to wait for the completion of the pretreatment and other related operations. The flow rate of water supplied to the downstream of the valve 80 is kept at Q liters per hour, meanwhile, water is continuously supplied to the downstream of the valve 59, the flow rate is kept at rQ liters per hour, after the return water flow reaches the pretreatment system, the flow rate of the pretreated raw water is reduced from the previous (1+ r) Q liters per hour to Q liters per hour, the return water starts to participate in the pretreatment, the material replenishing strength required by the pretreatment is changed from the initial replenishing strength to the stable replenishing strength, the replenishing parameters of various treated water samples are shown in a table 2, the water which needs to be replenished with alkali still needs to be replenished from a replenishing port 1, and the discharged water after precipitation and filtration needs to be replenished with acid from a replenishing port 16. After the reuse water is pretreated for a while, if the water outlet speed reaches a stable and continuous flow rate of (1+ r) Q liters per hour, the water flow is used to replace the water flow which is not pretreated before and is supplied from the valve 10 to the downstream, and the new water flow flows to the cathode chamber along with the old water flow. Once the new water flow reaches the inlet of the cathode chamber, the valves 73 and 70 are closed, the anode starts the water inlet pump 77, the valve 72 is opened, the anode water sample in the waiting state before is used for replacing the prepared alkaline saline water to convey water to the anode chamber, and the flow rate is still Q liters per hour. After the anode water flow is switched for tau/(1 + r) hours, when the new water flows of the cathode and the anode reach the outlet of the cathode chamber or the anode chamber, the valves 62 and 64 are immediately closed, the valves 63 and 67 are opened, the water supply to the downstream of the cathode chamber and the anode chamber is temporarily stopped, and the water outlet of the cathode chamber and the anode chamber is respectively discharged from the water outlet pipes 65 and 66. While these valve switching operations are being performed, the output current of the dc power supply 21 is reduced from the original processing load based on (1+ r) Q liters per hour to the processing load based on Q liters per hour, and after the current is adjusted for at least τ/(1+ r) hours, the valves 62 and 64 are opened, the valves 63 and 67 are closed, the supply of water to the downstream of the cathode and anode chambers is resumed, and the system enters the stabilization stage.

Example 5

The embodiment provides a high-salinity high-nitrate industrial wastewater treatment method, wherein a raw water sample is one of a class A and a class B, and the operation scheme is as follows: isometric batch processing (system described in fig. 3), start-up phase anode water sample dosing protocol: all 8 kinds.

The method for implementing the treatment by adopting the isometric batch treatment system in the embodiment 2 comprises the following specific steps:

when the system is used for the A-type raw water, the valves 3, 8, 10 and 37 related to the pretreatment are closed, and the valve 4 is opened or closed as required; for the type B raw water, the valves 3, 4, 37 relating to the pretreatment are closed, and the valves 4, 8, and 10 are opened or closed as necessary. For the A-type raw water, no pretreatment is needed before any raw water enters the cathodic electroreduction treatment. For two water samples of type B, when the raw water is pretreated, the valve 10 is closed, the valve 8 is opened, the raw water with the volume of Q liters is injected into the water storage tank 17, and then the raw water is supplemented according to the strength of acid supplement or alkali supplement to adjust the alkalinity of the water samples, and the pretreatment of each batch of raw water is carried out. For two water samples of class B, the initial acid-supplementing strength or the initial alkali-supplementing strength of each water sample is the same as the stable acid-supplementing strength or the stable alkali-supplementing strength. After the first batch of cathode electroreduction water sample Q is prepared completely, the valves 33 and 35 are opened, the valves 32 and 36 are closed, and raw water with each batch of volume is pumped into a cathode circulation pipeline from the valve 33 through a cathode circulation pump 34. The volume of the first batch of anodic electrooxidation water samples is Q liters, and deionized water or purified water or other low-hardness pure water samples are prepared according to the anodic alkali-complex strength and the anodic salt-complex strength (shown in tables 2 and 4) of various raw water treatments. After the anode water sample is prepared, an anode circulating pump is used for pumping the water from an anode starting water inlet pipe 76 into an anode circulating pipeline, valves 27, 39 and 74 are closed during injection, and valves 73 and 39 are opened after the injection is finished.

After the first batch of cathode and anode water samples are completely injected, the direct current power supply 31 is started to carry out electrolysis, the electrolysis current and the electrolysis time meet the requirement of electric quantity intensity, and the cathode and anode water samples circularly flow in respective circulating pipelines under the driving of respective circulating pumps in the electrolysis process. The gas generated by the cathode and anode reactions in the first electrolysis process is exhausted, and the gas generated by the cathode electroreduction reaction in each later electrolysis process is treated in the same way. While the first electrolysis is carried out, the same method for preparing the cathode and anode water samples for the first electrolysis is repeated once, and the cathode and anode water samples are prepared for the second electrolysis. After the first electrolysis is finished, opening the valve 27 to directly drain the anode water sample, and then injecting a second batch of prepared electrooxidation water sample into the anode circulating pipeline according to the same operation as the first electrolysis; closing the valve 35, opening the valve 36, pumping the first batch of electrically reduced water sample into the chlorine absorption tank 28 by using the cathode circulating pump 31, closing the valve 29 before pumping, and then performing the same treatment on the circulation of each batch of electrically reduced effluent from the cathode circulating pipeline to the chlorine absorption tank, and injecting Q liters of second batch of pre-treated effluent into the cathode circulating pipeline according to the first cathode water sample injection operation after the circulation is finished. When the water samples of the cathode and the anode for the second electrolysis are injected into the respective circulation pipelines, the second electrolysis is started, and the operation and control of the first electrolysis and each subsequent electrolysis are the same as those of the first electrolysis. The chlorine-oxygen mixed gas generated by the anode reaction in the second electrolysis process is conveyed to a water sample in a chlorine absorption tank through a pipeline 24, the chlorine in the chlorine-oxygen mixed gas is absorbed by alkaline water, the residual oxygen and the newly generated nitrogen are discharged, the chlorine-oxygen mixed gas generated in the subsequent electro-oxidation process of each batch of water samples is processed in the same way, and the tail gas and the newly generated nitrogen after the chlorine absorption are processed in the same way. A third sample of the cathodically electroreduced water was also prepared during the second electrolysis run.

After the second electrolysis, the valve 27 is opened to directly discharge the anode water sample, the valve 27 is closed after the discharge, the valve 29 is opened, the effluent water after chlorine absorption is discharged into the anode circulating tank 30, then the electroreduction effluent water after the second electrolysis flows into the chlorine absorption tank from the cathode circulating pipeline, the pre-treatment effluent water which is approved and prepared in the third batch flows into the cathode circulating pipeline, after the flow, the cathode water sample and the anode water sample all become raw water derivatives, and the treatment process starts to enter a stable stage. In the stabilization phase, if the anodic electrooxidation water samples need salt supplementation, the various water samples are supplemented with salt before electrolysis according to the anodic stable salt supplementation strength shown in table 3, the salt supplementation is carried out through the salt supplementation pipe 55, the valve 58 is opened and closed before and after the salt supplementation, and then the electrolysis and other operations are started. In the stabilization phase, for two water samples of class B, four water samples are in different processing states: pretreatment, electroreduction, chlorine absorption and electrooxidation, wherein for a class A water sample, three water samples are in different treatment states: electroreduction, chlorine absorption and electrooxidation.

Example 6

The embodiment provides a high-salinity high-nitrate industrial wastewater treatment method, the raw water sample is four types C, and the operation scheme is as follows: isometric batch processing (system described in fig. 3), start-up phase anode water sample dosing protocol: all 8 kinds.

The method for implementing the treatment by adopting the isometric batch treatment system in the embodiment 2 comprises the following specific steps:

before the treatment, the valves 8, 4, 10, 5 and 13 are closed, the valve 3 is opened, Q liters of raw water (1+ r) is injected into the neutralization settling tank, then alkali is supplemented according to the initial alkali supplementing strength shown in the table 3 through the material supplementing port 1, the valve 13 is opened after the precipitation treatment is placed for a period of time, and the upper layer of clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization and sedimentation tank is discharged into the filter for filtering, the effluent water formed in the filtering process is discharged into the water storage tank 17, and the solid slag formed after filtering is discharged through the slag outlet 7. And when the acid is required to be supplemented to the treated water sample, supplementing acid according to the initial acid supplementing strength shown in the table 3, so that the pretreatment of the first raw water is finished, the effluent is temporarily stored in the water storage tank 17, and the preparation of the first electro-reduction water sample is finished. Preparing a first electroreduction water sample and preparing a first electrooxidation water sample simultaneously: the volume of the first batch of anodic electrooxidation water samples is Q liters, and deionized water or purified water or other low-hardness pure water samples are prepared according to the anodic alkali-complex strength and the anodic salt-complex strength (shown in tables 3 and 4) of various raw water.

After the first batch of cathode and anode water samples are prepared, the valves 10, 33 and 35 are opened, the valves 32, 36 and 37 are closed, and then the cathode circulating pump 34 is started to transfer the first batch of cathode water samples to the cathode circulating pipeline; the valve 73 is opened, the valves 74, 39, 27 are closed, and then the anode circulating pump 38 is opened to inject the first batch of the anode sample water into the anode circulating line through the anode starting water inlet pipe 76. After the two water samples are injected, the valves 10 and 33 are closed, the valve 32 is opened, the cathode circulating pump 34 drives the cathode water sample to circularly flow in the cathode circulating pipeline, the valve 73 is closed, the valve 39 is opened, and the anode circulating pump 38 drives the anode water sample to circularly flow in the anode circulating pipeline. After two water samples start to circularly flow in respective pipelines, the direct current power supply 21 is started to start first electrolysis, the electrolysis treatment load is (1+ r) Q liter, and the current, voltage and time depend on the performance of the reactor and the specific properties of the water samples. The cathode and anode gases generated and evolved during the first electrolysis are evacuated through exhaust pipes 0 and 24, respectively. In the first electrolysis process, a second batch of cathode and anode water samples are prepared simultaneously, and the pretreatment process, the treatment water quantity and the treatment formula are the same as those of the first batch of cathode and anode water samples in other aspects. After the first electrolysis is finished, the valve 27 is opened to discharge all the first batch of anode effluent, and then a second batch of water samples are injected into the anode circulation pipeline and driven to flow circularly according to the injection operation and the water sample circulation driving operation of the first batch of anode water samples. And before the first electrolysis is finished, temporarily storing the prepared second batch in the water storage tank 17, emptying the precipitation neutralization tank 12 and the filter 6, closing the valves 3, 5 and 13, closing the valve 35 and opening the valve 37 after the first electrolysis is finished, firstly pumping the Q liter of the first batch of electric reduction effluent into the chlorine absorption tank 28 by using the cathode circulating pump, closing the valve 29 in advance before pumping, then closing the valve 37, opening the valve 36, pumping the residual rQ liter of the first batch of electric reduction effluent into the neutralization precipitation tank 12 by using the cathode circulating pump 15, and then closing the valve 37. And after the cathode circulating tank is emptied, injecting, opening and closing a valve and circularly driving the prepared second batch of cathode water samples according to the same operation on the first batch of cathode water samples. After the second batch of cathode and anode water samples start to circularly flow in respective circulating pipelines, the direct current power supply 21 is started to start the second electrolysis, and the electric quantity intensity, the voltage, the current and the electrolysis time are basically the same as those of the first electrolysis. In the second electrolysis process, the gas nitrogen-hydrogen mixture generated by the cathode reaction is evacuated through the cathode gas discharge port 0, the gas chlorine-oxygen mixture generated by the anode reaction is conveyed into a water sample in the chlorine absorption tank through the pipeline 24, and the residual oxygen after the chlorine is absorbed and the newly generated nitrogen are evacuated through the anode tail gas discharge port 23. A pretreatment of the third batch of water samples was also performed during the second electrolysis run: opening a valve 3 to inject Q liters of raw water into a neutralization settling tank, mixing the raw water with the injected rQ liters of first batch of electro-reduction effluent, and then supplementing alkali according to the stable alkali supplementing strength shown in the table 3 if the alkali is needed to be supplemented; after the neutralization of the sediment is finished and the sediment is placed for a period of time, the valve 13 is opened, and the upper layer clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization settling tank is discharged into the filter for filtering, the solid slag formed after filtering is discharged through the slag outlet 7, and the effluent formed in the filtering process is discharged into the water storage tank 17; finally, if the pretreatment needs acid supplementation, the water sample in the water storage tank 17 is supplemented with acid according to the stable acid supplementation strength shown in the table 3, if the pretreatment does not need, the water sample can be directly used for electroreduction treatment, and after the third batch of cathode electroreduction water samples are prepared, the valves 5 and 13 are closed. The water samples prepared and used for the third cathodic electro-reduction treatment and the subsequent cathodic electro-reduction water samples all count (1+ r) Q liters, but only Q liters in the water samples are not subjected to electro-reduction treatment.

After the second electrolysis, the valve 27 is firstly opened to discharge the water sample after the second anodic electrooxidation treatment out of the treatment system, then the valve 27 is closed, the valve 29 is opened, the water sample after the chlorine absorption treatment is discharged into the anode circulation pipeline, then the valves 29 and 35 are closed, the valve 36 is opened, Q liter of the water sample after the second electroreduction treatment is pumped into the chlorine absorption tank by using the cathode circulation pump, then the valve 36 is closed, the valve 37 is opened, the residual rQ liter of the second electroreduction effluent is transferred into the precipitation neutralization tank 12 by using the cathode circulation pump, and before the second electroreduction effluent is transferred, the cathodes of the valves 2, 5 and 13 are closed in advance. After the cathode circulation tank is emptied, the valves 37 and 32 are closed, the valves 30, 33 and 35 are opened, the prepared third batch of sample water for cathodic reduction is pumped into the cathode circulation tank 31 from the water storage tank 17 by the cathode circulation pump 24, then the valves 10 and 33 are closed, the valve 32 is opened, and then the third batch of sample water is driven to circulate in the cathode circulation pipeline by the cathode circulation pump. After the effluent after the first batch of chlorine gas is absorbed flows to the anode circulating tank, the anode circulating pump 38 is started to drive the anodic electrooxidation water sample to circularly flow in the anode circulating pipeline; if the treated water sample needs salt supplement in the stable stage, the valve 58 is opened, salt supplement is carried out through the salt supplement pipe 55 according to the stable salt supplement strength shown in the table 4, the valve 58 is closed after salt supplement is finished, and salt supplement operation can be carried out before and after the circulating pump is started. And after the cathode and anode water samples start to circularly flow, starting the direct current power supply to perform third electrolytic treatment, and starting the stabilization stage. From the third electrolysis, the treatment load is Q liter, and the current voltage and the electrolysis time are jointly determined by the treatment load, the electric quantity intensity, the treatment requirement, the water sample property and the reactor performance. In the stabilization phase, for four water samples of class C, four water samples are in different processing states: pretreatment, electroreduction, chlorine absorption and electrooxidation, wherein Q liter of electroreduction effluent is recycled in the pretreatment.

The following examples 7-14 give details of the treatment of specific water samples using the high-salinity high-nitrate industrial wastewater treatment method of the present invention.

Example 7

Treating a water sample: the electrolytic nickel-chromium-copper plating wastewater C is prepared from 0.0703M nitrate (nitrate nitrogen 984mg/L), 0.3825M desalting load, 0.2617M chlorinity, 0.04M acidity and 0 alkalinity.

An electrolytic cell: single groove, electrode area 2500cm²。

The treatment method comprises the following steps: equal volume batch treatment.

Processing load: 50L.

Electric quantity intensity: 102kC/L (kilocoulombs per liter).

The specific operation of the treatment of the water sample is as follows:

the processing system is shown in fig. 3. Before the treatment, the valves 8, 4, 10, 5 and 13 were closed, the valve 3 was opened, 57.5L of raw water was poured into the neutralization settling tank, and the initial alkali-replenishing strength C was measured by the replenishing port 1_CJ0.4225M sodium hydroxide is added, after the precipitation treatment, the solution is left for a period of time, the valve 13 is opened, and the upper clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization settling tank is discharged into the filter for filtering, the effluent water formed in the filtering process is discharged into the water storage tank 17, and the solid slag formed after filtering is dischargedAnd discharging the slag hole 7. Adding acid into the water storage tank 17 according to the initial acid-supplementing strength C_CSHydrochloric acid was added at 0.0684M, and thus the pretreatment of the first batch of raw water was completed, the effluent was temporarily stored in the water storage tank 17, and the preparation of the first batch of electroreduction water sample was completed. Preparing a first electroreduction water sample and preparing a first electrooxidation water sample simultaneously: the volume of the first anodic electrooxidation water sample is 50L, and deionized water is used for preparing alkali according to the anode alkali strength C_AJ1.1875M and anodic salt complex strength C_AYSodium hydroxide and sodium chloride were added to 0.3M, respectively, to prepare a solution.

After the first batch of cathode and anode water samples are prepared, the valves 10, 33 and 35 are opened, the valves 32, 36 and 37 are closed, and then the cathode circulating pump 34 is started to transfer the first batch of cathode water samples to the cathode circulating pipeline; the valve 73 is opened, the valves 74, 39, 27 are closed, and then the anode circulating pump 38 is opened to inject the first batch of the anode sample water into the anode circulating line through the anode starting water inlet pipe 76. After the two water samples are injected, the valves 10 and 33 are closed, the valve 32 is opened, the cathode circulating pump 34 drives the cathode water sample to circularly flow in the cathode circulating pipeline, the valve 73 is closed, the valve 39 is opened, and the anode circulating pump 38 drives the anode water sample to circularly flow in the anode circulating pipeline. After two water samples start to circularly flow in respective pipelines, the direct current power supply 21 is started to start first electrolysis, the electrolysis treatment load is 57.5L, the average current is 140A, the average voltage is 3.13V, and the electrolysis time is 11.4 h. The cathode and anode gases generated and evolved during the first electrolysis are evacuated through exhaust pipes 0 and 24, respectively. In the first electrolysis process, a second batch of cathode and anode water samples are prepared simultaneously, and the pretreatment process, the treatment water quantity and the treatment formula are the same as those of the first batch of cathode and anode water samples in other aspects. After the first electrolysis is finished, the valve 27 is opened to discharge all the first batch of anode effluent, and then a second batch of water samples are injected into the anode circulation pipeline and driven to flow circularly according to the injection operation and the water sample circulation driving operation of the first batch of anode water samples. Temporarily storing the second prepared batch in the water storage tank 17 before the first electrolysis, emptying the precipitation neutralization tank 12 and the filter 6, closing the valves 3, 5 and 13, closing the valve 35 and opening the valve 37 after the first electrolysis, and firstly reducing 50L of the first batch of electroreduction effluent into negativeThe electrode circulation pump was driven into the chlorine absorption tank 28, the valve 29 was closed in advance before driving, then the valve 37 was closed, the valve 36 was opened, the remaining 7.5L of the first batch of electrically reduced effluent was driven into the neutralization settling tank 12 with the cathode circulation pump 15, and then the valve 37 was closed. And after the cathode circulating tank is emptied, injecting, opening and closing a valve and circularly driving the prepared second batch of cathode water samples according to the same operation on the first batch of cathode water samples. After the second batch of cathode and anode water samples start to circularly flow in respective circulating pipelines, the direct current power supply 21 is started to start the second electrolysis, and the electric quantity intensity, the voltage, the current and the electrolysis time are basically the same as those of the first electrolysis. In the second electrolysis process, the gas nitrogen-hydrogen mixture generated by the cathode reaction is evacuated through the cathode gas discharge port 0, the gas chlorine-oxygen mixture generated by the anode reaction is conveyed into a water sample in the chlorine absorption tank through the pipeline 24, and the residual oxygen after the chlorine is absorbed and the newly generated nitrogen are evacuated through the anode tail gas discharge port 23. A pretreatment of the third batch of water samples was also performed during the second electrolysis run: opening valve 3 to inject 50L raw water into neutralization precipitation tank, mixing with injected 7.5L first batch of electroreduction effluent, and adding alkali according to stable alkali-supplementing strength C_WJ0.3541M sodium hydroxide; after the neutralization of the sediment is finished and the sediment is placed for a period of time, the valve 13 is opened, and the upper layer clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization settling tank is discharged into the filter for filtering, the solid slag formed after filtering is discharged through the slag outlet 7, the effluent water formed in the filtering process is discharged into the water storage tank 17, and at this point, the valves 5 and 13 are closed after the third batch of cathode electroreduction water samples are prepared. The water samples prepared and used for the third cathodic electro-reduction treatment and the subsequent cathodic electro-reduction water samples all amount to 57.5L, but only 50L of the water samples are not subjected to electro-reduction treatment.

After the second electrolysis, the valve 27 is opened to discharge the water sample after the second anodic electrooxidation treatment out of the treatment system, the valve 27 is closed, the valve 29 is opened, the water sample after the chlorine absorption treatment is discharged into the anode circulation pipeline, then the valves 29 and 35 are closed, the valve 36 is opened, 50L of the water sample after the second electroreduction treatment is pumped into the chlorine absorption tank by using the cathode circulation pump, then the valve 36 is closed, the valve 37 is opened, the residual 7.5L of the second electroreduction effluent is transferred into the precipitation neutralization tank 12 by using the cathode circulation pump, and the cathodes of the valves 2, 5 and 13 are closed in advance before the second electroreduction. After the cathode circulation tank is emptied, the valves 37 and 32 are closed, the valves 30, 33 and 35 are opened, the prepared third batch of sample water for cathodic reduction is pumped into the cathode circulation tank 31 from the water storage tank 17 by the cathode circulation pump 24, then the valves 10 and 33 are closed, the valve 32 is opened, and then the third batch of sample water is driven to circulate in the cathode circulation pipeline by the cathode circulation pump. After the effluent after the first batch of chlorine gas is absorbed flows to the anode circulating tank, the anode circulating pump 38 is started to drive the anodic electrooxidation water sample to circularly flow in the anode circulating pipeline. And after the cathode and anode water samples start to circularly flow, starting the direct current power supply to perform third electrolytic treatment, and starting the stabilization stage. From the third electrolysis, the treatment load was 50L, the average voltage was 3V, the average current was 122A, and the electrolysis time was 11.4 h. In the stabilization phase, a total of four water samples were in different treatment states: pretreatment, electroreduction, chlorine absorption and electrooxidation, wherein 7.5L of electroreduction effluent is recycled in the pretreatment. The final effluent nitre and nitrogen removal rate is 97.4 percent, and the content of the hypochlorous is less than 0.002M.

Control criterion parameters: degree of electromigration C_Na+1.0570M ammonium producing ability C_NH4+0.0130M, maximum residual alkalinity C^* _YJ1.031M, alkali-extracting ability C_SR0.0284M, chlorine yield strength C_Cl0.043M, effective chlorine degree C^* _Cl-0.2617M, highest anodic base strength C^* _AJ1.1915M, 0.004M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.0130M, the alkalinity of the electro-reduction effluent is 1.0830M, the alkalinity of the chlorine absorption effluent is 1.0271M, the nitrate content of the electro-oxidation effluent is 0.0018M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.002M.

Example 8

Treating a water sample: the acid-washing copper-containing wastewater is C-class wastewater, the nitre degree is 0.4746M (the nitre nitrogen is 6645mg/L), the desalting load is 0.6940M, the chlorinity is 0.0324M, the acidity is 0.0060M, and the alkalinity is 0.

An electrolytic cell: single groove, electrode area 2500cm²。

The treatment method comprises the following steps: equal volume batch treatment.

Processing load: 25L.

Electric quantity intensity: 494 kC/L.

The specific operation of the treatment of the water sample is as follows:

the processing system is shown in fig. 3. Before the treatment, the valves 8, 4, 10, 5 and 13 are closed, the valve 3 is opened to inject 28.75L of raw water into the neutralization precipitation tank, then sodium hydroxide is supplemented through the material supplementing port 1 according to the initial alkali supplementing strength of 0.7M, after the precipitation treatment is carried out, the valve 13 is opened after the precipitation treatment is placed for a period of time, and the upper layer of clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization and sedimentation tank is discharged into the filter for filtering, the effluent water formed in the filtering process is discharged into the water storage tank 17, and the solid slag formed after filtering is discharged through the slag outlet 7. And (3) adding hydrochloric acid into the water storage tank 17 according to the initial acid-adding strength of 0.4118M, so that the pretreatment of the first raw water is finished, the effluent is temporarily stored in the water storage tank 17, and the preparation of the first electro-reduction water sample is finished. Preparing a first electroreduction water sample and preparing a first electrooxidation water sample simultaneously: the volume of the first anodic electrooxidation water sample is 25L, and sodium hydroxide and sodium chloride are respectively added into deionized water according to the anode alkali-blending strength of 5.6112M and the anode salt-blending strength of 0.7M for preparation.

After the first batch of cathode and anode water samples are prepared, the valves 10, 33 and 35 are opened, the valves 32, 36 and 37 are closed, and then the cathode circulating pump 34 is started to transfer the first batch of cathode water samples to the cathode circulating pipeline; the valve 73 is opened, the valves 74, 39, 27 are closed, and then the anode circulating pump 38 is opened to inject the first batch of the anode sample water into the anode circulating line through the anode starting water inlet pipe 76. After the two water samples are injected, the valves 10 and 33 are closed, the valve 32 is opened, the cathode circulating pump 34 drives the cathode water sample to circularly flow in the cathode circulating pipeline, the valve 73 is closed, the valve 39 is opened, and the anode circulating pump 38 drives the anode water sample to circularly flow in the anode circulating pipeline. After the two water samples start to circularly flow in respective pipelines, the direct current power supply 21 is started to start first electrolysis, the electrolysis treatment load is 28.75L, the average current is 258.8A, the average voltage is 3.11V, and the electrolysis time is 15.8 h. The cathode and anode gases generated and evolved during the first electrolysis are evacuated through exhaust pipes 0 and 24, respectively. In the first electrolysis process, a second batch of cathode and anode water samples are prepared simultaneously, and the pretreatment process, the treatment water quantity and the treatment formula are the same as those of the first batch of cathode and anode water samples in other aspects. After the first electrolysis is finished, the valve 27 is opened to discharge all the first batch of anode effluent, and then a second batch of water samples are injected into the anode circulation pipeline and driven to flow circularly according to the injection operation and the water sample circulation driving operation of the first batch of anode water samples. And before the first electrolysis is finished, temporarily storing the prepared second batch in the water storage tank 17, emptying the precipitation neutralization tank 12 and the filter 6, closing the valves 3, 5 and 13, closing the valve 35 and opening the valve 37 after the first electrolysis is finished, firstly pumping 50L of the first batch of electro-reduction effluent into the chlorine absorption tank 28 by using the cathode circulating pump, closing the valve 29 in advance before pumping, then closing the valve 37, opening the valve 36, pumping the rest 7.5L of the first batch of electro-reduction effluent into the neutralization precipitation tank 12 by using the cathode circulating pump 15, and then closing the valve 37. And after the cathode circulating tank is emptied, injecting, opening and closing a valve and circularly driving the prepared second batch of cathode water samples according to the same operation on the first batch of cathode water samples. After the second batch of cathode and anode water samples start to circularly flow in respective circulating pipelines, the direct current power supply 21 is started to start the second electrolysis, and the electric quantity intensity, the voltage, the current and the electrolysis time are basically the same as those of the first electrolysis. In the second electrolysis process, the gas nitrogen-hydrogen mixture generated by the cathode reaction is evacuated through the cathode gas discharge port 0, the gas chlorine-oxygen mixture generated by the anode reaction is conveyed into a water sample in the chlorine absorption tank through the pipeline 24, and the residual oxygen after the chlorine is absorbed and the newly generated nitrogen are evacuated through the anode tail gas discharge port 23. A pretreatment of the third batch of water samples was also performed during the second electrolysis run: opening a valve 3 to inject 25L of raw water into a neutralization settling tank, mixing the raw water with the injected 3.75L of first batch of electro-reduction effluent, and then supplementing sodium hydroxide according to the stable alkali supplementing strength of 0.2882M; after the neutralization of the sediment is finished and the sediment is placed for a period of time, the valve 13 is opened, and the upper layer clear water is discharged into the water storage tank 17. After the upper clear water is discharged, the valve 5 is opened, the lower slag water in the neutralization settling tank is discharged into the filter for filtering, the solid slag formed after filtering is discharged through the slag outlet 7, the effluent water formed in the filtering process is discharged into the water storage tank 17, and at this point, the valves 5 and 13 are closed after the third batch of cathode electroreduction water samples are prepared. The water samples prepared and used for the third cathodic electro-reduction treatment and the subsequent cathodic electro-reduction water samples all amounted to 28.75L, but only 25L of the water samples had not been subjected to electro-reduction treatment.

After the second electrolysis, the valve 27 is opened to discharge the water sample after the second anodic electrooxidation treatment out of the treatment system, the valve 27 is closed, the valve 29 is opened, the water sample after the chlorine absorption treatment is discharged into the anode circulation pipeline, then the valves 29 and 35 are closed, the valve 36 is opened, 50L of the water sample after the second electroreduction treatment is pumped into the chlorine absorption tank by using the cathode circulation pump, then the valve 36 is closed, the valve 37 is opened, the residual 7.5L of the second electroreduction effluent is transferred into the precipitation neutralization tank 12 by using the cathode circulation pump, and the cathodes of the valves 2, 5 and 13 are closed in advance before the second electroreduction. After the cathode circulation tank is emptied, the valves 37 and 32 are closed, the valves 30, 33 and 35 are opened, the prepared third batch of sample water for cathodic reduction is pumped into the cathode circulation tank 31 from the water storage tank 17 by the cathode circulation pump 24, then the valves 10 and 33 are closed, the valve 32 is opened, and then the third batch of sample water is driven to circulate in the cathode circulation pipeline by the cathode circulation pump. After the effluent after the first batch of chlorine gas is absorbed flows to the anode circulating tank, the anode circulating pump 38 is started to drive the anodic electrooxidation water sample to circularly flow in the anode circulating pipeline. And after the cathode and anode water samples start to circularly flow, starting the direct current power supply to perform third electrolytic treatment, and starting the stabilization stage. From the third electrolysis, the treatment load was 25L, the average voltage was 3V, the average current was 225A, and the electrolysis time was 15.8 h. In the stabilization phase, a total of four water samples were in different treatment states: pretreatment, electroreduction, chlorine absorption and electrooxidation, wherein 3.75L of electroreduction effluent is recycled in the pretreatment. The final effluent nitre and nitrogen removal rate is 86.8 percent, and the content of the hypochlorous is less than 0.01M.

Control criterion parameters: the degree of electromigration is 5.1162M, the ammonium production capacity is 0.1362M, the highest residual alkalinity is 4.8438M, the alkali production capacity is 0.4058M, the chlorine production strength is 0.4291M, the effective chlorine degree is 0.0324M, the highest anode alkali-blending strength is 5.6316M, and the anode alkali-blending strength deficit is 0.0204M.

Effluent water quality parameters: the nitrate of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.1326M, the alkalinity of the electro-reduction effluent is 5.3886M, the chlorine gas absorption effluent alkalinity is 4.8233M, the nitrate of the electro-oxidation effluent is 0.0629M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.01M.

Example 9

Treating a water sample: the resin exchange wastewater, B type, has the nitre of 0.1442M (the nitre nitrogen is 2019mg/L), the desalting load of 0, the chlorinity of 2.5M, the acidity of 0 and the alkalinity of 0.

An electrolytic cell: single groove, electrode area 2500cm²。

The treatment method comprises the following steps: equal volume batch treatment.

Processing load: 25L.

Electric quantity intensity: 108 kC/L.

The specific operation of the treatment of the water sample is as follows:

the processing system is shown in fig. 3. The valves 3, 4, 37 relating to the pretreatment are closed. When the raw water is pretreated, the valve 10 is closed, the valve 8 is opened, raw water with a volume of 25L is injected into the water storage tank 17, and then hydrochloric acid is supplemented at a supplement acid strength of 0.1416M, so that the pretreatment of each batch of raw water is performed. After the first batch of cathode electroreduction water sample 25L is prepared, the valves 33 and 35 are opened, the valves 32 and 36 are closed, and pretreatment effluent with the volume of 25L is pumped into a cathode circulation pipeline from the valve 33 by the cathode circulation pump 34. The volume of the first batch of anodic electrooxidation water sample is 25 liters, and the first batch of anodic electrooxidation water sample is prepared by adding sodium hydroxide and sodium chloride into purified water according to the anode alkali-blending strength of 0.9428M and the anode salt-blending strength of 0.5M respectively. After the anode water sample is prepared, an anode circulating pump is used for pumping the water from an anode starting water inlet pipe 76 into an anode circulating pipeline, valves 27, 39 and 74 are closed during injection, and valves 73 and 39 are opened after the injection is finished.

And after the first batch of cathode and anode water samples are injected, starting the direct current power supply 31 for electrolysis, wherein the average current is 262.5A, the average voltage is 3.05V, the electrolysis time is 2.9h, and the cathode and anode water samples circularly flow in respective circulating pipelines under the driving of respective circulating pumps in the electrolysis process. The gas generated by the cathode and anode reactions in the first electrolysis process is exhausted, and the gas generated by the cathode electroreduction reaction in each later electrolysis process is treated in the same way. While the first electrolysis is carried out, the same method for preparing the cathode and anode water samples for the first electrolysis is repeated once, and the cathode and anode water samples are prepared for the second electrolysis. After the first electrolysis is finished, opening the valve 27 to directly drain the anode water sample, and then injecting a second batch of prepared electrooxidation water sample into the anode circulating pipeline according to the same operation as the first electrolysis; closing the valve 35, opening the valve 36, pumping the first batch of electrically reduced water sample into the chlorine absorption tank 28 by using the cathode circulating pump 31, closing the valve 29 before pumping, and then performing the same treatment on the circulation of each batch of electrically reduced effluent from the cathode circulating pipeline to the chlorine absorption tank, and injecting Q liters of second batch of pre-treated effluent into the cathode circulating pipeline according to the first cathode water sample injection operation after the circulation is finished. When the water samples of the cathode and the anode for the second electrolysis are injected into the respective circulation pipelines, the second electrolysis is started, and the operation and control of the first electrolysis and each subsequent electrolysis are the same as those of the first electrolysis. The chlorine-oxygen mixed gas generated by the anode reaction in the second electrolysis process is conveyed to a water sample in a chlorine absorption tank through a pipeline 24, the chlorine in the chlorine-oxygen mixed gas is absorbed by alkaline water, the residual oxygen and the newly generated nitrogen are discharged, the chlorine-oxygen mixed gas generated in the subsequent electro-oxidation process of each batch of water samples is processed in the same way, and the tail gas and the newly generated nitrogen after the chlorine absorption are processed in the same way. A third sample of the cathodically electroreduced water was also prepared during the second electrolysis run.

After the second electrolysis, the valve 27 is opened to directly discharge the anode water sample, the valve 27 is closed after the discharge, the valve 29 is opened, the effluent water after chlorine absorption is discharged into the anode circulating tank 30, then the electroreduction effluent water after the second electrolysis flows into the chlorine absorption tank from the cathode circulating pipeline, the pre-treatment effluent water which is approved and prepared in the third batch flows into the cathode circulating pipeline, after the flow, the cathode water sample and the anode water sample all become raw water derivatives, and the treatment process starts to enter a stable stage. In the stable stage, the average voltage of each water sample is electrolyzed and treated with 3V, the average current is 262.5A, and the electrolysis time is 2.9 h. In each treatment cycle of the stabilization phase, a total of four water samples were in different treatment states: pretreatment, electroreduction, chlorine absorption and electrooxidation. The final effluent nitre and nitrogen removal rate is 98.2 percent, and the content of the hypochlorous is less than 0.005M.

Control criterion parameters: the degree of electromigration is 1.1192M, the ammonium production capacity is 0.0560M, the highest residual alkalinity is 0.9512M, the alkali production capacity is 0.1416M, the chlorine production strength is 0.1763M, the effective chlorine degree is 2.6416M, the highest anode alkali-matching strength is 0.9512M, and the anode alkali-matching strength deficit is 0.0084M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.0560M, the alkalinity of the electro-reduction effluent is 1.1752M, the chlorine absorption effluent alkalinity is 0.9428M, the nitrate content of the electro-oxidation effluent is 0.0026M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.005M.

Example 10

Treating a water sample: simulating nitrate-containing wastewater, class A, nitrate degree of 0.1429M (nitrate nitrogen of 2000mg/L), desalting load of 0, chlorinity of 0.98M, acidity of 0.13M and alkalinity of 0.

An electrolytic cell: single groove, electrode area 2500cm²。

The treatment method comprises the following steps: equal volume batch treatment.

Processing load: 25L.

Electric quantity intensity: 103.1 kC/L.

The specific operation of the treatment of the water sample is as follows:

as shown in FIG. 3, the valves 3, 8, 10 and 37 related to pretreatment are closed, and any raw water is not pretreated before entering the cathodic electroreduction treatment. The valves 33 and 35 are opened, the valves 32 and 36 are closed, and then the raw water with the first volume of 25L is pumped into the cathode circulation pipeline from the valve 33 by the cathode circulation pump 34. The volume of the first anodic electrooxidation water sample is 25L, and sodium hydroxide and sodium chloride are respectively added into deionized water according to the anode alkali-blending strength of 0.8566M and the anode salt-blending strength of 0.5M for preparation. After the anode water sample is prepared, an anode circulating pump is used for pumping the water from an anode starting water inlet pipe 76 into an anode circulating pipeline, valves 27, 39 and 74 are closed during injection, and valves 73 and 39 are opened after the injection is finished.

When the first batch of cathode and anode water samples are injected completely, the direct current power supply 31 is turned on for electrolysis, and the average current is 216.9A. The average voltage is 3.32V, the electrolysis time is 3.3h, and the cathode and anode water samples circularly flow in respective circulating pipelines under the driving of respective circulating pumps in the electrolysis process. The gas generated by the cathode and anode reactions in the first electrolysis process is exhausted, and the gas generated by the cathode electroreduction reaction in each later electrolysis process is treated in the same way. While the first electrolysis is performed, the same procedure as for preparing the anodic water sample for the first electrolysis is repeated once, and the anodic water sample is prepared for the second electrolysis. After the first electrolysis is finished, opening the valve 27 to directly drain the anode water sample, and then injecting a second batch of prepared electrooxidation water sample into the anode circulating pipeline according to the same operation as the first electrolysis; the valve 35 is closed, the valve 36 is opened, the cathode circulating pump 31 is used for pumping the water sample after the first batch of electroreduction treatment into the chlorine absorption tank 28, the valve 29 is closed before pumping, the circulation of each batch of electroreduction effluent from the cathode circulating pipeline to the chlorine absorption tank is treated in the same way, and 25L of second batch of raw water is injected into the cathode circulating pipeline according to the first cathode water sample injection operation after the circulation is finished. When the water samples of the cathode and the anode for the second electrolysis are injected into the respective circulation pipelines, the second electrolysis is started, the operation and control of the second electrolysis and each subsequent electrolysis are the same as those of the first electrolysis, and the voltage, the current and the time of the second electrolysis are the same as those of the first electrolysis. The chlorine-oxygen mixed gas generated by the anode reaction in the second electrolysis process is conveyed to a water sample in a chlorine absorption tank through a pipeline 24, the chlorine in the chlorine-oxygen mixed gas is absorbed by alkaline water, the residual oxygen and the newly generated nitrogen are discharged, the chlorine-oxygen mixed gas generated in the subsequent electro-oxidation process of each batch of water samples is processed in the same way, and the tail gas and the newly generated nitrogen after the chlorine absorption are processed in the same way.

After the second electrolysis, the valve 27 is opened to directly discharge the anode water sample, the valve 27 is closed after the discharge, the valve 29 is opened to discharge the effluent water after the chlorine absorption into the anode circulating tank 30, then the electroreduction effluent water after the second electrolysis flows into the chlorine absorption tank from the cathode circulating pipeline, the third raw water flows into the cathode circulating pipeline, after the flow, the cathode and anode water samples become raw water derivatives, and the treatment process starts to enter a stabilization stage. In the stable stage, the average voltage of the batch treatment is 3.3V, the average current is 216.9A, and the electrolysis time is 3.3 h. In the stabilization phase, three water samples were in different treatment states: electroreduction, chlorine absorption and electrooxidation. The final effluent nitre and nitrogen removal rate is 90.9 percent, and the content of the hypochlorous is less than 0.005M.

Control criterion parameters: the electromigration degree is 1.068M, the ammonium production capacity is 0.0671M, the highest residual alkalinity is 0.8666M, the alkali production capacity is 0, the chlorine production strength is 0.2149M, the effective chlorine degree is 0.98M, the highest anode alkali-blending strength is 0.8666M, and the anode alkali-blending strength deficit is 0.01M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.0671M, the alkalinity of the electro-reduction effluent is 1.1357M, the chlorine absorption effluent alkalinity is 0.8566M, the nitrate content of the electro-oxidation effluent is 0.013M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.005M.

Example 11

Treating a water sample: simulating acidic nitrate-containing wastewater, class A, the nitrate degree of 0.1429M (nitrate nitrogen of 2000mg/L), the desalting load of 0, the chloride degree of 0.552M, the acidity of 0.132M and the alkalinity of 0.

An electrolytic cell: 10-groove series galvanic pile, single-groove electrode area 2300cm²The reactor volume was 5.5L.

The treatment method comprises the following steps: constant flow continuous flow.

Processing load: 83.3L/h.

Electric quantity intensity: 95.0 kC/L.

The specific operation of the treatment of the water sample is as follows:

the treatment system is shown in fig. 4, as there is no pretreatment process for the sampled water, valves 3, 59, 10 and 8 are closed and valves 4 and 9 are opened. At the beginning of the starting stage, raw water is used for filling the cathode chamber 15 and the previous pipelines, valves 63 and 71 are opened during the water filling operation, valves 62 and 70 are closed, sodium hydroxide and sodium chloride are respectively added into deionized water according to the anode alkali mixing intensity of 0.7626M and the anode salt mixing intensity of 0.5M to prepare an anode water sample, the anode chamber 22 is filled with the prepared anode, the anode starting water inlet pipe 76 is started, valves 64, 74 and 75 are closed during the water filling operation, and valves 67, 72 and 73 are opened.

After the preparation work is finished, after the two water filling operations are finished, the cathode water inlet pump 18 and the anode starting water inlet pump are used for respectively driving the cathode water sample and the anode water sample to flow according to the flow of 83.3L/h, the direct-current power supply is started for electrolysis when the flow starts, the preparation speed of the anode water sample after the start meets the requirement of the water flow, the average electrolytic voltage is 32.6V, and the average current is 220A. The amounts of cathode and anode water flowing during the electrolysis were discharged from the cathode and anode start-up drain pipes 65 and 66, respectively, and 5min after the start of the electrolysis, the valves 62 and 64 were opened, the valves 63 and 67 were closed, and the valves 59, 80 and 27 were closed and the valve 78 was opened. The operation is continued until the water level in the cathode gas-liquid separation tank reaches the level of the start overflow pipe b79, the start overflow pipe b starts to discharge water, then the valves 78 and 75 are closed, and the valves 80, 58 and 60 are opened, before the water level in the anode gas-liquid separation tank reaches the steady-stage water level, and the valve 27 is opened. When the cathode electroreduction effluent water flow reaches the chlorine absorption tank, the valve 57 is opened, when the overflow pipe a61 is started to start water outlet, the valves 60 and 73 are closed, the valve 75 is opened, the valve 73 is closed, the anode starts the water inlet pump 77, then, the supply of the anode for preparing the water sample is stopped, the anode chamber water inlet is connected with the raw water derived water sample, and the system enters a stabilization stage.

In the stable stage, the water surfaces in the cathode gas-liquid separation tank, the anode tail gas separation tank and the anode gas-liquid separation tank are kept stable, and the pretreated water sample passes through the cathode chamber, the cathode gas-liquid separation tank, the chlorine absorption pipe, the anode tail gas separation tank, the anode chamber and the anode gas-liquid separation tank in sequence at a constant flow rate under the driving of the cathode water inlet pump, and is discharged from the anode gas-liquid separation tank. The final effluent nitre and nitrogen removal rate is 92.4 percent, and the effluent hypochlorous content is less than 0.01M.

Control criterion parameters: the electromigration degree is 0.9849M, the ammonium production capacity is 0.0674M, the highest residual alkalinity is 0.7828M, the alkali production capacity is 0, the chlorine production strength is 0.2223M, the effective chlorine degree is 0.552M, the highest anode alkali-blending strength is 0.7828M, and the anode alkali-blending strength shortage is 0.0202M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.0674M, the alkalinity of the electro-reduction effluent is 1.0522M, the chlorine absorption effluent alkalinity is 0.7626M, the nitrate content of the electro-oxidation effluent is 0.011M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.01M.

Example 12

Treating a water sample: simulating acidic nitrate-containing wastewater, B type, nitrate degree of 0.1429M (nitrate nitrogen of 2000mg/L), desalting load of 0, chlorinity of 0.074M, acidity of 0.074M and alkalinity of 0.

An electrolytic cell: 10-groove series galvanic pile, single-groove electrode area 2300cm²The reactor volume was 5.5L.

The treatment method comprises the following steps: constant flow continuous flow.

Processing load: 41.7L/h.

Electric quantity intensity: 140.4 kC/L.

The specific operation of the treatment of the water sample is as follows:

the processing system is shown in fig. 4. During pretreatment, valves 3, 59 and 9 are closed and valves 4, 8 and 10 are opened. When the starting stage begins, firstly, hydrochloric acid is supplemented to raw water in the water storage tank 17 according to the acid supplementing strength of 0.0586M for pretreatment, the acid supplementing is completed through the material supplementing opening 16, then, pretreated outlet water is filled in the cathode chamber 15 and the previous pipeline, and during the water filling operation, the valves 63 and 71 are opened, and the valves 62 and 70 are closed. Simultaneously, deionized water is respectively added with sodium hydroxide and sodium chloride according to the anode alkali mixing intensity of 1.3553M and the anode salt mixing intensity of 0.5M to prepare an anode water sample, then the anode chamber 22 is filled with the water sample, the anode starting water inlet pipe 76 is filled with the water sample, the valves 64, 74 and 75 are closed during water filling operation, and the valves 67, 72 and 73 are opened.

After the preparation work is finished, after the two water filling operations are finished, the cathode water inlet pump 18 and the anode starting water inlet pump 77 are used for respectively driving the cathode and anode water samples to flow according to the flow rate of 41.7L/h, the direct-current power supply is started for electrolysis when the flow begins, and the pretreatment speed after the start meets the water flow rate requirement, the average electrolysis voltage is 31V, and the average current is 162.5A. The amounts of cathode and anode water flowing during the electrolysis were discharged from the cathode and anode start-up drains 65 and 66, respectively, and 9min after the start of the electrolysis, valves 62 and 64 were opened, valves 63 and 67 were closed, and valves 59, 80 and 27 were closed and valve 78 was opened. The operation is continued until the water level in the cathode gas-liquid separation tank reaches the level of the start overflow pipe b79, the start overflow pipe b starts to discharge water, then the valves 78 and 75 are closed, and the valves 80, 58 and 60 are opened, before the water level in the anode gas-liquid separation tank reaches the steady-stage water level, and the valve 27 is opened. When the cathode electroreduction effluent water flow reaches the chlorine absorption tank, the valve 57 is opened, when the overflow pipe a61 is started to start water outlet, the valves 60 and 73 are closed, the valve 75 is opened, the valve 73 is closed, the anode starts the water inlet pump 77, then, the supply of the anode for preparing the water sample is stopped, the anode chamber water inlet is connected with the raw water derived water sample, and the system enters a stabilization stage.

In the stable stage, the water surfaces in the cathode gas-liquid separation tank, the anode tail gas separation tank and the anode gas-liquid separation tank are kept stable, and the pretreated water sample passes through the cathode chamber, the cathode gas-liquid separation tank, the chlorine absorption pipe, the anode tail gas separation tank, the anode chamber and the anode gas-liquid separation tank in sequence at a constant flow rate under the driving of the cathode water inlet pump, and is discharged from the anode gas-liquid separation tank. The final effluent nitre and nitrogen removal rate is 92.8 percent, and the effluent hypochlorous content is less than 0.012M.

Control criterion parameters: the electromigration degree is 1.4549M, the ammonium production capacity is 0.0256M, the highest residual alkalinity is 1.3783M, the alkali production capacity is 0.0586M, the chlorine production strength is 0.0996M, the effective chlorine degree is 0.1326M, the highest anode alkali distribution strength is 1.3783M, and the anode alkali distribution strength deficit is 0.023M.

Effluent water quality parameters: the effluent nitrate degree of electroreduction is 0, the ammonia nitrogen concentration of the effluent electroreduction is 0.0256M, the alkalinity of the effluent electroreduction is 1.4805M, the effluent alkalinity of chlorine absorption is 1.3553M, the nitrate degree of the effluent electro-oxidation is 0.0103M, the ammonia nitrogen content of the effluent electro-oxidation is 0, and the hypochlorous content of the effluent electro-oxidation is less than 0.012M.

Example 13

Treating a water sample: simulating calcium-magnesium nitrate-containing wastewater, C type wastewater, nitrate degree of 0.1429M (nitrate nitrogen of 2000mg/L), desalting load of 0.15M, chlorinity of 0.94M, acidity of 0.04M and alkalinity of 0.

An electrolytic cell: 10-groove series galvanic pile, single-groove electrode area 2300cm²The reactor volume was 5.5L.

The treatment method comprises the following steps: constant flow continuous flow.

Processing load: 41.7L/h.

Electric quantity intensity: 163.1 kC/L.

The specific operation of the treatment of the water sample is as follows:

the treatment system is shown in fig. 4, with valves 4, 8, 9 closed, valve 10 open, valves 3, 5, 13 open or closed according to time variation, valve 59 open during settling, and closed and open as required during start-up. The two sets of pretreatment devices are alternately used (only one is shown in the figure) as long as the stable treatment flow can be provided for downstream treatment.

At the beginning of the starting stage, raw water is injected into the neutralization and precipitation tank 12, alkali-supplementing precipitation is carried out on the raw water according to the initial alkali-supplementing strength of 0.19M, an alkali-supplementing agent is sodium hydroxide, precipitation treatment and alkali supplementation are completed through an alkali-supplementing opening 1, precipitated and filtered effluent is stored in a water storage tank 17, and hydrochloric acid is supplemented through an acid-supplementing opening 16 according to the initial acid-supplementing strength of 0.2041M. The pretreated effluent is filled in the cathode chamber 15 and the previous pipeline, and the valves 63 and 71 are opened and the valves 62 and 70 are closed during the cathode water filling operation. During the starting stage, the anode water sample is prepared by adding sodium hydroxide and sodium chloride by using deionized water according to the anode alkali-blending strength of 1.5501M and 0.5M respectively, then the anode chamber 22 and the anode starting water inlet pipe 76 are filled with the prepared water sample, the valves 64, 74 and 75 are closed during the anode water filling operation, and the valves 67, 72 and 73 are opened.

After the preparation is finished, the cathode water inlet pump 18 and the anode water inlet pump 77 are used for driving the cathode and anode water samples to flow according to the flow rates of 48L/h and 41.7L/h respectively, the direct-current power supply is started for electrolysis while the flow starts, the pretreatment system can provide cathode pretreatment effluent according to the required flow rate in the electrolysis process, the anode water distribution can be conveyed according to the required flow rate, the electrolysis treatment load is 48L/h, the average voltage is 31V, and the average current is 217.1A. The amounts of cathode and anode water flowing during the electrolysis were discharged from the cathode and anode start-up drains 65 and 66, respectively, and 9min after the start of the electrolysis, valves 62 and 64 were opened, valves 63 and 67 were closed, and valves 59, 80 and 27 were closed and valve 78 was opened. The operation is continued until the water level in the cathode gas-liquid separation tank 11 reaches the level of the start overflow pipe b79, the start overflow pipe b79 starts to discharge water, then the valves 78, 75 are closed, the valves 80, 58, 59, 60 are opened, before these operations, the neutralization settling tank 12 and the filter 6 of one set in the pretreatment device are emptied, the valves 3, 5, 13 thereof are closed, the reuse water reaches the neutralization settling tank 12 of the other set, the pretreatment is replaced by the same, the valve 3 thereof is opened, and the valves 5, 13 are closed or opened as required. When the valve 80 is opened, the water flow which is transported downstream through the valve 80 reaches the chlorine absorption pipe 19, the valve 57 is opened (the previous chlorine generated by the anode is directly discharged outside through the valve 81, and the valve 81 is closed when the chlorine absorption is started), when the water surface in the anode tail gas separation tank reaches the level of the starting overflow pipe a61, the constant flow water outlet is started through the starting overflow pipe a61, and then the water outlet is continued to wait for the completion of the pretreatment and other related operations. The flow rate of water supplied downstream thereof through the valve 80 was maintained at 41.7L/h, while water was continuously supplied downstream thereof through the valve 59, the flow rate was maintained at 6.3L/h. When the recycled water flow reaches the pretreatment system, the flow of the pretreated raw water is reduced to 41.7L/h from the previous 48L/h, the recycled water starts to participate in the pretreatment, the sodium hydroxide is stopped to be supplemented, but hydrochloric acid needs to be supplemented to the precipitated and filtered effluent according to the stable acid-supplementing strength of 0.0141M, and the hydrochloric acid is supplemented from the material supplementing port 16. After the pretreatment is carried out for a while using the reuse water, if the pretreatment effluent velocity reaches a steady and continuous flow rate of 48L/h, the effluent is supplied downstream from the valve 10 instead of the pretreatment effluent that was not carried out using the reuse water, and the fresh effluent flows to the cathode chamber following the old effluent. Once the new water flow reaches the inlet of the cathode chamber, the valves 73 and 70 are closed, the anode starts the water inlet pump 77, the valve 72 is opened, the anode water sample which is in a waiting state before is used for replacing the prepared alkaline saline water to convey water to the anode chamber, and the flow rate is still 41.7L/h. After 7min after the anode water flow is switched, when the new water flows of the cathode and the anode reach the outlet of the cathode chamber or the anode chamber, the valves 62 and 64 are immediately closed, the valves 63 and 67 are opened, the water supply to the downstream of the cathode chamber and the anode chamber is temporarily stopped, and the water outlet of the cathode chamber and the anode chamber is respectively discharged from the water outlet pipes 65 and 66. The output current of the DC power supply 21 is reduced from original 217.1A to 188.8A while the switching operation of the valves is executed, and after the current is adjusted for 8min, the valves 62 and 64 are opened, the valves 63 and 67 are closed, the water supply to the downstream of the cathode chamber and the anode chamber is resumed, and the system enters a stabilization treatment stage.

In the stable stage, the water surfaces in the cathode gas-liquid separation tank, the anode tail gas separation tank and the anode gas-liquid separation tank are kept stable, after a pretreated water sample passes through the cathode chamber and the cathode gas-liquid separation tank in a constant flow sequence under the driving of the cathode water inlet pump, part of water flow passes through the chlorine absorption pipe, the anode tail gas separation tank, the anode chamber and the anode gas-liquid separation tank in a constant flow sequence, water is discharged from the anode gas-liquid separation tank, and the other part of water flow enters the pretreatment system in a constant flow manner, participates in the pretreatment process, and becomes one part of water flow entering the cathode chamber after the pretreatment is completed. The final removal rate of effluent nitre and nitrogen is 95.8 percent, and the effluent hypochlorous content is less than 0.018M.

Control criterion parameters: the electromigration degree is 1.69M, the ammonium generating capacity is 0.1192M, the highest residual alkalinity is 1.3324M, the alkali generating capacity is 0.1641M, the chlorine generating strength is 0.3934M, the effective chlorine degree is 0.9541M, the highest anode alkali matching strength is 1.5859M, and the anode alkali matching strength shortage is 0.0358M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.1192M, the alkalinity of the electro-reduction effluent is 1.8092M, the chlorine absorption effluent alkalinity is 1.2966M, the nitrate content of the electro-oxidation effluent is 0.0102M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.018M.

Example 14

Treating a water sample: simulating calcium-magnesium nitrate-containing wastewater, C type wastewater, nitrate degree of 0.1429M (nitrate nitrogen of 2000mg/L), desalting load of 0.15M, chlorinity of 1.17M, acidity of 0.04M and alkalinity of 0.

An electrolytic cell: 10-groove series galvanic pile, single-groove electrode area 2300cm²The reactor volume was 5.5L.

The treatment method comprises the following steps: constant flow continuous flow.

Processing load: 40.3L/h.

Electric quantity intensity: 189.7 kC/L.

The specific operation of the treatment of the water sample is as follows:

the treatment system is shown in fig. 4, with valves 4, 8, 9 closed, valve 10 open, valves 3, 5, 13 open or closed according to time variation, valve 59 open during settling, and closed and open as required during start-up. The two sets of pretreatment devices are alternately used (only one is shown in the figure) as long as the stable treatment flow can be provided for downstream treatment.

At the beginning of the starting stage, raw water is injected into the neutralization and precipitation tank 12, alkali-supplementing precipitation is carried out on the raw water according to the initial alkali-supplementing strength of 0.19M, an alkali-supplementing agent is sodium hydroxide, precipitation treatment and alkali supplementation are completed through an alkali-supplementing opening 1, precipitated and filtered effluent is stored in a water storage tank 17, and hydrochloric acid is supplemented through an acid-supplementing opening 16 according to the initial acid-supplementing strength of 0.1346M. The pretreated effluent is filled in the cathode chamber 15 and the previous pipeline, and the valves 63 and 71 are opened and the valves 62 and 70 are closed during the cathode water filling operation. In the starting stage, sodium hydroxide and sodium chloride are added into the anode water sample by using deionized water according to the anode alkali mixing strength of 1.97M and 0.5M respectively to prepare the anode water sample, then the anode chamber 22 and the anode starting water inlet pipe 76 are filled with the prepared water sample, the valves 64, 74 and 75 are closed, and the valves 67, 72 and 73 are opened during the anode water filling operation.

After the preparation is finished, the cathode water inlet pump 18 and the anode water inlet pump 77 are used for driving the cathode and anode water samples to flow according to the flow of 45.5L/h and 40.3L/h respectively, the direct-current power supply is started for electrolysis when the flow starts, the pretreatment system can provide cathode pretreatment effluent according to the required flow in the electrolysis process, the anode water distribution can be conveyed according to the required flow, the electrolysis treatment load is 45.5L/h, the average voltage is 32.5V, and the average current is 240.1A. The amounts of cathode and anode water flowing during the electrolysis were discharged from the cathode and anode start-up drain pipes 65 and 66, respectively, and 10min after the start of the electrolysis, the valves 62 and 64 were opened, the valves 63 and 67 were closed, and the valves 59, 80 and 27 were closed and the valve 78 was opened. The operation is continued until the water level in the cathode gas-liquid separation tank 11 reaches the level of the start overflow pipe b79, the start overflow pipe b79 starts to discharge water, then the valves 78, 75 are closed, the valves 80, 58, 59, 60 are opened, before these operations, the neutralization settling tank 12 and the filter 6 of one set in the pretreatment device are emptied, the valves 3, 5, 13 thereof are closed, the reuse water reaches the neutralization settling tank 12 of the other set, the pretreatment is replaced by the same, the valve 3 thereof is opened, and the valves 5, 13 are closed or opened as required. When the valve 80 is opened, the water flow which is transported downstream through the valve 80 reaches the chlorine absorption pipe 19, the valve 57 is opened (the previous chlorine generated by the anode is directly discharged outside through the valve 81, and the valve 81 is closed when the chlorine absorption is started), when the water surface in the anode tail gas separation tank reaches the level of the starting overflow pipe a61, the constant flow water outlet is started through the starting overflow pipe a61, and then the water outlet is continued to wait for the completion of the pretreatment and other related operations. The flow rate of water supplied downstream thereof through the valve 80 was maintained at 40.3L/h, while water was continuously supplied downstream thereof through the valve 59, the flow rate was maintained at 5.2L/h. When the recycled water flow reaches the pretreatment system, the flow of the pretreated raw water is reduced to 40.3L/h from the previous 45.5L/h, the recycled water starts to participate in the pretreatment, the pretreatment alkali-adding neutralization precipitation is changed into the stable alkali-adding intensity 0.0554M, the sodium hydroxide is supplemented, and the acid supplementation is stopped. After the pretreatment is carried out for a while using the reuse water, if the pretreatment effluent rate reaches a stable and continuous flow rate of 45.5L/h, the water is supplied from the valve 10 to the downstream side instead of the pretreatment effluent which is not carried out using the reuse water, and the new effluent flows to the cathode chamber along with the old effluent. Once the new water flow reaches the inlet of the cathode chamber, the valves 73 and 70 are closed, the anode starts the water inlet pump 77, the valve 72 is opened, the anode water sample which is in a waiting state before is used for replacing the prepared alkaline saline water to convey water to the anode chamber, and the flow rate is still 40.3L/h. After 7.3min after the anode water flow is switched, when the new water flows of the cathode and the anode reach the outlet of the cathode chamber or the anode chamber, the valves 62 and 64 are immediately closed, the valves 63 and 67 are opened, the water supply to the downstream of the cathode chamber and the anode chamber is temporarily stopped, and the water outlet of the cathode chamber and the anode chamber is respectively discharged from the water outlet pipes 65 and 66. While these valve switching operations are being performed, the output current of the dc power supply 21 is reduced from 240.1A to 212.5A, and when the current is adjusted for 9min, the valves 62 and 64 are opened, the valves 63 and 67 are closed, the supply of water to the downstream of the cathode and anode chambers is resumed, and the system enters a stabilization stage.

In the stable stage, the water surfaces in the cathode gas-liquid separation tank, the anode tail gas separation tank and the anode gas-liquid separation tank are kept stable, after a pretreated water sample passes through the cathode chamber and the cathode gas-liquid separation tank in a constant flow sequence under the driving of the cathode water inlet pump, part of water flow passes through the chlorine absorption pipe, the anode tail gas separation tank, the anode chamber and the anode gas-liquid separation tank in a constant flow sequence, water is discharged from the anode gas-liquid separation tank, and the other part of water flow enters the pretreatment system in a constant flow manner, participates in the pretreatment process, and becomes one part of water flow entering the cathode chamber after the pretreatment is completed. The final effluent nitre and nitrogen removal rate is 94.2 percent, and the effluent hypochlorous content is less than 0.018M.

Control criterion parameters: the electromigration degree is 1.966M, the ammonium generating capacity is 0.0569M, the highest residual alkalinity is 1.7552M, the alkali generating capacity is 0.0946M, the chlorine generating strength is 0.2063M, the effective chlorine degree is 1.17M, the highest anode alkali matching strength is 2.0056M, and the anode alkali matching strength deficit is 0.0356M.

Effluent water quality parameters: the nitrate content of the electro-reduction effluent is 0, the ammonia nitrogen concentration of the electro-reduction effluent is 0.0569M, the alkalinity of the electro-reduction effluent is 1.9828M, the chlorine absorption effluent alkalinity is 1.7196M, the nitrate content of the electro-oxidation effluent is 0.0083M, the ammonia nitrogen content of the electro-oxidation effluent is 0, and the hypochlorous content of the electro-oxidation effluent is less than 0.018M.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention.

Claims (9)

1. A high-salt and high-nitrate industrial wastewater treatment method is characterized by comprising the following steps:

(1) and (3) carrying out electro-reduction for removing nitrate nitrogen:

nitrate radical in the waste water is subjected to electro-reduction reaction in an electrochemical reactor to generate N₂And

and simultaneously also by-product H₂And OH^-；

(2) Chlorine absorption for removing ammonia nitrogen

Using OH generated in step (1)^-Absorb chlorine gas and

chemical oxidation is carried out to generate N₂And Cl^-；

(3) Electrooxidation oxygen evolution chlorine evolution

Utilizing Cl generated in step (2)^-And OH produced in step (1)^-Generate electric oxidationReacting to generate chlorine and oxygen, and returning the chlorine to the step (2) for absorption;

also comprises a pretreatment step of desalting or adjusting alkalinity by using the alkali generated in the step (1);

in the processing process, the method also relates to a criterion parameter, a discrimination standard, a discrimination method and three control equations for guiding the sequential circulation of the water sample among the four processing steps, and the method comprises the following specific steps:

the criterion parameters comprise desalting load, electromigration degree, ammonium production capacity, highest residual alkalinity, alkali production capacity, chlorine production strength, effective chlorine degree, highest anode alkali distribution strength and anode alkali distribution strength deficit, and the criterion standards and methods comprise water sample type judgment standards, judgment methods, and anode water sample initial batching standards and judgment methods in a starting stage;

the first control equation is a control equation of the alkalinity of the chlorine absorption inlet water: c_XJ=C^* _YJ+4

；

Wherein, C_XJChlorine absorption alkalinity, the molar concentration of hydroxide ions in the chlorine absorption influent;

C^* _YJ-the balance of the maximum residual alkalinity, the maximum value of the residual alkalinity, the electromigration minus three times the capacity for producing ammonium;

-ammonium production capacity, handling the moles of ammonium ions produced in 1 liter of the electro-hydraulic reduction process;

the second control equation is the chlorine intensity control equation of the electro-oxidation feed water: c_Cl=C^* _YJ+3

-C_YJ（0≤C_YJ≤C^* _YJ）；

Wherein, C_CChlorine production intensity, electro-oxidation treatmentThe mole number of chlorine atoms generated by 1 liter of water sample;

C^* _YJ-the balance of the maximum residual alkalinity, the maximum value of the residual alkalinity, the electromigration minus three times the capacity for producing ammonium;

-ammonium production capacity, handling the moles of ammonium ions produced in 1 liter of the electro-hydraulic reduction process;

C_YJresidual alkalinity, the molar concentration of hydroxide ions in the feed water of the electro-oxidation treatment;

the third control equation is an anode alkali-blending intensity control equation in the starting stage: c_AJ=C^* _AJX, wherein C^* _AJ=(1+r)C^* _YJ+3r

；

Wherein, C_AJThe anode alkali-blending strength, the mole number of the sodium hydroxide added for preparing 1 liter of anode water sample in the starting stage;

C^* _AJ-the highest anode base-distribution intensity, the maximum value of the anode base-distribution intensity;

x is the shortage of the anode alkali-matching strength, and the anode alkali-matching strength is smaller than the difference value of the highest anode alkali-matching strength.

2. The wastewater treatment method according to claim 1, comprising a start-up stage for preparing a raw water derivative sample for downstream treatment that can be matched to upstream treatment and satisfies conditions required for stable operation;

the anode water sample during electrolytic treatment in the starting stage is alkaline saline water, the flow of the anode water sample is equal to the load of raw water for batch treatment, and deionized water or purified water is adopted to prepare alkali according to the anode alkali strength C_AJAnd anode complex salt strength C_AYAdding sodium chloride and sodium hydroxide to prepare.

3. An equal-volume batch treatment system for implementing the high-salinity high-nitrate industrial wastewater treatment method according to claim 1 or 2, which is characterized by comprising a pretreatment system, an electrochemical treatment system and a chlorine absorption system;

the pretreatment system comprises a neutralization and sedimentation tank, a filter and a water storage tank;

the electrochemical treatment system comprises a direct current power supply, an electrochemical reactor, a cathode circulating tank and an anode circulating tank; the electrochemical reactor comprises a cathode chamber and an anode chamber, a cathode circulating pump is arranged on a pipeline between the cathode chamber and the cathode circulating tank, and an anode circulating pump is arranged on a pipeline between the anode chamber and the anode circulating tank; the cathode chamber, the cathode circulating tank, the cathode circulating pump and relevant circulating pipelines form an electroreduction treatment circulating system; the anode chamber, the anode circulating tank, the anode circulating pump and relevant circulating pipelines form an electro-oxidation treatment circulating system;

the chlorine absorption system includes a chlorine absorption tank.

4. The system as claimed in claim 3, wherein the equal volume batch processing system is driven by two pumps of a cathode circulating pump and an anode circulating pump, and is combined with the switch of the relevant valve to complete the electrochemical treatment and circulation between different treatment procedures of the water sample.

5. The system of claim 3 or 4, wherein the electrochemical reactor is a two-chamber type electrochemical reactor, the basic unit of the reactor comprising anode chamber walls, an anode, a cation exchange membrane, a cathode and cathode chamber walls; the cation exchange membrane divides the reactor into an anode chamber and a cathode chamber, an anode chamber is formed between the anode chamber wall and the cation exchange membrane, and the anode is inserted into the anode chamber; a cathode chamber is formed between the cathode chamber wall and the cation exchange membrane, and the cathode is inserted in the cathode chamber.

6. A constant flow continuous flow system for implementing the high salinity and high nitrate industrial wastewater treatment method according to any one of claims 1 to 2, which comprises a pretreatment system, an electrochemical treatment system and a chlorine absorption system;

the pretreatment system comprises a neutralization and sedimentation tank, a filter and a water storage tank;

the electrochemical treatment system comprises a direct-current power supply, an electrochemical reactor, a cathode gas-liquid separation tank, an anode tail gas separation tank and an anode gas-liquid separation tank; the electrochemical reactor comprises a cathode chamber and an anode chamber, wherein the upstream and the downstream of the cathode chamber are respectively connected with an outlet of a cathode water inlet pump and an inlet of a cathode gas-liquid separation tank, and the upstream and the downstream of the anode chamber are respectively connected with an anode tail gas separation tank and an anode gas-liquid separation tank;

the chlorine absorption system includes a chlorine absorption tank.

7. The system of claim 6, wherein a cathode water inlet pump is disposed between the water storage tank and the cathode chamber, and an anode-activated water inlet pump is disposed in connection with the inlet of the anode chamber;

the cathode gas-liquid separation tank is a high-level tank, a cathode gas discharge port and a first water sample inlet are arranged at the top of the cathode gas-liquid separation tank, and the first water sample inlet is connected with an outlet of the cathode chamber; the bottom of the cathode gas-liquid separation tank is provided with a first water sample outlet, and the water sample outlet is connected with a tee joint and respectively communicated with the neutralization precipitation tank and the chlorine absorption pipe inlet; a first starting overflow pipe is arranged at the upper part of the cathode gas-liquid separation tank;

the anode tail gas separation tank is a meso-position tank, the top of the anode tail gas separation tank is provided with a second water sample inlet, a salt supplementing pipe and an anode tail gas discharge port, and the second water sample inlet is connected with the outlet of the chlorine absorption pipe; the salt supplementing pipe is inserted into a water sample in the tank; the bottom of the anode tail gas separation tank is provided with a second water sample outlet which is connected with the inlet of the anode chamber; and a second starting overflow pipe is arranged at the upper part of the anode tail gas separation tank.

8. The system of claim 6, wherein the chlorine absorption pipe is connected upstream and downstream to the outlet of the cathode gas-liquid separation tank and the second water sample inlet of the anode tail gas separation tank, respectively; the chlorine absorption pipe is also provided with a gas inlet, and the gas inlet is connected with a gas outlet of the anode gas-liquid separation tank;

the constant flow continuous flow system respectively completes the flow circulation of a cathode water sample and the flow of an anode water sample by using a cathode water inlet pump and an anode water inlet pump in a starting stage, and completes the flow and circulation of a treated water sample in the system by using only one cathode water inlet pump in a stabilizing stage;

the constant flow continuous flow system uses two start-up overflows in the start-up phase to control and direct the constant flow and circulation of the treated water samples between the relevant intermediate treatment steps.

9. The system according to any one of claims 6 to 8, wherein the electrochemical reactor is a two-chamber type electrochemical reactor, the basic unit of which comprises an anode chamber wall, an anode, a cation exchange membrane, a cathode and a cathode chamber wall; the cation exchange membrane divides the reactor into an anode chamber and a cathode chamber, an anode chamber is formed between the anode chamber wall and the cation exchange membrane, and the anode is inserted into the anode chamber; a cathode chamber is formed between the cathode chamber wall and the cation exchange membrane, and the cathode is inserted in the cathode chamber.

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