CN115215431B - Construction method of aerobic granular sludge forming system - Google Patents
Construction method of aerobic granular sludge forming system Download PDFInfo
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical class [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 3
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- 229910052786 argon Inorganic materials 0.000 description 6
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- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 3
- 235000019270 ammonium chloride Nutrition 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
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- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
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- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
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- 239000008394 flocculating agent Substances 0.000 description 1
- 230000003311 flocculating effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1236—Particular type of activated sludge installations
- C02F3/1263—Sequencing batch reactors [SBR]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
The invention relates to the technical field of sewage treatment, and in particular discloses a construction method of an aerobic granular sludge forming system, which comprises the following steps: step 1, preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material: synthesizing and preparing the nitrogen-doped iron-carrying/graphene oxide composite conductive material by using an iron source, a nitrogen source and graphene oxide; step 2, system construction: adding nitrogen-doped iron-carrying/graphene oxide into an SBR reactor containing sludge, controlling aeration intensity, surface air speed, hydraulic load and hydraulic residence time, and culturing to construct a system containing aerobic granular sludge. According to the invention, the nitrogen-doped iron-carrying/graphene oxide composite conductive material is prepared, so that a framework is provided for the formation of the granular sludge, and the sludge aggregation and the inter-species electron transfer are promoted, so that the purpose of accelerating the formation of aerobic granular sludge is achieved.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a construction method of an aerobic granular sludge forming system based on a nitrogen-doped iron-carrying/graphene oxide composite conductive material.
Background
The biochemical process is the main process in sewage treatment, and comprises an activated sludge process and a biomembrane process, and the specific process of the traditional activated sludge process comprises CASS, oxidation ditch, A/O and A 2 /O, etc. Mishima et al, 1991, originally discovered aerobic granular sludge (Aerobic Granular Sludge, AGS) and reported the cultivation of AGS for the first time using a continuous flow aerobic upflow sludge bed reactor (Aerobic Upflow Sludge Blanket, AUSB). The aerobic granular sludge is a biological flocculating body with self-immobilized cells, has the advantages of compact structure, good sedimentation performance, strong impact resistance and the like, and has unique layered structure, so that the aerobic granular sludge has the capabilities of carbonization and nitrification denitrification, the carbon and nitrogen removal and phosphorus removal processes of sewage are greatly shortened, and the application prospect is wide. Although the effectiveness of aerobic granular sludge is widely accepted, there is a bottleneck that affects its engineering implementation: firstly, the culture speed of the granular sludge is slow; secondly, the particles are easy to disintegrate due to sludge cavitation, and the particles are difficult to use especially in town sewage with wide time-varying characteristics; thirdly, the aerobic granular sludge technology has the characteristics of high energy consumption, intermittent operation, unfavorable amplification and the like.
The optimization of the aerobic granular sludge at present mainly starts from the two aspects of accelerating the formation process of the aerobic granular sludge and strengthening the stability of the aerobic granular sludge. The method for accelerating the formation process of the aerobic granular sludge mainly comprises the following steps: 1. adding auxiliary materials or changing the components of inoculated sludge (metal ions, flocculating agents, mature granular sludge and the like); 2. regulating the operating conditions (reducing ST, extending starvation time, increasing shear force, increasing OLR, etc.); 3. coupling select pressure (coupling strong hydraulic select pressure and high load operation mode, etc.). The reason for the destabilization of the aerobic granular sludge mainly comprises mass propagation of filamentous bacteria, hydrolysis of the anaerobic kernel of the granules, loss of functional bacteria and change of EPS components. Current strategies for enhancing the stability of aerobic granular sludge during long-term operation mainly include: providing suitable operating conditions, screening for microorganisms with a slow growth rate, inhibiting anaerobic activity within the particles, and strengthening the particle core. However, the existing aerobic granular sludge culture process has the problems of poor structural stability and the like caused by excessive proliferation of filamentous bacteria and endogenous respiration of microorganisms, and the problem of reduced granular stability of the aerobic granular sludge in long-term operation.
Disclosure of Invention
Aiming at some problems existing in the current aerobic granular sludge, the invention provides a construction method of an aerobic granular sludge forming system based on a nitrogen-doped iron-carrying/graphene oxide composite conductive material, which adopts the nitrogen-doped iron-carrying/graphene oxide composite conductive material to enable the nitrogen-doped iron-carrying/graphene oxide composite conductive material to have certain mechanical strength, conductivity, porosity and adsorption characteristics, and takes the nitrogen-doped iron-carrying/graphene oxide composite conductive material as a core so as to achieve rapid construction of the aerobic granular sludge forming system.
The aim of the invention is realized by adopting the following technical scheme:
the construction method of the aerobic granular sludge forming system comprises the following steps:
step 1, preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
synthesizing and preparing the nitrogen-doped iron-carrying/graphene oxide composite conductive material by using an iron source, a nitrogen source and graphene oxide;
step 2, system construction:
adding nitrogen-doped iron-carrying/graphene oxide into an SBR reactor containing sludge, controlling aeration intensity, surface air speed, hydraulic load and hydraulic residence time, and culturing to construct a system containing aerobic granular sludge.
Preferably, in the step 1, the preparation method of the nitrogen doped iron-carrying/graphene oxide composite conductive material is a hydrothermal synthesis method or a high-temperature synthesis method.
Preferably, in the step 1, the iron source of the hydrothermal synthesis method is ferric chloride hexahydrate, and the nitrogen source is urea.
Preferably, in the step 1, the iron source of the high-temperature synthesis method is ferric chloride hexahydrate, and the nitrogen source is ammonia or nitrogen.
Preferably, in the step 1, the conductivity of the nitrogen-doped iron-carrying/graphene oxide composite conductive material is (1-10) x 10 6 S/m.
Preferably, in the step 2, the sludge is flocculent sludge which is recovered from an aerobic section of a biochemical process of the sewage plant and subjected to aeration domestication for two days.
Preferably, in the step 2, the aeration intensity is 2.7L/min, the surface air speed is 1cm/s, the hydraulic retention time is 4h, and the hydraulic load is 3m 3 /(m 3 ·d)。
Preferably, in the step 2, the culturing time is 15-30 days.
Preferably, in the step 2, the concentration of the nitrogen doped iron-carrying/graphene oxide added into the sludge is 400mg/L.
Preferably, in the step 2, the SBR reactor has specific operating parameters of: the reactor had an aspect ratio of 9, an inner diameter of 7.5cm, a height of 67.5cm and an effective volume of 3L.
Preferably, in the step 2, the SBR cultures the aerobic granular sludge by adopting a method of gradually shortening the sludge settling time (15 min-10 min-5 min).
Preferably, in the step 2, the total period length of the SBR reactor is 240min, the SBR reactor is operated for 6 periods a day, and 50% of the initially added amount of the nitrogen-doped iron-carrying/graphene oxide composite conductive material is replenished during the replacement period.
Preferably, in the step 2, the concentration of the aerobic granular sludge formed by culture is more than 6000 mg/L.
Preferably, in the step 2, the particle size distribution of the aerobic granular sludge is 0.4-1.5mm, and the density is 1.0078-1.0380g/cm 3 。
Preferably, the process for synthesizing the nitrogen-doped iron-carrying/graphene oxide composite conductive material by using a hydrothermal synthesis method comprises the following steps of:
(1) Preparing precursor urea iron:
dissolving urea in absolute ethyl alcohol, adding ferric chloride hexahydrate after the urea is completely dissolved, reacting for 2 hours under magnetic stirring to generate light green urea-iron complex precipitate, filtering at normal pressure, washing for a plurality of times with absolute ethyl alcohol, and drying in a drying oven to obtain precursor urea-iron; wherein the mass ratio of the ferric chloride hexahydrate to the urea is 0.5-1:1; the conductivity of the material is enhanced along with the increase of the content of ferric chloride hexahydrate and nitrogen, and the adsorptivity of the material is enhanced along with the increase of the content of graphene;
(2) Preparing graphene oxide-ammonia water mixed solution:
adding 30mL of ammonia water into 50mL of graphene oxide with the concentration of 7mg/mL, uniformly mixing under magnetic stirring, and performing ultrasonic treatment for a certain time to obtain graphene oxide-ammonia water mixed solution;
(3) Preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
dissolving 0.5-2g of precursor urea iron in 30mL of ethylene glycol, adding 0.2g of PVP (dispersing agent), adding into graphene oxide-ammonia water mixed solution after PVP is completely dissolved, adjusting pH=11 with saturated sodium hydroxide aqueous solution, magnetically stirring and ultrasonically treating to obtain uniform mixed solution, transferring the mixed solution into a 200mL reaction kettle, and placing into a 200 ℃ oven for reacting for a certain time; after the reaction is finished, cooling to room temperature, collecting a product, washing the product to be neutral by distilled water, drying the product in a vacuum drying oven, and then grinding the product into a powder target product with 100-120 meshes, thus obtaining the nitrogen-doped iron-carrying/graphene oxide.
Preferably, the process for synthesizing the nitrogen-doped iron-carrying/graphene oxide composite conductive material by using a high-temperature synthesis method comprises the following steps:
(1) Weighing ferric trichloride hexahydrate, dissolving in ionized water to formFeCl 3 An aqueous solution; wherein the mass ratio of the ferric chloride hexahydrate to the deionized water is 0.2-2:1; the conductivity of the material is enhanced along with the increase of the content of ferric chloride hexahydrate and nitrogen, and the adsorptivity of the material is enhanced along with the increase of the content of graphene;
(2) Will 4mLFECl 3 Dropwise adding the aqueous solution into a beaker filled with graphene oxide dispersion liquid, and simultaneously carrying out sufficient magnetic stirring until FeCl is obtained 3 After the water solutions are respectively dripped, continuing to magnetically stir for 2 hours, and then carrying out ultrasonic treatment for 30 minutes to obtain a reaction mixed solution;
(3) Freeze-drying the reaction mixed solution to obtain aerogel, placing the aerogel in a tubular furnace, vacuumizing the tubular furnace to remove air, performing low-vacuum high-temperature heat treatment under an ammonia atmosphere, heating at a speed of 10 ℃/min, keeping the temperature at 900 ℃ for 4 hours, cooling, taking out the product, grinding and sieving to obtain 100-120-mesh nitrogen-doped iron/graphene oxide; wherein the flow rate of the ammonia gas and the argon gas introduced in the heating and heat preservation stages is 100sccm, and the working air pressure is 500-1000 Pa; argon is only introduced into the cooling process at a speed of 15 ℃/min, wherein the argon is only introduced into the cooling process at a speed of 400 sccm.
The beneficial effects of the invention are as follows:
1. according to the method, the nitrogen-doped iron-carrying/graphene oxide composite conductive material is prepared, a framework is provided for the formation of the granular sludge, so that the aggregation of the sludge and the transmission of electrons between seeds are promoted, and the purpose of accelerating the formation of aerobic granular sludge is achieved. The nitrogen-doped iron-carrying/graphene oxide composite conductive material takes graphene oxide as a carrier, and nitrogen element and iron oxide are loaded on the surface and pore channels of the graphene oxide, so that the nitrogen-doped iron-carrying/graphene oxide composite conductive material has both the adsorptivity of the graphene oxide and the conductivity of the iron-based material, and simultaneously, the conductivity of the material is further improved due to nitrogen doping.
2. The invention constructs a rapid construction system of aerobic granular sludge based on nitrogen-doped iron-carrying/graphene oxide composite conductive material. Due to the adsorption effect and the electric conduction effect of the nitrogen-doped iron-carrying/graphene oxide composite electric conduction material, the aggregation of the sludge into large particles is accelerated, and meanwhile, the inter-species electron transfer is promoted, so that aerobic granular sludge can be formed in 15-30 days, the average particle size of the granular sludge reaches 0.6mm after 15 days of culture, and the forming time of the particles is shortened by 30-50% compared with that of the traditional aerobic granular sludge process.
3. The method is simple and convenient to operate, the preparation of the related materials is more convenient, the finished product is low, and the effect of improving the speed can be enhanced only by adding a small amount of the related materials. The formation of the aerobic granular sludge is quickened, the sewage treatment cost is effectively reduced, and the theoretical technical bottleneck of the application of the aerobic granular sludge is solved.
4. The aerobic granular sludge based on the nitrogen-doped iron-carrying/graphene oxide composite conductive material formed by the invention has the sludge concentration reaching more than 6000mg/L after being stabilized, good sedimentation performance, particle size distribution of 0.4-1.5mm and density distribution of 1.0078-1.0380g/cm 3 The average sedimentation velocity reaches 45-50m/h, and the maximum sedimentation velocity reaches more than 70 m/h; the method is improved by 20-50% compared with the conventional method.
5. The aerobic granular sludge has good stability after maturation, can resist larger hydraulic impact load and organic impact load, and has the experimental organic load of 1.395kg COD/(m) 3 D) the actual impact resistance is strong.
6. Because of the conductivity of the material, the aerobic granular sludge forming system based on the nitrogen-doped iron-carrying/graphene oxide composite conductive material has enhanced decontamination effect compared with the conventional aerobic granular sludge process, and the COD (chemical oxygen demand) of experimental inflow water is 460-550mg/L and BOD (biological oxygen demand) 5 270-330mg/L, 35-43mg/L total nitrogen and 4.4-5.2mg/L total phosphorus, and the COD of the effluent is 35mg/L on average 5 The ammonia nitrogen of the treated effluent is about 0 and the total nitrogen is less than 13mg/L, and the total phosphorus is 1.0-1.5mg/L, and the effluent can reach the first-level A emission standard except phosphorus.
7. Compared with the conventional aerobic granular sludge technology, the aeration capacity and the occupied area of the aerobic granular sludge are saved, the aeration intensity is controlled at 2.7L/min, the surface air speed is 1cm/s, and the energy consumption is saved by 10-30%.
Detailed Description
The technical features, objects and advantages of the present invention will be more clearly understood from the following detailed description of the technical aspects of the present invention, but should not be construed as limiting the scope of the invention.
In the preparation process of the nitrogen-doped iron-carrying/graphene oxide composite conductive material, according to the loading principle, the pore diameter is determined by graphene oxide; the graphene oxide is of a layered porous structure, after the iron-based material is loaded, the pore canal is filled with the iron-based material, and the porosity is reduced by 20% -80%; the specific surface area of the graphene oxide is 50-300m 2 Per gram, the specific surface area of the nitrogen-doped iron-carrying/graphene oxide composite conductive material is 5-100m 2 /g; the graphene oxide has conductivity which is between 0.1 and 1000S/m according to the C/O ratio, and the conductivity of the iron-based material is (1-10) multiplied by 10 6 The conductivity of the nitrogen-doped iron-carrying/graphene oxide composite conductive material is influenced by nitrogen doping and iron series materials between S/m, the main effect is mainly achieved, the conductivity is improved to be between 1 and 10 multiplied by 10 6 S/m.
The starting materials, reagents or apparatus used in the following examples are all available from conventional commercial sources or may be obtained by methods known in the art unless otherwise specified.
The invention will be further described with reference to the following examples.
Example 1
The construction method of the aerobic granular sludge forming system based on the nitrogen-doped iron-carrying/graphene oxide composite conductive material provided by the embodiment comprises the following steps:
step 1, preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
(1) Preparing precursor urea iron:
dissolving 7.2g of urea in 40mL of absolute ethyl alcohol, adding 5.4g of ferric chloride hexahydrate after the urea is completely dissolved, reacting for 2 hours under magnetic stirring to generate pale green urea iron complex precipitate, filtering at normal pressure, washing for a plurality of times with the absolute ethyl alcohol, and drying in an oven to obtain precursor urea iron;
(2) Preparing graphene oxide-ammonia water mixed solution:
adding 30mL of ammonia water into 50mL of graphene oxide with the concentration of 7mg/mL, uniformly mixing under magnetic stirring, and performing ultrasonic treatment for a certain time to obtain graphene oxide-ammonia water mixed solution;
(3) Preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
dissolving 0.5-2g of precursor urea iron in 30mL of ethylene glycol, adding 0.2g of PVP (dispersing agent), adding into graphene oxide-ammonia water mixed solution after PVP is completely dissolved, adjusting pH=11 with saturated sodium hydroxide aqueous solution, magnetically stirring and ultrasonically treating to obtain uniform mixed solution, transferring the mixed solution into a 200mL reaction kettle, and placing into a 200 ℃ oven for reacting for a certain time; after the reaction is finished, cooling to room temperature, collecting a product, washing the product to be neutral by distilled water, drying the product in a vacuum drying oven, and then grinding the product into a powder target product with 100-120 meshes, thus obtaining the nitrogen-doped iron-carrying/graphene oxide.
Step 2, system construction:
adding nitrogen-doped iron-carrying/graphene oxide into an SBR reactor containing sludge until the concentration of the nitrogen-carrying iron-graphene oxide is 400mg/L, the aeration strength is 2.7L/min, the surface air speed is 1cm/s, the hydraulic retention time is 4h, and the hydraulic load is 3m 3 /(m 3 D) after 15 days of culture, constructing and forming aerobic granular sludge.
Example 2
The construction method of the aerobic granular sludge forming system based on the nitrogen-doped iron-carrying/graphene oxide composite conductive material comprises the following steps:
step 1, preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
(1) 20mg of ferric trichloride hexahydrate was weighed and dissolved in 4mL of ionized water to form FeCl 3 An aqueous solution; wherein the mass ratio of the ferric chloride hexahydrate to the deionized water is 0.2-2:1; the conductivity of the material is enhanced along with the increase of the content of ferric chloride hexahydrate and nitrogen, and the adsorptivity of the material is enhanced along with the increase of the content of graphene;
(2) Will 4mLFECl 3 Dropwise adding the aqueous solution into a beaker filled with graphene oxide dispersion liquid, and simultaneously carrying out sufficient magnetic stirring until FeCl is obtained 3 After the water solutions are respectively dripped, continuing to magnetically stir for 2 hours, and then carrying out ultrasonic treatment for 30 minutes to obtain a reaction mixed solution; wherein the graphene oxide dispersion liquid is prepared by dispersing graphene oxide and a dispersing agent pvp in deionized waterIn water, the volume is 50mL, the concentration of graphene oxide is 7mg/mL, and the addition amount of a dispersing agent pvp is 0.2g;
(3) Freeze-drying the reaction mixed solution to obtain aerogel, placing the aerogel in a tubular furnace, vacuumizing the tubular furnace to remove air, performing low-vacuum high-temperature heat treatment under an ammonia atmosphere, heating at a speed of 10 ℃/min, keeping the temperature at 900 ℃ for 4 hours, cooling, taking out the product, grinding and sieving to obtain 100-120-mesh nitrogen-doped iron/graphene oxide; wherein the flow rate of the ammonia gas and the argon gas introduced in the heating and heat preservation stages is 100sccm, and the working air pressure is 500-1000 Pa; argon is only introduced into the cooling process at a speed of 15 ℃/min, wherein the argon is only introduced into the cooling process at a speed of 400 sccm.
Step 2, system construction:
adding nitrogen-doped iron-carrying/graphene oxide into an SBR reactor containing sludge until the concentration of the nitrogen-carrying iron-graphene oxide is 400mg/L, the aeration strength is 2.7L/min, the surface air speed is 1cm/s, the hydraulic retention time is 4h, and the hydraulic load is 3m 3 /(m 3 D) after 15 days of culture, constructing and forming aerobic granular sludge.
Comparative example 1
The construction method of the aerobic granular sludge forming system is similar to that of the embodiment 1, and the difference is that only the nitrogen-doped iron-carrying/graphene oxide composite conductive material is replaced by 100-mesh glass beads (inert materials) with the same amount.
Comparative example 2
The construction method of the aerobic granular sludge forming system is the same as that of the embodiment 1, except that the nitrogen-doped iron-carrying/graphene oxide composite conductive material is not added.
Among them, in examples 1-2 and comparative examples 1-2 of the present invention, SBR reactor specific operating parameters: the reactor had an aspect ratio of 9, an inner diameter of 7.5cm, a height of 67.5cm and an effective volume of 3L. The SBR system controls the whole processes of water inflow, aeration, sedimentation, water drainage and the like through a time relay, wherein specific operation parameters are water inflow for 3min, aerobic aeration (aeration is started while water inflow) for 220-230min, sedimentation for 15-10-5min, water drainage for 5min, the total period length is 240min, and the SBR system operates for 6 periods a day. SBR adopts the gradual shortening of the sludge settling time (15 min-10 min-5 m)in) culturing aerobic granular sludge. The aeration rate is controlled to be 2.7L/min by adopting an air pump and an aeration sand head to supply oxygen, and the temperature is controlled to be (25+/-2) DEG C by adopting a rotameter. Active mud discharge is not performed all the time during the operation of the reactor. The water distribution composition is as follows: sodium acetate (COD) 500mg/L, NH4Cl (NH) 4 + -N)40mg/L，KH 2 PO 4 (TP) 5mg/L, 1mL of the trace element solution was added dropwise to each 10L of the water. The inoculated sludge is flocculent sludge which is recovered from an aerobic section of a biochemical process of a sewage plant and subjected to aeration domestication for two days.
In order to more clearly illustrate the present invention, physical properties and chemical properties in the formation process of the granular sludge of example 1, comparative example 1 and comparative example 2 are continuously observed, wherein the physical properties include sludge morphology, sedimentation performance, sludge structure wet density, sludge particle size analysis and the like, and the chemical properties include sludge secretion EPS, sludge surface hydrophobicity and the like. And (3) measuring the conventional index of sewage in the SBR system every 5 days, wherein the sampling time is 5min at the end of the aeration period in the period, and taking out the supernatant which is precipitated for 5min after the sampling time is used for measuring the index of the water quality of the effluent. DO, pH and other indexes are measured by a WTW portable multi-parameter instrument.
The test results are shown in table 1 below:
TABLE 1 detection results of different well-supported sludge formation systems
| Example 1 | Comparative example 1 | Comparative example 2 | |
| COD content (mg/L) | 13-21 | 16-24 | 25-37 |
| NH 4 + -N content (mg/L) | 0 | 0 | 0 |
| TN content (mg/L) | 9-12 | 11-14 | 14-18 |
| TP content (mg/L) | 1.0-1.5 | 1.2-1.8 | 1.3-2.4 |
| Aeration DO content (mg/L) | ＞2 | ＞2 | ＞2 |
| pH | 6-8 | 6-8 | 6-8 |
| Particle sinking speed (m/h) | 45-68 | 39-58 | 35-54 |
| Average particle diameter (mm) of the particles at 65d | 0.967 | 0.836 | 0.583 |
As can be seen from Table 1, the COD content, TN content and TP content of the system of the embodiment 1 of the present invention are relatively lower, the sedimentation speed of the particles is faster, and the average particle size is larger, which indicates that the system of the embodiment 1 of the present invention has better stability of the itching-relieving granular sludge, and better degradation effect on COD, TN and TP.
Other embodiments of the formation of other components, ratios and process parameters are selected within the ranges of the components, ratios and process parameters described in the present invention, and the technical effects of the present invention can be achieved, so they are not listed one by one.
According to the embodiment of the invention, the nitrogen-doped iron-carrying/graphene oxide composite conductive material is prepared, so that a framework is provided for forming the granular sludge, and the sludge aggregation and inter-species electron transfer are promoted, so that the purpose of accelerating the formation of aerobic granular sludge is achieved.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (6)
1. The construction method of the aerobic granular sludge forming system is characterized by comprising the following steps:
step 1, preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material:
the nitrogen-doped iron-carrying/graphene oxide composite conductive material is prepared by using an iron source, a nitrogen source and graphene oxide through a hydrothermal synthesis method or a high-temperature synthesis method, wherein the process of synthesizing the nitrogen-doped iron-carrying/graphene oxide composite conductive material through the hydrothermal synthesis method comprises the following steps:
(1) Preparing precursor urea iron: dissolving urea in absolute ethyl alcohol, adding ferric chloride hexahydrate after the urea is completely dissolved, reacting for 2 hours under magnetic stirring to generate light green urea-iron complex precipitate, filtering at normal pressure, washing for a plurality of times with absolute ethyl alcohol, and drying in a drying oven to obtain precursor urea-iron; wherein the mass ratio of the ferric chloride hexahydrate to the urea is 0.5-1:1;
(2) Preparing graphene oxide-ammonia water mixed solution: adding 30mL of ammonia water into 50mL of graphene oxide with the concentration of 7mg/mL, uniformly mixing under magnetic stirring, and performing ultrasonic treatment for a certain time to obtain graphene oxide-ammonia water mixed solution;
(3) Preparing a nitrogen-doped iron-carrying/graphene oxide composite conductive material: dissolving 0.5-2g of precursor urea iron in 30mL of ethylene glycol, adding 0.2g of PVP dispersing agent, adding the mixture into graphene oxide-ammonia water mixed solution after PVP is completely dissolved, adjusting pH=11 with saturated sodium hydroxide aqueous solution, magnetically stirring and uniformly mixing by ultrasound, transferring into a 200mL reaction kettle, and placing into a 200 ℃ oven for reacting for a certain time; after the reaction is finished, cooling to room temperature, collecting a product, washing the product to be neutral by distilled water, drying the product in a vacuum drying oven, and grinding and sieving the product to obtain a powdery target product with 100-120 meshes, thus obtaining the nitrogen-doped iron-carrying/graphene oxide composite conductive material;
the process for synthesizing the nitrogen-doped iron-carrying/graphene oxide composite conductive material by using a high-temperature synthesis method comprises the following steps:
(1) Weighing ferric trichloride hexahydrate, dissolving in ionized water to form FeCl 3 An aqueous solution; wherein the mass ratio of the ferric chloride hexahydrate to the deionized water is 0.2-2:1;
(2) Will 4mLFECl 3 Dropwise adding the aqueous solution into a beaker filled with graphene oxide dispersion liquid, and simultaneously carrying out sufficient magnetic stirring until FeCl is obtained 3 After the water solutions are respectively dripped, continuing to magnetically stir for 2 hours, and then carrying out ultrasonic treatment for 30 minutes to obtain a reaction mixed solution;
(3) Freeze-drying the reaction mixed solution to obtain aerogel, placing the aerogel in a tubular furnace, vacuumizing the tubular furnace to remove air, performing low-vacuum high-temperature heat treatment under ammonia or nitrogen atmosphere, heating at a speed of 10 ℃/min, keeping the temperature for 4 hours at a target temperature of 900 ℃, cooling, taking out the product, grinding and sieving to obtain the 100-120-mesh nitrogen-doped iron-carrying/graphene oxide composite conductive material;
step 2, system construction:
adding the nitrogen-doped iron-carrying/graphene oxide composite conductive material with the concentration of 400mg/L into an SBR reactor containing sludge, controlling aeration intensity, surface air speed, hydraulic load and hydraulic residence time, and culturing to construct a system containing aerobic granular sludge.
2. The method for constructing an aerobic granular sludge formation system according to claim 1, wherein in the step 1, the conductivity of the nitrogen doped iron carrier/graphene oxide composite conductive material is (1-10) x 10 6 S/m.
3. The method according to claim 1, wherein in the step 2, the sludge is a flocculated sludge obtained after two days of aeration acclimation and recovered from an aerobic section of a biochemical process of a sewage plant.
4. The method according to claim 1, wherein in the step 2, the aeration intensity is 2.7L/min, the surface air velocity is 1cm/s, the hydraulic retention time is 4h, and the hydraulic load is 3m 3 /(m 3 ·d)。
5. The method of claim 1, wherein the cultivation time in the step 2 is 15 to 30 days.
6. The method for constructing an aerobic granular sludge formation system according to claim 1, wherein in the step 2, the aerobic granular sludge has a particle size distribution of 0.4 to 1.5mm and a density of 1.0078 to 1.0380g/cm 3 。
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| CN114368831A (en) * | 2022-01-27 | 2022-04-19 | 石河子大学 | Composite material for accelerating formation of aerobic granular sludge, preparation method and application |
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