CN108275846B

CN108275846B - Anthraquinone wastewater treatment method

Info

Publication number: CN108275846B
Application number: CN201810240333.XA
Authority: CN
Inventors: 丁兴成; 高立江; 陈海滨; 陈宝兴
Original assignee: Zhejiang Runtu Institute Co ltd
Current assignee: Zhejiang Runtu Institute Co ltd
Priority date: 2018-01-24
Filing date: 2018-03-22
Publication date: 2020-08-21
Anticipated expiration: 2038-03-22
Also published as: CN108275846A

Abstract

A method for treating anthraquinone wastewater containing low-concentration nitrite comprises the following steps: (1) adjusting the pH value of the wastewater to acidity; (2) adding active ingredients, and stirring for 0.5-1 h; (3) inputting the mixture into a high-pressure reaction kettle, introducing air or oxygen, and carrying out oxidation reaction for 1-5 hours at a proper temperature; (4) performing solid-liquid separation on effluent, performing biochemical treatment on the liquid, wherein the solid is submicron ferric oxide, the content of nitrite in the anthraquinone wastewater is 0.01-1 wt%, the content of total organic carbon is 2000-30000 mg/L, and the active ingredient is Fe²⁺Inorganic/organic salts of (a). The treatment method can remove the nitrite and the total organic carbon in the wastewater simultaneously, has simple operation and low operation cost, is suitable for industrial application and is environment-friendly.

Description

Anthraquinone wastewater treatment method

Technical Field

The invention relates to a water pollution control and wastewater treatment technology, in particular to a treatment method of anthraquinone wastewater.

Background

Anthraquinone and its derivatives are important intermediates in the synthesis of dyes and medicines. At present, the annual output of the anthraquinone dye intermediate in China only exceeds 6 ten thousand tons, and wastewater with high chromaticity, high Chemical Oxygen Demand (COD) and high salinity can be discharged in the production process. Because the anthraquinone and the derivatives thereof have stable structures and high solubility, the treatment effect of the conventional physical and chemical method is not ideal.

Taking the production process of 1-nitroanthraquinone-5-sodium sulfonate as an example, the synthetic route is as follows:

according to the synthetic route, the 1-nitroanthraquinone-5-sodium sulfonate production wastewater contains residual raw materials, products, byproducts and sodium nitrite.

Because the removal difficulty of nitrate in water is far greater than that of nitrite, the existing sewage treatment method is generally carried out in two steps: nitrite is removed beforehand before the organic matter is degraded by oxidation. The commonly used reagents comprise reducing substances such as sulfamic acid, urea, ammonium salt, metal powder and the like, wherein reducing agents such as sulfamic acid, urea and the like are usually adopted in the treatment of high-concentration nitrite wastewater due to mild reaction conditions, no solid waste and the like. After nitrite removal, a subsequent oxidation means is used to remove total organic matter (TOC).

The CN103964634A Chinese patent document discloses a method for treating industrial wastewater with high nitrite, high carbonate and high COD concentration, firstly, sulfamic acid is used to remove nitrite, and then the COD of the wastewater is removed by the processes of precipitation, microelectrolysis, Fenton oxidation, microelectrolysis and flocculation. The method has high cost, large solid waste amount and difficult competitive advantage. The chinese patent document CN105130062A discloses a wet oxidation treatment method for anthraquinone wastewater. In an embodiment thereof, the nitrite at a high concentration (16% mass concentration) is removed by electrodialysis prior to wet oxidation; or after wet oxidation, the nitrate is converted into nitrate and then removed through concentrated crystallization. The two modes are only suitable for treating anthraquinone wastewater containing high-concentration nitrite, and the operation cost is high whether electrodialysis or concentration crystallization is adopted.

Disclosure of Invention

The invention provides a method for treating wastewater from nitroanthraquinone intermediate production, in particular to a method for synergistically improving the removal rate of low-concentration nitrite and total organic carbon in wastewater by adding active ingredients.

The wastewater treatment method of the invention comprises the following steps: (1) adjusting the pH value of the wastewater to acidity; (2) adding active ingredients, and stirring for 0.5-1 h; (3) inputting the mixture into a high-pressure reaction kettle, introducing air or oxygen, and performing a downward oxidation reaction at a proper temperature for 1-5 hours; (4) performing solid-liquid separation on the effluent, performing biochemical treatment on the liquid, wherein the solid is submicron ferric oxide, and the content of nitrite in the anthraquinone wastewater is0.01-1 wt%, and the content of Total Organic Carbon (TOC) is as follows: 2000-30000 mg/L, the active ingredient is Fe²⁺Inorganic/organic salts of (a).

Preferably, the molar ratio of the added active ingredients to nitrite in the wastewater is 1: 1-10.

In the method, the pH value of the wastewater is adjusted to be acidic, so that Fe is ensured²⁺No precipitation is caused.

The active ingredient of the invention is Fe²⁺Inorganic/organic salts of (A) containing only Fe²⁺A metal ion, which does not contain other metals such as copper or metal ions.

The method of the invention does not need to add hydrogen peroxide.

Preferably, Fe of the present invention²⁺The inorganic/organic salts are ferrous sulfate, ferrous chloride and ferrous gluconate; further preferred is ferrous sulfate.

Preferably, the anthraquinone waste water of the present invention is nitroanthraquinone waste water, for example, waste water from the production of nitroanthraquinone intermediates, and more preferably waste water from the production of nitroanthraquinone sulfonic acid intermediates.

Preferably, the temperature in the step (3) is 220-260 ℃.

Preferably, the removal rate of nitrite in the wastewater treated by the method is more than 80%, and the removal rate of TOC is more than 90%.

Preferably, the submicron ferric oxide obtained in the step (4) can be recycled after being rinsed.

Fe³⁺Specific to Fe²⁺The catalyst is stable, and the general catalyst needs to have certain stability. The present application has surprisingly found that the addition of Fe to waste water²⁺Even if Fe²⁺The addition amount of the compound is far lower than the theoretical molar amount required for removing the nitrite, and the nitrite and the TOC of the waste water generated in the production of the nitroanthraquinone intermediate can be simultaneously reduced to the level suitable for subsequent treatment at a proper temperature.

The nitrate content and TOC in the water obtained by the wastewater treatment method are both extremely low, and the wastewater basically does not contain nitrite, and can be subjected to solid-liquid separation. The liquid can be diluted according to the salt content of the effluent, and enters a biochemical pool for aerobic digestion treatment after being diluted until the effluent reaches the standard and is discharged. Bacteria tolerant to salt concentrations of 2% to 5% are preferably biochemically treated to reduce the dilution factor of the effluent. The solid is submicron ferric oxide, which can be used as ferric oxide red pigment and other raw materials for resource utilization after separation and rinsing, and the rinsing water is used as the next step biochemical dilution water.

Compared with the prior art, the method for treating the waste water from the production of the nitroanthraquinone intermediate can simultaneously remove nitrite and TOC in the waste water; the method has the characteristics of simple operation, short flow, strong repeatability among batches, stable effect, low operation cost and the like; solid waste and waste water are not additionally generated in the whole process, and the method is environment-friendly.

Detailed Description

The following examples are presented to aid in further understanding of the invention, and are not intended to limit the scope of the invention.

In the invention, the contents of nitrite and nitrate are measured by ion chromatography, TOC is measured by a TOC measuring instrument, and the particle size is measured by a laser particle size distribution instrument.

Example 1

The waste water produced by the 1-nitro-5-sulfonic anthraquinone intermediate has purple black color, TOC 14215mg/L, pH 12 and c (NO)₂ ^-) 4157 mg/L. Most of the organic matters in the wastewater are isomers of 1-nitro-5-sulfonic anthraquinone.

(1) Slowly dripping concentrated sulfuric acid into the wastewater to adjust the pH value of the wastewater to 3.

(2) Ferrous sulfate heptahydrate is added into the wastewater, and the molar ratio of the added ferrous sulfate heptahydrate to the nitrite is 1: 5. After the addition, bubbles are generated. Stirring was turned on for 0.5 h.

(3) Inputting the mixture into a high-pressure reaction kettle, introducing oxygen, sealing and heating to 240 ℃, and continuously reacting for 2 hours to obtain the oxidation treatment liquid. Standing, collecting supernatant, and measuring TOC 1060mg/L, c (NO)₃ ^-) No nitrite was detected at 840 mg/L. The removal rate of nitrite is 85% (nitrate is converted into nitrite according to molecular weight during calculation), and the removal rate of TOC is 93%.

(4) The solid phase in the oxidation treatment liquid is red ferric oxide particles, and the average particle size of the red ferric oxide particles is 557nm and submicron grade after rinsing and drying.

(5) Oxidizing the supernatant of the treated solution, measuring the salt content to be 8.7%, diluting the supernatant by three times, performing biochemical treatment for 24 hours by using bacteria resistant to high salt concentration, and reducing the TOC to 126mg/L after the treatment.

Example 2

The nitrite content of the wastewater described in example 1 was raised to 1% by adding an appropriate amount of sodium nitrite. The amount of ferrous sulfate heptahydrate added was increased to a molar ratio of 1:2 to nitrite, and the other conditions were the same as in example 1. Standing the obtained oxidation treatment solution, collecting supernatant, and detecting to obtain extract containing TOC 1098mg/L, C (NO)₃ ^-) 1167 mg/L. The calculation revealed that the nitrite removal rate was 91% and the TOC removal rate was 92%.

Example 3

The waste water of example 1 was treated under the same conditions as in example 1 except that the amount of ferrous sulfate heptahydrate added was reduced to a molar ratio of 1:10 to nitrite. Standing the obtained oxidation treatment solution, collecting supernatant, and detecting to obtain extract with TOC (1490 mg/L) and C (NO)₃ ^-) 974 mg/L. The calculation revealed that the nitrite removal rate was 83% and the TOC removal rate was 90%.

Example 4

The waste water of example 1 was treated by adding ferrous sulfate heptahydrate in a molar ratio of 1:1 to nitrite, and the rest of the conditions were the same as in example 1. Standing the obtained oxidation treatment solution, collecting supernatant, and detecting to obtain extract with TOC of 994mg/L, c (NO)₃ ^-) 1130 mg/L. The calculation revealed that the nitrite removal rate was 80% and the TOC removal rate was 93%.

Comparative example 1

The wastewater described in example 1 was directly fed into a high-pressure reactor to perform oxidation reaction, and the conditions of the amount of oxygen, temperature, reaction time and the like were the same as those in example 1. After the reaction, a sample was taken and tested, TOC 1375mg/L, c (NO)₃ ^-) 3547 mg/L. The calculation shows that the nitrite removal rate is 15% and the TOC removal rate is 90%.

Comparative example 1 illustrates that the nitrite removal rate is very low without the addition of an active material.

Comparative example 2

The wastewater described in example 1 was treated as follows:

(1) adding proper amount of sulfamic acid, starting stirring, reacting for 0.5h, sampling and measuring c (NO)₂ ^-)＝735mg/L。

(2) The wastewater after the above treatment was introduced into a high-pressure reactor to carry out oxidation reaction, and the conditions of oxygen amount, temperature, reaction time and the like were the same as those in example 1. After the reaction, a sample was taken and tested, TOC 3015mg/L, c (NO)₃ ^-) 1300 mg/L. The calculation revealed that the nitrite removal rate was 77% and the TOC removal rate was 79%.

Comparative example 2 illustrates that the wastewater TOC removal rate decreases dramatically after the prior removal of nitrite.

Comparative example 3

The wastewater described in example 1 was treated by adding equal molar amount of copper sulfate pentahydrate instead of adding ferrous sulfate heptahydrate, and the rest conditions were the same as in example 1. Adjusting pH of the obtained oxidation treatment solution to 10, precipitating, removing copper, sampling, and detecting, wherein TOC is 758mg/L, and c (NO)₃ ^-) 3210 mg/L. The calculation revealed that the nitrite removal rate was 43% and the TOC removal rate was 95%.

Comparative example 4

The wastewater described in example 1 was treated by adding iron sulfate heptahydrate instead of iron sulfate nonahydrate in an equimolar amount, and the rest of the conditions were the same as those in example 1. The resulting oxidation-treated solution was left to stand, and the supernatant was collected and assayed to obtain TOC 1269mg/L, c (NO)₃ ^-) 1950 mg/L. The calculation revealed that the nitrite removal rate was 65% and the TOC removal rate was 91%.

The results of comparative examples 3 and 4 show that only Fe²⁺The removal rate of TOC and nitrite from the wastewater can be greatly improved at the same time, which is surprising.

Claims

1. A method for treating anthraquinone wastewater comprises the following steps: (1) adjusting the pH value of the wastewater to acidity; (2) adding active ingredients, and stirring for 0.5-1 h; (3) inputting the mixture into a high-pressure reaction kettle, introducing air or oxygen, and carrying out oxidation reaction for 1-5 hours at the temperature of 220-260 ℃; (4) the effluent is subjected to solid-liquid separation, the liquid enters biochemical treatment, the solid is submicron ferric oxide,

wherein, the content of nitrite in the anthraquinone wastewater is 0.01-1 wt%, and the content of total organic carbon is as follows: 2000 to 30000mg/L,

the active ingredient is Fe²⁺Inorganic/organic salts of (a);

the molar ratio of the added active ingredients to nitrite in the wastewater is 1: 1-10.

2. The method of claim 1, wherein the Fe²⁺The inorganic/organic salts are ferrous sulfate, ferrous chloride or ferrous gluconate.

3. The method of claim 2, wherein the Fe²⁺The inorganic/organic salt of (a) is ferrous sulfate.

4. The method according to claim 1, wherein the anthraquinone waste water is nitroanthraquinone type waste water.

5. The method according to claim 1, wherein the anthraquinone waste water is a production waste water for producing nitroanthraquinone intermediates.

6. The method according to claim 1, wherein the anthraquinone waste water is a waste water from the production of nitroanthraquinone sulfonic acid-based intermediates.

7. The method according to claim 1, wherein the nitrite removal rate in the effluent of step (3) is above 80% and the TOC removal rate is above 90%.

8. The method according to claim 1, wherein the submicron ferric oxide obtained in step (4) can be recycled after rinsing.