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Advanced denitrification process and system for caprolactam production wastewater

A technology for production wastewater and deep denitrification, applied in biological water/sewage treatment, aerobic and anaerobic process treatment, water pollutants, etc., can solve problems such as failure to effectively reduce TN, high investment, high operating costs, and high COD , to achieve the effects of being conducive to commercial operation, increasing the TN removal rate, and reducing the cost of upgrading and transformation

Inactive Publication Date: 2022-05-27
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Chinese invention patent CN201110119504.1 discloses a membrane treatment process for caprolactam wastewater, and CN201410286565.0 discloses a method and device for treating caprolactam wastewater using membrane technology. Although better wastewater treatment effects can be obtained, the membrane process High operation and maintenance costs, not suitable for direct treatment of large volumes of wastewater
Invention patent ZL201110232634.6 discloses a treatment method and treatment device for wastewater containing caprolactam, through pre-aeration, coagulation sedimentation, anaerobic, aerobic, secondary coagulation sedimentation, ultrasonic disinfection, etc., the method embodiment Middle, NH 3 -N removal rate is only 91.8%, it is difficult to reduce TN below 30mg / L
Invention patent ZL201410811338.5 discloses a method of treating caprolactam wastewater by salting-out method, through salting-out and flocculation to precipitate part of the organic matter in the wastewater, and then biochemically and incinerate the reacted wastewater and sediment respectively. The investment and operating costs are high, and it is difficult to implement for large-volume wastewater
Invention patent CN201510868816.0 discloses a caprolactam wastewater advanced treatment process and device. This method treats the biochemically treated wastewater through acid adjustment, Fenton-like oxidation, pH adjustment precipitation, and coagulation precipitation. The purpose is to further reduce COD, color degree and total phosphorus, the removal effect on TN is limited
[0005] In summary, the existing caprolactam wastewater treatment technologies are mainly for the pretreatment of high-concentration wastewater such as oximation and hydrogen peroxide, which are difficult to biochemically degrade, the concentrated recovery of caprolactam, and the advanced treatment after A / O for reuse. These technologies mainly solve the problem of effluent NH 3 -N, high COD problem, failed to effectively reduce TN

Method used

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  • Advanced denitrification process and system for caprolactam production wastewater
  • Advanced denitrification process and system for caprolactam production wastewater
  • Advanced denitrification process and system for caprolactam production wastewater

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Example 1: Intermittent Demonstration Experiment

[0048] The experiment is divided into two groups, A and B, which are carried out in 2L beakers respectively. The wastewater to be treated is the effluent of the aerobic tank of the first-level A / O treatment process of a caprolactam production enterprise. The COD is about 110mg / L, and the TN is about 90mg. / L. The sludge is the acclimated return sludge of the middle settling tank, and the sludge concentration is 3.78g / L. Group A was directly sealed with plastic wrap at the mouth of the beaker, and the mixture in the beaker was magnetically stirred to simulate denitrification in the secondary hypoxia tank; in group B, methanol (247 mg / L) was added, and then the beaker was sealed with plastic wrap, and the mixed solution in the beaker was added. By magnetic stirring, denitrification in a secondary anoxic tank was simulated. The TN and NO of the two groups of mixed solutions were detected at the 12th, 18th, and 24th hours...

Embodiment 3

[0050] Example 3: Pilot test of secondary A / O series process (adding carbon source)

[0051] The design flow of the pilot plant is 1m 3 / h, consists of 1 hydrolysis acidification tank, 2 anoxic tanks, 2 aerobic tanks, 1 sedimentation tank and corresponding equipment such as aeration, stirring, and online dissolved oxygen meter. The tank body is made of Q235A anti-corrosion material. Sludge backflow is controlled by time relay, and the fan enters aeration volume through frequency conversion control to control dissolved oxygen within a certain range. The dosing of carbon source and lye is realized by two diaphragm pumps with a flow rate of 0-25L / h. The pump head of the diaphragm pump for dosing methanol is made of PP material, and the suction pipe is made of stainless steel to prevent methanol corrosion. The inlet water and nitrification liquid return pipes are equipped with rotameters to adjust the inlet water flow.

[0052] The influent water comes from a homogenization tank...

Embodiment 4

[0059] Example 4: Pilot test of secondary A / O series process (adding carbon source)

[0060] The design flow of the pilot plant is 1m 3 / h, consists of 1 hydrolysis acidification tank, 2 anoxic tanks, 2 aerobic tanks, 1 sedimentation tank and corresponding equipment such as aeration, stirring, and online dissolved oxygen meter. The tank body is made of Q235A anti-corrosion material. Sludge backflow is controlled by time relay, and the fan enters aeration volume through frequency conversion control to control dissolved oxygen within a certain range. The dosing of carbon source and lye is realized by two diaphragm pumps with a flow rate of 0-25L / h. The pump head of the diaphragm pump for dosing methanol is made of PP material, and the suction pipe is made of stainless steel to prevent methanol corrosion. The inlet water and nitrification liquid return pipes are equipped with rotameters to adjust the inlet water flow.

[0061] The influent water comes from the homogenization ta...

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Abstract

The invention provides a deep denitrification process and system for caprolactam production wastewater, and the main process flow is as follows: the caprolactam production wastewater is subjected to pretreatment such as oil separation and steam stripping, then is uniformly mixed and subjected to hydrolytic acidification, and then sequentially enters a first-stage anoxic tank, a first-stage aerobic tank, a second-stage anoxic tank and a second-stage aerobic tank; a certain amount of organic carbon source is added into the second-stage anoxic tank, one part of effluent of the second-stage aerobic tank flows back to the first-stage anoxic tank, and the other part of effluent of the second-stage aerobic tank enters a reclaimed water reuse treatment process after being settled. After the two-stage A / O series process is combined with the carbon source feeding treatment, the TN of the effluent can be reduced from 200-400 mg / L of the influent water to 15 mg / L or below. The method provided by the invention is suitable for upgrading and reconstruction of caprolactam production wastewater denitrification with an A / O biochemical treatment process as a core, and can realize deep denitrification of caprolactam wastewater on the premise of not increasing biochemical treatment retention time.

Description

technical field [0001] The invention relates to the technical field of sewage treatment, in particular to a deep denitrification process and system for caprolactam production wastewater. Background technique [0002] Caprolactam is an important organic chemical raw material. The polyamide obtained after polymerization can be processed into nylon fibers, engineering plastics and film materials, which are widely used in textile, electrical, mechanical and other fields. In 2019, the world's annual production capacity of caprolactam was 8.119 million tons, and my country accounted for more than 50%, reaching 4.19 million tons. The production process of caprolactam can be divided into toluene method, phenol method and benzene method according to the raw materials used, and the benzene method is dominant. According to the different production methods of cyclohexanone, benzene method can be divided into cyclohexane oxidation method and cyclohexene hydration method according to the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F3/30C02F9/14C02F103/36C02F101/38
CPCC02F3/302C02F9/00C02F2001/007C02F1/40C02F1/048C02F1/722C02F2305/026C02F2103/36C02F2101/38C02F2203/006C02F2301/046C02F2209/06C02F2209/22C02F2209/44C02F2209/16C02F2301/08Y02W10/10
Inventor 周仰原赵建夫姚国栋李雪珺
Owner TONGJI UNIV