CN-121974489-A - System and process for biochemical treatment of semi-coke wastewater by double carbon sources

CN121974489ACN 121974489 ACN121974489 ACN 121974489ACN-121974489-A

Abstract

The invention relates to a semi-coke wastewater double-carbon source biochemical treatment system and process, comprising the following steps that pretreated semi-coke wastewater enters a pre-anoxic tank for denitrification reaction to remove COD and total nitrogen; the effluent of the front anoxic tank enters an aerobic tank for carbonization and nitration reaction to remove organic matters and convert ammonia nitrogen into nitrite nitrogen and nitrate nitrogen, the effluent of the aerobic tank enters a rear anoxic pretreatment tank for endogenous denitrification reaction, mixed liquid in the rear anoxic pretreatment tank flows back to the front anoxic tank with a reflux ratio of 400% -800%, and the effluent of the rear anoxic pretreatment tank is subjected to mud-water separation and post treatment to reach the standard for reuse. The invention carries out mixed liquid reflux at the tail end of the post-anoxic pretreatment tank, has the characteristics of toxicity resistance, impact resistance, simple process flow and low operation cost, and simultaneously adopts a large reflux ratio to remove nitrate nitrogen and reduce the impact of biotoxicity on a biochemical system and the inhibition of microorganisms.

Inventors

CHEN LINA
LI FANG
GAO ZHIRONG
WU CHAOYANG
YANG YUQI
FENG CHI
CHEN TAO

Assignees

中冶南方都市环保工程技术股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260114

Claims (10)

1. The double-carbon source biochemical treatment process of the semi-coke wastewater is characterized by comprising the following steps of: S1, pre-treated semi-coke wastewater enters a pre-anoxic tank for denitrification reaction, and COD and total nitrogen are removed; S2, enabling the effluent of the front anoxic tank to enter an aerobic tank for carbonization and nitration, removing organic matters, and converting ammonia nitrogen into nitrite nitrogen and nitrate nitrogen; S3, enabling the effluent of the aerobic tank to enter a post-anoxic pretreatment tank for endogenous denitrification reaction, and enabling mixed liquid in the post-anoxic pretreatment tank to flow back to the pre-anoxic tank, wherein the backflow ratio is 400% -800%; S4, effluent of the post-anoxic pretreatment tank is subjected to mud-water separation and post-treatment to reach the standard for reuse.
2. The process for biochemical treatment of semi-coke wastewater with double carbon sources according to claim 1, wherein in step S1, the pretreatment comprises degreasing, deacidification and deamination and evaporation dephenolization.
3. The semi-coke wastewater double-carbon source biochemical treatment process according to claim 1, wherein in the step S1, the dissolved oxygen of the pre-anoxic tank is 0.1-0.5 mg/L, the sludge concentration is 4-8 mg/L, and the hydraulic retention time is 8-25 h.
4. The semi-coke wastewater double-carbon source biochemical treatment process according to claim 1, wherein in the step S2, the dissolved oxygen of the aerobic tank is 2-5 mg/L, the sludge concentration is 3-5 mg/L, and the hydraulic retention time is 40-65 h.
5. The process for biochemical treatment of semi-coke wastewater with double carbon sources according to claim 1, wherein in the step S3, the dissolved oxygen of the post-anoxic pretreatment tank is 0.1-0.5 mg/L, the sludge concentration is 3-5 mg/L, and the hydraulic retention time is 6-12 h.
6. The biochemical treatment process of the dual carbon source for the semi-coke wastewater according to claim 1, wherein in the step S3, the mixed solution in the post-anoxic pretreatment tank is refluxed after being stirred.
7. The biochemical treatment process of the semi-coke wastewater with double carbon sources according to claim 1, wherein in the step S4, the sludge obtained by the sludge-water separation is returned to the pre-anoxic tank.
8. A semi-coke wastewater double-carbon source biochemical treatment system for use in the process according to any one of claims 1-7, comprising a pretreatment unit, a pre-anoxic tank, an aerobic tank, a post-anoxic pretreatment tank, a secondary sedimentation tank and a post-treatment tank, wherein, The pretreatment unit is used for pretreating the semi-coke wastewater and uniformly stirring the semi-coke wastewater; The pre-anoxic tank is used for carrying out denitrification treatment on the pretreated semi-coke wastewater to remove COD and total nitrogen; The aerobic tank is used for carbonizing and nitrifying the effluent of the front anoxic tank, removing organic matters, and converting ammonia nitrogen into nitrite nitrogen and nitrate nitrogen; The post-anoxic pretreatment tank is used for carrying out endogenous denitrification treatment on the effluent of the aerobic tank and is connected with a water inlet area of the pre-anoxic tank through a mixed liquid reflux pump; the secondary sedimentation tank is used for separating mud from water in the effluent of the post-anoxic pretreatment tank; the post-treatment tank is used for carrying out post-treatment on effluent of the secondary sedimentation tank to achieve the standard and recycle.
9. The biochemical treatment system of the dual carbon sources for the semi-coke wastewater, according to claim 8, is characterized in that a submerged stirring device is arranged in each of the front anoxic tank and the rear anoxic pretreatment tank, and an aeration system is arranged in the aerobic tank.
10. The semi-coke wastewater double-carbon source biochemical treatment system according to claim 8, wherein the secondary sedimentation tank is connected with a water inlet area of the front anoxic tank through a sludge reflux pump.

Description

System and process for biochemical treatment of semi-coke wastewater by double carbon sources Technical Field The invention relates to the field of wastewater treatment, in particular to a semi-coke wastewater double-carbon source biochemical treatment system and a semi-coke wastewater double-carbon source biochemical treatment process. Background The semi-coke wastewater is wastewater generated in semi-coke production and gas purification processes, and mainly comes from raw gas circulating condensate, gas purification wastewater and the like. The semi-coke wastewater has complex water quality and contains a large amount of coal tar, phenols, ammonia nitrogen, sulfides, cyanides and other pollutants. Wherein CODcr is up to 20000-90000 mg/L, helium nitrogen is 3000-7000 mg/L, total phenol is 10000-15000 mg/L, and petroleum is 1000-5000 mg/L. The semi-coke wastewater treatment process is long in flow and numerous in influencing factors, no mature full-flow semi-coke wastewater treatment technology exists at home and abroad at present, the treatment method mainly uses the coking wastewater treatment technology with similar water quality, a semi-coke oven usually adopts energy-saving and environment-friendly coke quenching modes such as steam, dry method and the like, but the mode of using the semi-coke wastewater treatment for coke quenching after reaching standards has environmental protection risks, and the semi-coke wastewater treatment needs to realize zero wastewater discharge. The conventional treatment process for zero emission of semi-coke wastewater in China mainly comprises a pretreatment section, a biochemical treatment section, an advanced treatment section, a recycling treatment section and an evaporation crystallization section, wherein the conventional pretreatment section mainly comprises oil removal, deacidification, deamination and evaporation dephenolization, but the semi-coke wastewater is subjected to oil removal, deacidification, deamination, evaporation concentration and other processes, the obtained evaporation condensate still contains a large amount of volatile phenol, a small amount of oil and ammonia nitrogen, CODcr is as high as 2000mg/L-3500mg/L, the CODcr directly enters a membrane system for treatment and is very easy to cause membrane fouling and blockage, frequent cleaning and regeneration are required, the service life of a membrane product is influenced, or even the membrane system is difficult to normally operate, in addition, ammonia nitrogen also can cause the problem that the membrane produced water is not up to standard, meanwhile, phenol-containing wastewater has biotoxicity, free ammonia has remarkable biological inhibition effect, and is easy to be impacted easily by adopting a conventional biochemical treatment process. Therefore, the adoption of the evaporation dephenolization pretreatment process faces the difficult problem of removing pollutants in evaporation condensate and even realizing zero emission of wastewater. Disclosure of Invention The invention aims to overcome the technical defects, and provides a double-carbon source biochemical treatment system and a double-carbon source biochemical treatment process for semi-coke wastewater, which solve the technical problems that pollutants in evaporation condensate are difficult to remove and the treatment is difficult due to stronger biotoxicity and biological inhibition effect by adopting an evaporation dephenolization pretreatment process in the prior art. In order to achieve the technical purpose, the technical scheme provided by the invention is as follows: The invention provides a double-carbon source biochemical treatment process of semi-coke wastewater, which comprises the following steps of S1, enabling pretreated semi-coke wastewater to enter a front anoxic tank for denitrification reaction to remove COD and total nitrogen, S2, enabling effluent of the front anoxic tank to enter an aerobic tank for carbonization and nitration reaction to remove organic matters and convert ammonia nitrogen into nitrite nitrogen and nitrate nitrogen, S3, enabling effluent of the aerobic tank to enter a rear anoxic pretreatment tank for endogenous denitrification reaction, enabling mixed liquor in the rear anoxic pretreatment tank to flow back to the front anoxic tank, enabling the backflow ratio to be 400% -800%, and S4, enabling effluent of the rear anoxic pretreatment tank to reach the standard for recycling through mud-water separation and post treatment. The invention provides a two-carbon source biochemical treatment system for semi-coke wastewater, which comprises a pretreatment unit, a pre-anoxic tank, an aerobic tank, a post-anoxic pretreatment tank, a secondary sedimentation tank and a post-treatment tank, wherein the pretreatment unit is used for pretreating and uniformly stirring the semi-coke wastewater, the pre-anoxic tank is used for denitrifying the pretreated semi-coke wastewater to remove COD and total n