CN111039511A

CN111039511A - Modularized integrated process method for treating chemical recovered wastewater

Info

Publication number: CN111039511A
Application number: CN201911392486.7A
Authority: CN
Inventors: 何亚婷
Original assignee: Individual
Current assignee: Shenzhen Ruiweisheng Environmental Protection Technology Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-04-21
Anticipated expiration: 2039-12-30
Also published as: CN111039511B

Abstract

The invention belongs to the technical field of environmental management and resource utilization, and particularly relates to a modular integrated process method for treating chemical recovered wastewater, which is characterized by comprising the following steps of: aiming at the problem that organic wastewater generated in the production process of the polyester industry is more difficult to treat by high-concentration wastewater discharged after being treated by an acetaldehyde recovery technology, process integration and parameter design are carried out, and the integrated process consists of 3 modules: the system comprises a primary pretreatment module, a secondary biochemical module and a tertiary advanced treatment module, wherein the primary pretreatment module is mainly provided with an adjusting and acid adjusting tank, an improved Fenton reactor, an electrochemical reactor, a sedimentation tank and a neutralization tank; the secondary biochemical module is mainly provided with an anaerobic submodule (an internal and external dual-reinforced circulation anaerobic reactor) and an aerobic submodule (a biological contact oxidation tank and a membrane bioreactor); the three-level advanced treatment module is mainly provided with a heterogeneous catalysis ozone activated carbon adsorption reactor. The process has the characteristics of flexibility, high efficiency, convenience, intelligence and the like, and can ensure economic, effective and stable operation of wastewater treatment facilities.

Description

Modularized integrated process method for treating chemical recovered wastewater

Technical Field

The invention belongs to the technical field of environmental management and resource utilization, and particularly relates to a high-concentration esterification wastewater treatment system treated by adopting an acetaldehyde recovery technology, which aims at solving the problem that organic wastewater generated in the production process of the polyester industry is more difficult to treat high-concentration wastewater discharged after being treated by the acetaldehyde recovery technology, carries out process integration and parametric design, and realizes process modularization, intellectualization and integration.

Background

In recent years, under the influence of vigorous cultivation of national policies and rapid development of economic levels, the chemical industry develops rapidly, wherein the yield of the polyester industry is greatly increased, more and more esterification wastewater is generated in the process, and great threat is caused to the ecological environment and daily life.

The esterification wastewater, namely wastewater discharged in polyester production, is mostly from esterification reaction, concentrated sulfuric acid is used as a catalyst for accelerating the reaction in the polyester production process, so that the polyester wastewater has strong acidity and pH of about 2-3, and substances such as benzene ring polymers, diethylene glycol, acetaldehyde, ethylene glycol, 2-methyl-1, oxalic acid and the like contained in the wastewater cause the esterification wastewater to have complex components and poor biochemical property, high COD (chemical oxygen demand), low N, P content and great treatment difficulty, and partial substances containing the benzene ring structures are difficult to biodegrade. Such waste water has high stability, corrosiveness, irritation and toxicity, and if the waste water is directly discharged without being treated, the waste water poses great threats to the environment and human health. The traditional treatment method of the esterification wastewater is to burn organic matters after steam stripping, so as to recover heat and save part of fuel. However, acetaldehyde and ethylene glycol white, which have high added values, are burned off unfortunately, and incineration is often insufficient, and the environment is polluted. Acetaldehyde is an important chemical intermediate, has high market value, and is widely applied to producing products with higher values such as pentaerythritol, pyridine and the like. Ethylene glycol is one of the main synthetic raw materials of polyester production enterprises, and the demand is large. Therefore, the recovery of acetaldehyde and ethylene glycol from the esterification wastewater is a demand of more polyester enterprises. By adopting an acetaldehyde recycling technology, on one hand, the COD value of the esterification wastewater can be reduced, and the environmental protection level of enterprises is improved; on the other hand, the recovery of acetaldehyde can save energy consumption and bring good economic benefits to enterprises. However, the concentration of the discharged wastewater dye is still high after the acetaldehyde recycling technology is adopted, partial substances containing benzene ring structures and other complex long-chain pollutants have poor biochemical performance and high toxicity, COD is about 1000-5000 mg/L, BOD is only 10-50 mg/L, and the N, P content is respectively lower than 50mg/L and 5 mg/L.

The present invention is therefore directed to the problem of:

① esterification wastewater has complex components and poor biochemical property, high COD, low N, P content and great treatment difficulty, and partial substances containing a benzene ring structure and some long-chain complex organic matters are difficult to biodegrade;

② in the preparation process of polyester products, the changes of production raw materials and production lines, machine maintenance and production faults all affect the composition, discharge amount and discharge concentration of esterification wastewater, COD index can fluctuate greatly, the fluctuation is reflected on the discharged esterification wastewater treated by adopting acetaldehyde recycling technology, and the change of pollutant concentration has adverse effect on the subsequent biochemical treatment;

③ the national discharge standard of waste water is more and more strict, and the requirement of reuse water is also higher, and the esterified waste water is difficult to be directly treated to the reuse water standard.

Along with the stricter and stricter requirements on domestic environmental protection, the requirements on daily water consumption and reuse water rate of industrial plants are higher and higher, so that the discharged wastewater must be recycled, and the esterification wastewater treatment urgently needs a sewage treatment technology which has good treatment effect, simple and convenient operation, small occupied area and low investment and can realize wastewater reuse.

Disclosure of Invention

The invention particularly relates to a modular integrated process method for treating chemical recovery wastewater, which is mainly suitable for high-concentration esterification wastewater generated after polyester industrial wastewater is treated by an acetaldehyde recovery technology, and is used for carrying out process integration and parametric design to realize process modularization, intellectualization and integration.

The invention relates to a modular integrated process method for treating chemical recovered wastewater, which comprises three stages of modules, namely a primary pretreatment module, a secondary biochemical module and a tertiary advanced treatment module.

The primary pretreatment module is provided with an adjusting and acid adjusting tank, an improved Fenton reactor, an electrochemical reactor, a sedimentation tank and a neutralization tank; the adjusting and acid-regulating tank inlet is connected with an outlet of a polyester industrial wastewater acetaldehyde recovery processing system, the adjusting and acid-regulating tank outlet is connected with an inlet of an improved Fenton reactor, an outlet of the improved Fenton reactor is connected with an inlet of an electrochemical reactor, an outlet of the electrochemical reactor is connected with an inlet of a sedimentation tank and an inlet of an adjusting and acid-regulating tank, an outlet of the sedimentation tank is connected with an inlet of a neutralization tank, and the outlet of the neutralization tank enters a secondary biochemical module.

The secondary biochemical module is provided with an anaerobic submodule and an aerobic submodule; the anaerobic submodule is an internal and external dual-reinforced circulation anaerobic reactor; the aerobic submodule comprises a biological contact oxidation pond and a membrane bioreactor; the anaerobic submodule and the aerobic submodule are arranged in series; the inlet of the internal and external double reinforced circulation anaerobic reactor is connected with the outlet of the neutralization tank, the outlet of the internal and external double reinforced circulation anaerobic reactor is connected with the inlet of the biological contact oxidation tank, the outlet of the biological contact oxidation tank is connected with the inlet of the membrane bioreactor, and the effluent of the membrane bioreactor enters the third-stage advanced treatment module.

The three-stage advanced treatment module is provided with a heterogeneous catalysis ozone activated carbon adsorption reactor; the inlet of the heterogeneous catalysis ozone activated carbon adsorption reactor is connected with the outlet of the membrane bioreactor, and the outlet of the heterogeneous catalysis ozone activated carbon adsorption reactor is connected with the total discharge port.

The connection between the cell bodies is pipeline and valve connection, the pipeline is the anticorrosive pipe of plastics or anticorrosive pipe of metal, the valve is solenoid valve, can realize automatic control through PLC.

The volume retention time is adjusted to the design of adjusting the acid adjusting tank and is 8-12 h, the tank body adopts a concrete tank lining anticorrosive material or a glass fiber reinforced plastic anticorrosive tank, air stirring is adopted, and the stirring intensity is 0.3-0.5 m³Air/(min. m)²Pool surface area), adjusting acid by using waste stock solution or concentrated sulfuric acid, and arranging a lifting water pump in the pool.

The modified Fenton reactor is fluidizedThe bed is in a form of a bed, a special-shaped guide wall is arranged in the bed, the special-shaped guide wall is in an inverted cone shape, the ascending flow speed of the system design is 1.5-2 m/s, the reaction pH is 3-4, ferrous sulfate and hydrogen peroxide are added, the dosage is that 2-3 mg/L ferrous sulfate and 1-1.5 mg/LH are added according to the condition that 1mg/LCOD is removed₂O₂。

The electrochemical reactor is in a fluidized bed form, bottom aeration is adopted for mixing and increasing the ascending flow velocity, and the aeration parameter is designed to be 0.8-1 m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode to enhance the corrosion resistance of the anode, and the titanium plate is used as a cathode, and the installed capacity is 1-1.5W/(m)³Water/h).

The sedimentation tank is a vertical flow sedimentation tank, the designed ascending flow velocity is 0.1-0.2 mm/s, Polyacrylamide (PAM) is added to serve as a flocculating agent, a tubular mixer is arranged on a water inlet pipe of the sedimentation tank, and the designed medicament adding amount is 2-3 mg/L.

And the mixing reaction time of the neutralization tank is designed to be 0.5-1 h, waste alkali liquor or sodium hydroxide is added as a neutralizing agent, and the pH value of the added wastewater is 7-8.

The operation method of the primary pretreatment module is an intermittent multi-stage circulating reaction according to BOD of inlet water organic matters₅The COD value designs three sets of operation modes, adopts first grade circulation, second grade circulation and tertiary circulation respectively, and specific operation mode is:

when raw water BOD₅When COD is more than 0.4, the flow sequence of the wastewater is as follows: water → adjusting and adjusting acid pool → modified Fenton reactor → electrochemical reactor → sedimentation tank → neutralization pool → effluent; the total reaction time of the system is 3.0-3.9 h, wherein the acid regulating pool is adjusted to run for 0.5h, the improved Fenton reactor runs for 0.3-0.5 h, the electrochemical reactor runs for 0.1-0.2 h, the sedimentation pool runs for 1.5h, and the neutralization pool runs for 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and acid adjusting tank, 40% of the improved Fenton reactor, 50% of the electrochemical reactor, 10% of the sedimentation tank and 0% of the neutralization tank;

when the raw water is less than or equal to 0.2 BOD₅When COD is less than or equal to 0.4, the flow sequence of the wastewater is as follows: incoming water → pH adjusting pool → modified Fenton reactor → electrochemical reactor → pH adjusting pool → modified Fenton reactionVessel → sedimentation tank → neutralization tank → effluent; the total reaction time of the system is 3.9-4.4 h, wherein the adjusting acid regulating pool runs for 0.5h, the improved Fenton reactor runs for 0.4-0.6 h, the electrochemical reactor runs for 0.1-0.2 h, the adjusting acid regulating pool runs for 0.5h, the improved Fenton reactor runs for 0.4-0.6 h, the sedimentation tank runs for 1.5h, and the neutralization tank runs for 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization tank;

when raw water BOD₅When COD is less than 0.2, the flow sequence of the wastewater is as follows: the coming water → the adjusting and acid adjusting pool → the improved Fenton reactor → the electrochemical reactor → the adjusting and acid adjusting pool → the improved Fenton reactor → the sedimentation tank → the neutralization pool → the yielding water; the total reaction time of the system is 4.9-5.7 h, wherein the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the electrochemical reactor is 0.1-0.2 h, the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the sedimentation pool is 1.5h and the neutralization pool is 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and acidity adjusting tank, 15% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and acidity adjusting tank, 15% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization tank.

The internal and external dual reinforced circulation anaerobic reactor is divided into a mixing zone, a 1 st anaerobic zone, a 2 nd anaerobic zone, a settling zone and a gas-liquid separation zone from bottom to top, wastewater flows in the reactor from bottom to top, an internal reinforced circulation and an external reinforced circulation system are added, and the flow of an internal and external circulation pump can be automatically controlled according to the water quality during operation;

the internal reinforced circulation is that the effluent of the 1 st anaerobic zone returns to the water inlet end, and the ratio a of the internal circulation flow to the water inlet flow is determined according to the formula (1):

the external forced circulation is that the effluent of the 2 nd anaerobic zone returns to the water inlet end, and the ratio b of the external circulation flow to the influent flow is determined according to the formula (2):

the total residence time of the biological contact oxidation tank is designed to be 30-40 h, the biological contact oxidation tank comprises an anoxic section and an aerobic section, the residence time of the aerobic section is more than 28h, and the volume load of filler COD is designed to be 0.01-0.02 kgCOD/(m)³·d)；

The membrane bioreactor is designed to have the sludge load of 0.01-0.02 BOD₅And (kgMLSS d), the designed retention time is 8-15 h, and the designed MLSS is 8000-10000 mg/L.

The heterogeneous catalysis ozone activated carbon adsorption reactor is designed to have the reaction time of 0.5h, a heterogeneous catalysis reaction layer is arranged at the bottom of the reactor, and an activated carbon layer is arranged at the upper part of the reactor; the heterogeneous catalytic reaction layer is a magnetic nano composite filler, the magnetic nano composite filler is prepared by taking nickel-zinc ferrite as a magnetic core and hydrolyzing tetraethyl silicate; the design height of the filler is 0.3-0.5 m; the activated carbon layer is made of granular activated carbon, the particle size is 2-5 mm, and the height of the activated carbon layer is 2-3 m.

The modularized integrated process method for treating the chemical recovered wastewater comprises the following steps of comparing and analyzing a real-time online water quality monitoring result of a water inlet end and a water outlet end of each module and each submodule with a reuse water standard, outputting the result to an automatic control system, sending a control signal to each module or each submodule unit by the automatic control system, and adjusting the operation mode and parameters of each module and each submodule, wherein the specific control method comprises the following steps:

1. when the concentration of SS (suspended solid) or total dissolved solids or volatile phenol in the effluent of the membrane bioreactor is greater than the standard limit value of reuse water, the effluent enters a heterogeneous catalytic ozone activated carbon adsorption reactor;

2. when the membrane bioreactor discharges water BOD₅Or when the COD concentration is greater than the standard limit value of the recycled water, the volume load of the biological contact oxidation pond is reduced, and the single adjustment amount is 5 gCOD/(m)³·d)；

3. When the concentration of ammonia nitrogen or total nitrogen in the effluent of the membrane bioreactor is greater than the standard limit value of reuse water, the yield of sludge is improved, and the single adjustment amount is 0.01 kgMLSS/kgCOD;

4. when the total phosphorus concentration of the effluent of the membrane bioreactor is greater than the standard limit value of the reuse water, reducing the ascending flow rate of the sedimentation tank, wherein the single adjustment amount is 0.05mm/s, and increasing the adding amount of Polyacrylamide (PAM), wherein the single adjustment amount is 0.2 mg/L;

5. when the total hardness or the total alkalinity of the effluent of the membrane bioreactor is greater than the standard limit value of the recycled water, the designed mixed reaction time of the neutralization pond is increased, and the single adjustment amount is 0.1 h;

6. when the concentration of iron or manganese in the inlet water of the electrochemical reactor is greater than the standard limit value of the recycled water, the installed capacity is reduced, and the single adjustment amount is 0.1W/(m)³Water/h);

the reuse water standard limit is shown in table 1:

TABLE 1 Standard Limit value of reuse Water

Item	Index (mg/L)	Item	Index (mg/L)
				SS	30	Chloride compound	300
BOD₅	10	Total hardness (as CaCO)₃Meter)	850
				COD	50	Total alkalinity (as CaCO)₃Meter)	500
Iron	0.3	Total dissolved solids	800
				Manganese oxide	0.2	Ammonia nitrogen	1
Total phosphorus	4	Petroleum products	0.5
				Volatile phenols	0.5	Total nitrogen	5

The invention relates to a modular integrated process method suitable for polyester industrial wastewater treatment, which has the following technical characteristics:

1. the system is suitable for treating high-concentration esterification wastewater which is generated after the treatment of the acetaldehyde recovery technology and has high concentration, complex components and large fluctuation, the process flexibility is particularly strong, and even if the treatment of the acetaldehyde recovery technology is stopped, the wastewater with high concentration and without recovery treatment can also be born when entering the system;

2. according to the characteristics of the wastewater treated by the high-concentration esterification wastewater generated after the treatment of the acetaldehyde recovery technology, a specially-strengthened pretreatment module, a targeted biochemical treatment module and a deep treatment module with strong guarantee are arranged, so that the process is advanced, the pertinence is strong, and the impact resistance is strong;

3. the process combination has high modularization degree, is beneficial to the technology to be converted into integrated equipment, and saves space;

4. the process combination technology is advanced, COD, nitrogen and phosphorus can be treated simultaneously, the stability reaches the standard, and the effluent can be recycled.

Drawings

FIG. 1 is a process scheme of the present invention.

FIG. 2 is a schematic diagram of the system control connection according to the present invention.

Wherein: 1. a primary pre-processing module; 2. a secondary biochemical module; 3. a third-level advanced processing module; 4. a computer automatic control system; 5. an online water quality monitoring system; a. adjusting an acid adjusting pool; b. modifying the Fenton reactor; c. an electrochemical reactor; d. a sedimentation tank; e, a neutralization pool; f, strengthening the circulation anaerobic reactor inside and outside; g. a biological contact oxidation pond; h. a membrane bioreactor; i. a heterogeneous catalysis ozone active carbon adsorption reactor;

→ process lines; a signal input/output.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are described in more detail, the described embodiments are a part of embodiments of the present invention, but not all embodiments, and the present invention is further described below with reference to the embodiments and the accompanying drawings.

As shown in figures 1 and 2, the invention particularly relates to a modular integrated process method for treating chemical recovery wastewater, which has the selection principle of ① technology maturity and reliability, ② operation stability, ③ maintenance and management convenience, ④ economy and applicability, and specifically selects a high-concentration esterification wastewater treatment process according to the characteristics of wastewater and the requirements of the wastewater treatment process.

Considering investment and operating cost, biochemical treatment is required, but a single anaerobic process and an aerobic process cannot realize high-concentration organic matter in the esterification wastewater to be efficiently removed, and the wastewater generated after the polyester industrial wastewater is treated by an acetaldehyde recovery technology has the characteristics of poorer biochemical property and higher toxicity, so the anaerobic process and the aerobic process are required to be operated in a combined manner, and an extremely effective pretreatment process is required to be arranged before biochemical treatment.

The invention relates to a modular integrated process method for treating chemical recovered wastewater, which comprises three stages of modules, namely a primary pretreatment module 1, a secondary biochemical module 2 and a tertiary advanced treatment module 3.

The primary pretreatment module is provided with an adjusting and acid adjusting tank a, an improved Fenton reactor b, an electrochemical reactor c, a sedimentation tank d and a neutralization tank e; the inlet of the adjusting and acid-adjusting tank a is connected with the outlet of a polyester industrial wastewater acetaldehyde recovery processing system, the outlet of the adjusting and acid-adjusting tank a is connected with the inlet of the improved Fenton reactor b, the outlet of the improved Fenton reactor b is connected with the inlet of the electrochemical reactor c, the outlet of the electrochemical reactor c is connected with the inlet of the sedimentation tank d and the inlet of the adjusting and acid-adjusting tank a, the outlet of the sedimentation tank d is connected with the inlet of the neutralization tank e, and the outlet of the neutralization tank e enters the secondary biochemical module 2.

The secondary biochemical module 2 is provided with an anaerobic submodule and an aerobic submodule; the anaerobic submodule is an internal and external dual-reinforced circulation anaerobic reactor f; the aerobic submodule comprises a biological contact oxidation pond g and a membrane bioreactor h; the anaerobic submodule and the aerobic submodule are arranged in series; the inlet f of the internal and external double reinforced circulation anaerobic reactor is connected with the outlet e of the neutralization tank, the outlet f of the internal and external double reinforced circulation anaerobic reactor is connected with the inlet g of the biological contact oxidation tank, the outlet g of the biological contact oxidation tank is connected with the inlet h of the membrane bioreactor, and the effluent of the membrane bioreactor enters the third-stage advanced treatment module 3.

The three-stage advanced treatment module 3 is provided with a heterogeneous catalysis ozone activated carbon adsorption reactor i; the inlet of the heterogeneous catalysis ozone activated carbon adsorption reactor i is connected with the outlet of the membrane bioreactor h, and the outlet of the heterogeneous catalysis ozone activated carbon adsorption reactor i is connected with the total discharge port.

Further, the volume retention time is adjusted to be 8-12 h by adjusting the design of the acid adjusting tank a, the tank body is made of a concrete tank lining anticorrosive material or a glass fiber reinforced plastic anticorrosive tank, air stirring is adopted, and the stirring strength is 0.3-0.5 m³Air/(min. m)²Pool surface area), adjusting acid by using waste stock solution or concentrated sulfuric acid, and arranging a lifting water pump in the pool.

The function of the acid regulating pool a is as follows:

(1) adjusting water quantity: the water quantity and the water quality of the wastewater discharged from industrial enterprises are changed along with time, the change amplitude of the industrial wastewater is generally larger than that of urban sewage, and the water quantity and the water quality of the wastewater need to be adjusted in order to ensure the normal operation of subsequent treatment structures or equipment;

(2) requirements for the operation of the pre-processing module: because the pretreatment module is used for intermittent treatment, continuous incoming water is temporarily stored in the adjusting and acid adjusting tank during pretreatment reaction;

(3) mixing: the effluent of the electrochemical reactor is mixed with the incoming water, so that the concentration of pollutants in the raw water is adjusted, and the concentration variation difference of the incoming water is reduced;

(4) acid adjustment: two purposes of acid regulation are provided, firstly, the pH of the incoming water, namely the esterification wastewater to be treated does not meet the requirement of subsequent treatment, and the incoming water is regulated; and secondly, the wastewater treated by the electrochemical reactor needs to return to an acid regulating and adjusting tank for repeated treatment according to the process characteristics, and when the pH value of the mixed effluent of the electrochemical reactor and the incoming water cannot meet the subsequent requirements, the effluent is subjected to acid regulation and then enters the improved Fenton reactor for reaction.

The improved Fenton reactor b is in a fluidized bed form, a special-shaped guide wall is arranged inside the improved Fenton reactor b, the special-shaped guide wall is in an inverted cone shape, and after the special-shaped guide wall is arranged, the Reynolds number of water flow of the system is increased, so that the waste water flow state is in a turbulent flow state, the mixing effect of a medicament and waste water is enhanced, the reaction time is greatly reduced, and the systemDesigning the rising flow rate to be 1.5-2 m/s, the reaction pH to be 3-4, adding ferrous sulfate and hydrogen peroxide, adding 2-3 mg/L ferrous according to the condition of removing 1mg/LCOD, and adding 1-1.5 mg/LH₂O₂。

The modified Fenton reactor b is particularly selected according to the characteristics of the esterification wastewater, the COD of the esterification wastewater is approximately between 10000 and 50000 and the pH is approximately 2 to 3 before the esterification wastewater is treated, and after the esterification wastewater is treated by an acetaldehyde recovery technology, the COD is approximately between 1000 and 5000 and the pH is approximately 3 to 4. Because the esterification wastewater contains diethylene glycol, acetaldehyde, ethylene glycol, 2-methyl-1 and oxalic acid, and the pH value of the wastewater is 2-4, the Fenton oxidation method is an efficient and economic advanced wastewater oxidation technology, hydrogen peroxide and ferrous ions react to generate hydroxyl radicals with strong oxidizing property, so that pollutants in the wastewater are oxidized and degraded, the oxidation effect on organic compounds such as polycarboxylic acid, alcohol and ester is extremely remarkable, and the treatment effect is better under an acidic condition. Therefore, the invention selects the improved Fenton reactor, firstly, part of complex organic pollutants which are easy to be chemically oxidized can be removed, the load of electrochemical reaction is reduced, and secondly, the water treatment cost of the acid regulating part can be reduced by directly utilizing the characteristics of raw water.

The electrochemical reactor c is in a fluidized bed form, bottom aeration is adopted for mixing and increasing the ascending flow velocity, and the aeration parameter is designed to be 0.8-1 m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode to enhance the corrosion resistance of the anode, and the titanium plate is used as a cathode, and the installed capacity is 1-1.5W/(m)³Water/h).

The sedimentation tank d is a vertical flow sedimentation tank, the designed ascending flow rate is 0.1-0.2 mm/s, Polyacrylamide (PAM) is added as a flocculating agent and directly added into a water inlet pipe of the sedimentation tank, and hydraulic mixing is carried out, wherein the designed adding amount is 2-3 mg/L.

And the neutralization tank e is designed to be mixed and reacted for 0.5-1 h, waste alkali liquor or sodium hydroxide is added as a neutralizing agent, and the pH value of the added wastewater is 7-8.

The operation method of the primary pretreatment module 1 is an intermittent multi-stage circulating reaction according to BOD of inlet water organic matters₅The COD value is designed into three sets of operation modes,the method adopts primary circulation, secondary circulation and tertiary circulation respectively, and the specific operation mode is as follows:

when the raw water is less than or equal to 0.2 BOD₅When COD is less than or equal to 0.4, the flow sequence of the wastewater is as follows: the coming water → the adjusting and acid adjusting pool → the improved Fenton reactor → the electrochemical reactor → the adjusting and acid adjusting pool → the improved Fenton reactor → the sedimentation tank → the neutralization pool → the yielding water; the total reaction time of the system is 3.9-4.4 h, wherein the adjusting acid regulating pool runs for 0.5h, the improved Fenton reactor runs for 0.4-0.6 h, the electrochemical reactor runs for 0.1-0.2 h, the adjusting acid regulating pool runs for 0.5h, the improved Fenton reactor runs for 0.4-0.6 h, the sedimentation tank runs for 1.5h, and the neutralization tank runs for 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization tank;

when raw water BOD₅When COD is less than 0.2, the flow sequence of the wastewater is as follows: the coming water → the adjusting and acid adjusting pool → the improved Fenton reactor → the electrochemical reactor → the adjusting and acid adjusting pool → the improved Fenton reactor → the sedimentation tank → the neutralization pool → the yielding water; the total reaction time of the system is 4.9-5.7 h, wherein the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the electrochemical reactor is 0.1-0.2 h, the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the sedimentation pool is 1.5h and the neutralization pool is 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting acid adjusting pool, 15% of the improved Fenton reactor and electrochemistry40% of a reactor, 0% of an adjusting and acid-regulating pool, 15% of an improved Fenton reactor, 40% of an electrochemical reactor, 0% of an adjusting and acid-regulating pool, 15% of an improved Fenton reactor, 10% of a sedimentation tank and 0% of a neutralization tank;

each unit of the primary pretreatment module 1 is selected in a targeted manner according to the characteristics of the esterification wastewater, the COD removal rate is the ratio of the water inlet index and the water outlet index of a single tank body, the reactor can automatically control the operation index of the reactor according to the COD index of the wastewater, and the specific expression is that the Fenton reactor is improved to realize the standard removal rate for controlling the dosage, and the electrochemical reactor realizes the standard removal rate by controlling the input power.

Because the esterification wastewater treated by the acetaldehyde recovery technology has organic matters with complex components, including organic matters containing benzene rings, such as aromatic compounds, long-chain organic pollutants, such as combined fibers and other organic pollutants, the operation mode of the improved Fenton reactor, namely the electrochemical reactor, the improved Fenton reactor, the electrochemical reactor and the improved Fenton reactor is adopted.

Because the requirement on the effluent is higher, the effluent index and the operation cost are considered, and a secondary biochemical module is arranged.

The internal and external double reinforced circulation anaerobic reactor f adopted in the invention is a new generation of high-efficiency anaerobic reactor, wastewater flows from bottom to top in the reactor, pollutants are adsorbed and degraded by bacteria, and purified water flows out from the upper part of the reactor; the reactor is divided into 5 zones from bottom to top according to the function division, namely a mixing zone, a 1 st anaerobic zone, a 2 nd anaerobic zone, a settling zone and a gas-liquid separation zone, and the reactor is characterized in that an external circulation system is added on the basis of an internal circulation anaerobic reactor, and the flow of an external circulation pump can be automatically controlled according to the water quality during operation so as to achieve smaller floor area and better treatment effect.

The internal reinforced circulation is that the water outlet of the first reaction chamber returns to the water inlet end, the relation between the internal circulation flow and the water inlet flow is shown in a formula, and the ratio of the internal circulation flow to the water inlet flow is a:

the external reinforced circulation is that the water outlet of the second reaction chamber returns to the water inlet end, the relation between the external circulation flow and the water inlet flow is shown in a formula, and the ratio b of the external circulation flow to the water inlet flow is as follows:

the total designed retention time of the biological contact oxidation pond g is 30-40 h, the biological contact oxidation pond g comprises an anoxic section and an aerobic section, the retention time of the aerobic section is more than 28h, and the volume load of the filler COD is designed to be 0.01-0.02 kgCOD/(m)³·d)；

The membrane bioreactor h is designed to have the sludge load of 0.01-0.02 BOD₅And (kgMLSS d), the designed retention time is 8-15 h, and the designed MLSS is 8000-10000 mg/L.

The heterogeneous catalysis ozone activated carbon adsorption reactor i is designed to have the reaction time of 0.5h, a heterogeneous catalysis reaction layer is arranged at the bottom of the reactor, and an activated carbon layer is arranged at the upper part of the reactor; the heterogeneous catalytic reaction layer is a magnetic nano composite filler, the magnetic nano composite filler is prepared by taking nickel-zinc ferrite as a magnetic core and hydrolyzing tetraethyl silicate; the design height of the filler is 0.3-0.5 m; the activated carbon layer is made of granular activated carbon, the particle size is 2-5 mm, and the height of the activated carbon layer is 2-3 m.

2. when the membrane bioreactor discharges water BOD₅Or when the COD concentration is more than the standard limit value of the reuse water, the volume load of the biological contact oxidation pond is reduced,the single adjustment amount is 5 gCOD/(m)³·d)；

the reuse water standard limits are shown in table 1.

Example 1

The wastewater generated by a certain polyester chemical industry enterprise mainly comprises substances such as benzene ring polymers, diethylene glycol, acetaldehyde, ethylene glycol, 2-methyl-1, oxalic acid and the like, and the wastewater contains substances which cause the esterification wastewater to have complex components and poor biochemical property, high COD (chemical oxygen demand), high N, P content and high treatment difficulty, and partial substances containing benzene ring structures are difficult to biodegrade; in the polyester production process, concentrated sulfuric acid is used as a catalyst for accelerating the reaction, so that the polyester wastewater has strong acidity, the pH is about 2-3, the discharge water amount is 500t/d of benzene ring polymer, 100t/d of diethylene glycol, 1000t/d of acetaldehyde and 300t/d of oxalic acid, the total discharge water amount is 2200t/d of other domestic and production wastewater, the water quality condition of inlet water is shown in table 2, and the inlet water is required to reach the recycling standard after being treated.

TABLE 2 index concentration of wastewater from enterprises

Item	Index (mg/L)	Item	Index (mg/L)
				SS	242	Chloride compound	1120
BOD₅	110	Total hardness (as CaCO)₃Meter)	950
				COD	755	Total alkalinity (as CaCO)₃Meter)	456
Iron	3.3	Total dissolved solids	1130
				Manganese oxide	1.2	Ammonia nitrogen	12.6
Total phosphorus	8.4	Petroleum products	1.5
				Volatile phenols	4.5	Total nitrogen	25

As a preferred embodiment, the design of the adjusting acid-adjusting tank is adjusted to have a volume retention time of 10h, the tank body is made of a concrete tank lining anticorrosive material, air stirring is adopted, and the stirring intensity is 0.4m³Air/(min. m)²Pool surface area), adjusting acid by using waste stock solution, and arranging a lifting water pump in the pool.

The function of the acid regulating pool is as follows:

As a preferred embodiment, the improved Fenton reactor is in a fluidized bed form, a special-shaped guide wall is arranged in the improved Fenton reactor, the special-shaped guide wall is in an inverted cone shape, and after the special-shaped guide wall is arranged, the Reynolds number of water flow of the system is increased, so that waste water is treatedThe water flow state is in a turbulent flow state, the mixing effect of the medicament and the wastewater is enhanced, the reaction time is greatly reduced, the rising flow rate of the system design is 1.75m/s, the reaction pH is 3-4, ferrous sulfate and hydrogen peroxide are added, 2.5mg/L ferrous is added according to the removal of 1mg/LCOD, and 1.25mg/LH is added₂O₂。

The improved Fenton reactor is particularly selected according to the characteristics of esterification wastewater, after the treatment of an acetaldehyde recovery technology, the COD is about 1000-5000, the wastewater contains substances such as benzene ring polymers, diethylene glycol, acetaldehyde and oxalic acid, the pH value of the wastewater is 2-4, a Fenton oxidation method is an efficient and economic advanced wastewater oxidation technology, hydrogen peroxide and ferrous ions react to generate hydroxyl radicals with strong oxidizing property, pollutants in the wastewater are oxidized and degraded, the oxidation effect on pollutants such as organic compound polycarboxylic acid, alcohol and esters is extremely remarkable, and the treatment effect is better under an acidic condition. Therefore, the invention selects the improved Fenton reactor, firstly, part of complex organic pollutants which are easy to be chemically oxidized can be removed, the load of electrochemical reaction is reduced, and secondly, the water treatment cost of the acid regulating part can be reduced by directly utilizing the characteristics of raw water.

As a preferred embodiment, the electrochemical reactor is in the form of a fluidized bed, and the mixing and the rising flow rate are increased by bottom aeration, and the aeration parameter is designed to be 0.8m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode and enhancing the corrosion resistance of the anode, and the titanium plate is used as a cathode and has the installed capacity of 1W/(m)³Water/h).

As a preferred embodiment, the sedimentation tank is a vertical flow sedimentation tank, the designed ascending flow rate is 0.15mm/s, Polyacrylamide (PAM) is added as a flocculating agent and directly added into a water inlet pipe of the sedimentation tank for hydraulic mixing, and the designed adding amount is 2.5 mg/L.

As a preferred embodiment, the mixing reaction time of the neutralization tank is designed to be 0.7h, waste alkali liquor or sodium hydroxide is added as a neutralizing agent, and the pH value of the added wastewater is 7-8.

As a preferred embodiment, the operation method of the primary pretreatment module is intermittentMulti-stage circulation reaction according to BOD of inlet organic matter₅The COD is 0.15, three-stage circulation is adopted, and the specific operation mode is as follows:

BOD of raw water₅When COD is 0.15 < 0.2, the flow sequence of the waste water is as follows: the coming water → the adjusting and acid adjusting pool → the improved Fenton reactor → the electrochemical reactor → the adjusting and acid adjusting pool → the improved Fenton reactor → the sedimentation tank → the neutralization pool → the yielding water; the total reaction time of the system is 4.9-5.7 h, wherein the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the electrochemical reactor is 0.1-0.2 h, the adjusting and acid adjusting pool is 0.5h, the improved Fenton reactor is 0.4-0.6 h, the sedimentation pool is 1.5h and the neutralization pool is 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and acid adjusting pool, 15% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and acid adjusting pool, 15% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization pool;

compared with the primary circulation and the secondary circulation, the operation mode has the advantages that the total reaction time of Fenton is 1.5 hours, the electrochemistry is 0.2 hour, but the COD removal rate of the reaction is improved by 8-11%, the dosage is reduced by 5-8%, the sludge yield is reduced by 3-5%, and the reason for improving the removal rate and reducing the dosage is that the pollutant forms are gradually changed by the alternate oxidation reaction and the electrochemical reaction, so that the degradation of complex microorganisms is realized. Firstly breaking one or more chains of a long-chain compound through one chemical oxidation reaction to generate a new compound, then breaking one or more chains of the long-chain compound through one electrochemical reaction to generate a new compound, and then completely changing the long-chain compound into a compound which is short-chain, easy to treat, biological to treat and low in toxicity through 1 or 2 times of circulation. Therefore, the phenomenon that the COD in the wastewater cannot be further reduced by adding excessive oxidant in the actual engineering can occur, but the operation mode of the invention can well solve the problem through gradual reaction and can also obviously reduce the operation cost. Particularly, the invention aims at the esterification wastewater treated by the acetaldehyde recovery technology, and the situation that partial maintenance of the acetaldehyde recovery technology treatment is stopped can occur in the actual operation, and aiming at the situation, the operation mode of the primary pretreatment module adopted by the invention can bear the change of higher COD, so that the system can normally operate under the condition that the pretreatment cannot operate, the removal of pollutants is realized by increasing the dosage and increasing the cycle number, and the influence on the subsequent biochemical module is reduced.

As a preferred embodiment, the internal and external double reinforced circulation anaerobic reactor is a new generation of high-efficiency anaerobic reactor, wastewater flows from bottom to top in the reactor, pollutants are adsorbed and degraded by bacteria, and purified water flows out from the upper part of the reactor; the reactor is divided into 5 zones from bottom to top according to the function division, namely a mixing zone, a 1 st anaerobic zone, a 2 nd anaerobic zone, a settling zone and a gas-liquid separation zone, and the reactor is characterized in that an external circulation system is added on the basis of an internal circulation anaerobic reactor, and the flow of an external circulation pump can be automatically controlled according to the water quality during operation so as to achieve smaller floor area and better treatment effect.

The reason for selecting the internal and external reinforced circulation anaerobic reactor is that most pollutants which are difficult to degrade are degraded after the esterification wastewater is treated by electrochemistry and fenton, but because the components of the esterification wastewater are complex and the toxicity is strong, a process capable of bearing larger impact load must be selected, and an IC (internal circulation) reactor is the anaerobic biological process of which the anaerobic biological reactor has the most impact resistance, and is improved on the basis of the process, and the circulation flow is increased, so that the impact load resistance strength is further enhanced.

In a preferable embodiment, the internal reinforced circulation is that the water outlet of the first reaction chamber returns to the water inlet end, and the ratio a of the internal circulation flow to the water inlet flow is 4;

in a preferable embodiment, the external forced circulation is that the effluent of the second reaction chamber returns to the water inlet end, and the ratio b of the external circulation flow to the water inlet flow is 4.55;

a large amount of circulating water and inlet water are fully mixed, so that harmful substances in raw water are fully diluted, and the influence of poisons on the anaerobic digestion process is greatly reduced.

As a preferred embodiment, the biological contact oxidation pond is designed to have a total retention time of 35h and comprises an anoxic section and an aerobic section, wherein the retention time of the aerobic section is more than 28h, and the volume load of COD (chemical oxygen demand) of the filler is designed to be 0.015 kgCOD/(m)³D); the design of the biological contact oxidation pond simultaneously meets the technological requirements for further removing COD, nitrogen and phosphorus, and particularly meets the requirement of effluent on N, P indexes. The esterification wastewater aimed by the invention has the characteristics of poor biochemical property, the biochemical property is improved after pretreatment and anaerobic treatment, but compared with the common wastewater, the biochemical property is still poor, the wastewater has certain toxicity, and the effluent has higher requirement on N, P, so the biological contact oxidation process with stronger impact resistance is selected.

In a preferred embodiment, the membrane bioreactor is designed to have a sludge load of 0.01BOD₅/(kgMLSS d), the designed residence time is 15h and the designed MLSS is 10000 mg/L. The membrane bioreactor is selected by considering that the BOD index of the esterified wastewater is low, the influent water does not meet the requirements of biochemical nitrogen removal and biochemical phosphorus removal, a part of N and P can be removed in the biological contact oxidation tank, but the index requirements of the effluent N and P are high, and the reuse water has high requirements on total hardness, total alkalinity, iron and manganese, so that the membrane bioreactor is arranged and various pollutants in the wastewater are removed.

As a preferred embodiment, the heterogeneous catalysis ozone activated carbon adsorption reactor is designed to have the reaction time of 0.5h, a heterogeneous catalysis reaction layer is arranged at the bottom of the reactor, and an activated carbon layer is arranged at the upper part of the reactor; the heterogeneous catalytic reaction layer is a magnetic nano composite filler, the magnetic nano composite filler is prepared by taking nickel-zinc ferrite as a magnetic core and hydrolyzing tetraethyl silicate; the designed height of the filler is 0.5 m; the activated carbon layer is made of granular activated carbon, the grain diameter is 3mm, and the height of the activated carbon layer is 3 m. The sewage and the ozone enter from the bottom of the reactor together, are simply mixed at the bottom, then are subjected to the enhanced oxidation reaction of the heterogeneous catalytic reaction layer, and finally enter the activated carbon layer for the adsorption reaction.

As a preferred embodiment, the ozone activated carbon adsorption reactor is arranged for realizing that the effluent reaches the reuse water standard because the esterification wastewater is extremely difficult to treat, and some continuous Fenton, electrochemistry and long-time biochemical reactions cannot be removed, and finally the continuous Fenton, electrochemistry and long-time biochemical reactions are removed through heterogeneous ozone oxidation and activated carbon adsorption.

As a preferred embodiment, the modular integrated process for treating chemical recovery wastewater comprises the steps of comparing and analyzing the real-time online water quality monitoring results of the water inlet and outlet ends of each module and each submodule with the reuse water standard, outputting the results to an automatic control system, sending control signals to each module or each submodule unit by the automatic control system, and adjusting the operation modes and parameters of each module and each submodule, wherein the specific control method comprises the following steps:

example 2

The index concentration of the wastewater generated by a certain polyester chemical industry enterprise A is shown in Table 2, and the wastewater is required to reach the recycling standard after being treated.

TABLE 2A index concentration of wastewater from enterprises

Item	Index (mg/L)	Item	Index (mg/L)
				SS	242	Chloride compound	1120
BOD₅	155	Total hardness (as CaCO)₃Meter)	950
				COD	1755	Total alkalinity (as CaCO)₃Meter)	456
Iron	10.3	Total dissolved solids	1130
				Manganese oxide	5.6	Ammonia nitrogen	12.6
Total phosphorus	4.4	Petroleum products	1.5
				Volatile phenols	9.5	Total nitrogen	25

Step one, wastewater enters an adjusting acid regulating tank for temporary storage, adjustment and acid regulation, the adjusting acid regulating tank is designed to adjust the volume retention time to be 10.8h, a concrete tank lining is adopted as a tank body, air stirring is adopted, and the designed stirring strength is 0.4m³Air/(min. m)²Pool surface area), adjusting acid by adopting concentrated sulfuric acid, and arranging 4 lifting water pumps in the pool.

Step two, measuring BOD and COD indexes of raw water on line, calculating the B/C of the raw water to be 0.07, and operating a three-stage circulation mode, namely incoming water → an acid regulation tank → an improved Fenton reactor → an electrochemical reactor → the acid regulation tank → the improved Fenton reactor → the electrochemical reactor → the acid regulation tank → the improved Fenton reactor → a sedimentation tank → a neutralization tank → water outlet; the total reaction time of the system is 4.15h, wherein the adjusting and acid adjusting tank is 0.5h, the improved Fenton reactor is 0.45h, the electrochemical reactor is 0.15h, the adjusting and acid adjusting tank is 0.5h, the improved Fenton reactor is 0.45h, the sedimentation tank is 1.5h, and the neutralization tank is 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and acid adjusting pool, 15% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and acid adjusting pool, 15% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization pool;

the following two reaction conditions were experimentally demonstrated under the same residence time conditions:

① Fenton for 1.35 h-electrochemistry for 0.3h

② Fenton for 0.45h, electrochemistry for 0.15h, Fenton for 0.45h

The same point of the two is that the total reaction time of Fenton is 1.35 hours, the electrochemistry is 0.3 hours, but the COD removal rate of reaction ② is improved by 8-11% compared with reaction ①, the dosage is reduced by 5-8%, the sludge yield is reduced by 3-5%, the reason for improving the removal rate and reducing the dosage is that the pollutant form is gradually changed by the alternate oxidation reaction and the electrochemical reaction, thereby realizing the degradation of complex microorganisms, namely, firstly, one or more chains of a long-chain compound are broken by one-time chemical oxidation reaction to generate a new compound, then, one or more chains of the long-chain compound are broken by one-time electrochemical reaction to generate a new compound, and then, through 2 times of circulation, the long-chain compound is thoroughly changed into a short-chain compound which is easy to treat, can be biologically treated and has low toxicity.

Step three, enabling the wastewater to enter an improved Fenton reactor, removing complex organic matters, and improving the biodegradability of the wastewater, wherein the improved Fenton reactor is in a fluidized bed form, a special-shaped guide wall is arranged inside the improved Fenton reactor, the special-shaped guide wall is in an inverted cone shape, the designed system design ascending flow rate is 1.8m/s, the reaction pH is 3-4, and 658mg/L of ferrous sulfate and 1206mg/L of hydrogen peroxide are added;

step four, the wastewater enters an electrochemical reactor, long chains in pollutants are broken, the molecular number and the toxicity of the pollutants are reduced, the electrochemical reactor is in a fluidized bed form, bottom aeration is adopted for mixing and increasing the ascending flow velocity, and the aeration quantity parameter is designed to be 0.93m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode and enhancing the corrosion resistance of the anode, and the titanium plate is used as a cathode and has the installed capacity of 1.2W/(m)³Water/h);

step five, the wastewater enters an adjusting and acid-regulating pool for adjusting and regulating acid, the pH of the adjusted wastewater is 3-4, and concentrated sulfuric acid is used for regulating acid;

step six, enabling the wastewater to enter an improved Fenton reactor, removing complex organic matters generated after electrochemical reaction, improving the biodegradability of the wastewater, and adding 336mg/L of ferrous sulfate and 615mg/L of hydrogen peroxide;

step seven, the wastewater enters an electrochemical reactor, medium chains in the pollutants are broken, heavy metal ions, namely iron and manganese, are removed, and the molecular number and toxicity of the pollutants are further reduced;

step eight, the wastewater enters an adjusting and acid-regulating pool for adjusting and regulating acid, the pH of the adjusted wastewater is 3-4, and concentrated sulfuric acid is used for regulating acid;

step nine, the wastewater enters an improved Fenton reactor, complex organic matters converted after electrochemical reaction are further removed, the biodegradability of the wastewater is improved, and 171mg/L of ferrous sulfate and 313mg/L of hydrogen peroxide are added;

step ten, enabling the wastewater to enter a sedimentation tank for coagulation sedimentation, removing organic matters in the wastewater, and reducing total soluble solids of the wastewater, wherein the sedimentation tank is a vertical flow sedimentation tank, the designed ascending flow rate is 0.14mm/s, Polyacrylamide (PAM) is added as a flocculating agent and directly added into a water inlet pipe of the sedimentation tank, and the designed adding amount is 2 mg/L;

step eleven, the wastewater enters a neutralization tank, the pH value is adjusted, the influence of the pH value on subsequent biochemical reaction is avoided, the mixing reaction time of the neutralization tank is designed to be 0.5h, waste alkali liquor is added to serve as a neutralizing agent, and the pH value of the added wastewater is 7-8.

Step twelve, measuring the COD value of the neutralization tank on line, and performing primary pretreatment to obtain 349mg/L COD in the wastewater;

thirteen, the waste water enters an internal and external reinforced circulation anaerobic reactor to remove pollutants, reduce toxicity, remove phosphorus and remove volatile phenol, the reason for selecting the internal and external reinforced circulation anaerobic reactor is that most of pollutants which are extremely difficult to degrade are degraded after the esterification waste water is treated by electrochemistry and fenton, but because the components of the esterification waste water are complex and the toxicity is strong, a process which can bear larger impact load must be selected, an IC (internal circulation) reactor is the most impact-resistant anaerobic biological process of the anaerobic biological reactor, the improvement is carried out on the basis of the process, the circulation flow is increased, a large amount of circulating water and inlet water are fully mixed, harmful substances in the raw water are fully diluted, the influence of the toxic substances on the anaerobic digestion process is greatly reduced, and the impact load resistance strength of the reactor is further enhanced. Designing the ratio a of the internal circulation flow to the water inlet flow to be 2; the ratio b of the external circulation flow to the water inlet flow is 0;

step fourteen, the wastewater enters a biological contact oxidation tank, organic matters in the wastewater are further removed, COD, BOD, ammonia nitrogen, total nitrogen and total phosphorus are reduced, the total retention time of the biological contact oxidation tank is designed to be 31.5h, the biological contact oxidation tank comprises an anoxic section and an aerobic section, the retention time of the aerobic section is 28h, and the volume load of filler COD is designed to be 0.013kgCOD/(m & lt/m & gt³D); the design of the biological contact oxidation pond simultaneously meets the technological requirements for further removing COD, nitrogen and phosphorus, and particularly meets the requirement of effluent on N, P indexes. The esterification wastewater aimed by the invention has the characteristics of poor biochemical property, the biochemical property is improved after pretreatment and anaerobic treatment, but compared with the common wastewater, the biochemical property is still poor, the wastewater has certain toxicity, and the effluent has higher requirement on N, P, so the biological contact oxidation process with stronger impact resistance is selected.

Fifteen, the wastewater enters a membrane bioreactor to remove SS, chloride, total hardness, total alkalinity, total dissolved solids, petroleum, BOD, COD, iron, manganese, total nitrogen and total phosphorus in the wastewater, and the membrane bioreactor is designed to have a sludge load of 0.01BOD₅V (kgMLSS d), design residence time 10h, setThe MLSS is 8500 mg/L. The membrane bioreactor is selected by considering that the BOD index of the esterified wastewater is low, the influent water does not meet the requirements of biochemical nitrogen removal and biochemical phosphorus removal, a part of N and P can be removed in the biological contact oxidation tank, but the index requirements of the effluent N and P are high, and the reuse water has high requirements on total hardness, total alkalinity, iron and manganese, so that the membrane bioreactor is arranged to remove various pollutants in the wastewater.

Sixthly, monitoring various indexes of the wastewater to meet the requirement of reuse water, and ending the process.

Example 3

The index concentration of wastewater generated by a certain polyester chemical industry enterprise B is shown in Table 3, and the wastewater is required to reach the recycling standard after being treated.

TABLE 3B index concentration of wastewater from enterprises

Item	Index (mg/L)	Item	Index (mg/L)
				SS	240	Chloride compound	600
BOD₅	340	Total hardness (as CaCO)₃Meter)	850
				COD	1870	Total alkalinity (as CaCO)₃Meter)	380
Iron	3.3	Total dissolved solids	1350
				Manganese oxide	1.2	Ammonia nitrogen	22.2
Total phosphorus	8.4	Petroleum products	3.5
				Volatile phenols	4.5	Total nitrogen	60

Step one, wastewater enters an adjusting acid regulating tank for temporary storage, adjustment and acid regulation, the adjusting acid regulating tank is designed to adjust the volume retention time to be 10.8h, a concrete tank lining is adopted as a tank body, air stirring is adopted, and the designed stirring strength is 0.35m³Air/(min. m)²Pool surface area), adjusting acid by adopting concentrated sulfuric acid, and arranging 4 lifting water pumps in the pool.

Step two, measuring BOD and COD indexes of raw water on line, calculating the B/C of the raw water to be 0.18, and operating a secondary circulation mode, namely incoming water → an acid regulation tank → an improved Fenton reactor → an electrochemical reactor → the acid regulation tank → the improved Fenton reactor → a sedimentation tank → a neutralization tank → water outlet; the total reaction time of the system is 4.2h, wherein the adjusting acid adjusting tank runs for 0.5h, the improved Fenton reactor runs for 0.5h, the electrochemical reactor runs for 0.2h, the adjusting acid adjusting tank runs for 0.5h, the improved Fenton reactor runs for 0.5h, the sedimentation tank runs for 1.5h, and the neutralization tank runs for 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and adjusting acid tank, 20% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization tank;

step three, enabling the wastewater to enter an improved Fenton reactor, removing complex organic matters, and improving the biodegradability of the wastewater, wherein the improved Fenton reactor is in a fluidized bed form, a special-shaped guide wall is arranged inside the improved Fenton reactor, the special-shaped guide wall is in an inverted cone shape, the rising flow rate of a designed system is 1.8m/s, the reaction pH is 3-4, and 748mg/L of ferrous sulfate and 1346.4mg/L of hydrogen peroxide are added;

step four, the wastewater enters an electrochemical reactor, long chains in pollutants are broken, the molecular number and the toxicity of the pollutants are reduced, the electrochemical reactor is in a fluidized bed form, bottom aeration is adopted for mixing and increasing the ascending flow velocity, and the aeration quantity parameter is designed to be 0.93m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode and enhancing the corrosion resistance of the anode, and the titanium plate is used as a cathode and has the installed capacity of 1.1W/(m)³Water/h);

step five, entering an adjusting and acid-regulating pool for adjusting and regulating acid, wherein the pH value of the waste water after adjustment is 3-4, and adopting a waste acid solution for regulating acid;

step six, the wastewater enters an improved Fenton reactor, complex organic matters generated after electrochemical reaction are removed, the biodegradability of the wastewater is improved, and 359mg/L of ferrous sulfate and 646mg/L of hydrogen peroxide are added;

step seven, enabling the wastewater to enter a sedimentation tank for coagulation sedimentation, removing organic matters in the wastewater, and reducing total soluble solids of the wastewater, wherein the sedimentation tank is a vertical flow sedimentation tank, the designed ascending flow rate is 0.15mm/s, Polyacrylamide (PAM) is added as a flocculating agent and directly added into a water inlet pipe of the sedimentation tank, and the designed adding amount is 2.7 mg/L;

and step eight, the wastewater enters a neutralization tank, the pH value is adjusted, the influence of the pH value on subsequent biochemical reaction is avoided, the mixing reaction time of the neutralization tank is designed to be 0.65h, waste alkali liquor is added to serve as a neutralizing agent, and the pH value of the added wastewater is 7-8.

Step nine, measuring the COD value of the neutralization tank on line, and performing primary pretreatment to obtain the COD in the wastewater of 646 mg/L;

step ten, the wastewater enters an internal and external reinforced circulation anaerobic reactor to remove pollutants, reduce toxicity, remove phosphorus and remove volatile phenol, the reason for selecting the internal and external reinforced circulation anaerobic reactor is that most of pollutants which are extremely difficult to degrade are degraded after the esterification wastewater is subjected to electrochemical and fenton treatment, but because the components of the esterification wastewater are complex and the toxicity is strong, a process capable of bearing larger impact load must be selected, an IC (internal circulation) reactor is the most impact-resistant anaerobic biological process of an anaerobic biological reactor, improvement is carried out on the basis of the process, the circulation flow is increased, a large amount of circulating water and inlet water are fully mixed, harmful substances in the raw water are fully diluted, the influence of the toxic substances on the anaerobic digestion process is greatly reduced, and the impact load resistance strength of the reactor is further enhanced. Designing the ratio a of the internal circulation flow to the water inlet flow to be 4; the ratio b of the external circulation flow to the water inlet flow is 3.5;

step eleven, enabling the wastewater to enter a biological contact oxidation tank, further removing organic matters in the wastewater, and reducing COD, BOD, ammonia nitrogen, total nitrogen and total phosphorus, wherein the total retention time of the biological contact oxidation tank is designed to be 38h, the biological contact oxidation tank comprises an anoxic section and an aerobic section, the retention time of the aerobic section is 34h, and the volume load of filler COD is designed to be 0.017kgCOD/(m & ltm & gt³D); the design of the biological contact oxidation pond simultaneously meets the technological requirements for further removing COD, nitrogen and phosphorus, and particularly meets the requirement of effluent on N, P indexes. The esterification wastewater aimed by the invention has the characteristics of poor biochemical property, the biochemical property is improved after pretreatment and anaerobic treatment, but compared with the common wastewater, the biochemical property is still poor, the wastewater has certain toxicity, and the effluent has higher requirement on N, P, so the biological contact oxidation process with stronger impact resistance is selected.

Step twelve, the wastewater enters a membrane bioreactor to remove the wastewaterSS, chloride, total hardness, total alkalinity, total dissolved solids, petroleum, BOD, COD, iron, manganese, total nitrogen and total phosphorus in the sludge, wherein the sludge load of the membrane bioreactor is designed to be 0.013BOD₅/(kgMLSS d), the design residence time is 12h, and the design MLSS is 9000 mg/L. The membrane bioreactor is selected by considering that the BOD index of the esterified wastewater is low, the influent water does not meet the requirements of biochemical nitrogen removal and biochemical phosphorus removal, a part of N and P can be removed in the biological contact oxidation tank, but the index requirements of the effluent N and P are high, and the reuse water has high requirements on total hardness, total alkalinity, iron and manganese, so that the membrane bioreactor is arranged to remove various pollutants in the wastewater.

And step thirteen, monitoring various indexes of the wastewater, wherein COD88mg/L is more than or equal to 50mg/L, total nitrogen 8.5mg/L is more than or equal to 5mg/L, and the requirement of reuse water is not met.

Fourteen steps, enabling the wastewater to enter a heterogeneous catalysis ozone activated carbon adsorption reactor for oxidation adsorption treatment, and further removing COD (chemical oxygen demand) and total nitrogen, wherein the designed reaction time of the heterogeneous catalysis ozone activated carbon adsorption reactor is 0.5h, a heterogeneous catalysis reaction layer is arranged at the bottom of the reactor, and an activated carbon layer is arranged at the upper part of the reactor; the heterogeneous catalytic reaction layer is a magnetic nano composite filler, the magnetic nano composite filler is prepared by taking nickel-zinc ferrite as a magnetic core and hydrolyzing tetraethyl silicate; the designed height of the filler is 0.4 m; the activated carbon layer is made of granular activated carbon, the particle size is 3-5 mm, and the height of the activated carbon layer is 2 m. The sewage and the ozone enter from the bottom of the reactor together, are simply mixed at the bottom, then are subjected to the enhanced oxidation reaction of the heterogeneous catalytic reaction layer, and finally enter the activated carbon layer for the adsorption reaction. The ozone activated carbon adsorption reactor aims to realize that the effluent reaches the reuse water standard because the esterification wastewater is extremely difficult to treat and certain even Fenton, electrochemistry and long-time biochemical reactions cannot be removed.

Claims

1. A modularized integrated process method for treating chemical recovered wastewater is characterized in that: the system comprises a three-level module, a first-level pretreatment module, a second-level biochemical module and a third-level advanced treatment module; the primary pretreatment module is provided with an adjusting and acid adjusting tank, an improved Fenton reactor, an electrochemical reactor, a sedimentation tank and a neutralization tank; the secondary biochemical module is provided with an anaerobic submodule and an aerobic submodule; the anaerobic submodule is an internal and external dual-reinforced circulation anaerobic reactor; the aerobic submodule comprises a biological contact oxidation pond and a membrane bioreactor; the three-stage advanced treatment module is provided with a heterogeneous catalysis ozone activated carbon adsorption reactor.

2. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the inlet of the adjusting and acid-regulating pool is connected with the outlet of a polyester industrial wastewater acetaldehyde recovery processing system, the outlet of the adjusting and acid-regulating pool is connected with the inlet of the improved Fenton reactor, the outlet of the improved Fenton reactor is connected with the inlet of the electrochemical reactor, the outlet of the electrochemical reactor is connected with the inlet of the sedimentation pool and the inlet of the adjusting and acid-regulating pool, the outlet of the sedimentation pool is connected with the inlet of the neutralization pool, and the effluent of the neutralization pool enters the secondary biochemical module;

the anaerobic submodule and the aerobic submodule are arranged in series; the inlet of the internal and external dual reinforced circulation anaerobic reactor is connected with the outlet of the neutralization tank, the outlet of the internal and external dual reinforced circulation anaerobic reactor is connected with the inlet of the biological contact oxidation tank, the outlet of the biological contact oxidation tank is connected with the inlet of the membrane bioreactor, and the effluent of the membrane bioreactor enters the three-stage advanced treatment module;

the three-stage advanced treatment module is provided with a heterogeneous catalysis ozone activated carbon adsorption reactor; the inlet of the heterogeneous catalysis ozone activated carbon adsorption reactor is connected with the outlet of the membrane bioreactor, and the outlet of the heterogeneous catalysis ozone activated carbon adsorption reactor is connected with the main discharge port;

3. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the operation method of the primary pretreatment module is an intermittent multi-stage circulating reaction according to BOD of inlet water organic matters₅The COD value designs three sets of operation modes, adopts first grade circulation, second grade circulation and tertiary circulation respectively, and specific operation mode is:

when raw water BOD₅When COD is less than 0.2, the flow sequence of the wastewater is as follows: the coming water → the adjusting and acid adjusting pool → the improved Fenton reactor → the electrochemical reactor → the adjusting and acid adjusting pool → the improved Fenton reactor → the sedimentation tank → the neutralization pool → the yielding water; the total reaction time of the system is 4.9-5.7 h, wherein the acid adjusting pool is adjusted for 0.5h, the improved Fenton reactor is adjusted for 0.4-0.6 h, and the electrochemical reactor is adjusted for 0.1-02h, adjusting the acid adjusting pool for 0.5h, improving the Fenton reactor for 0.4-0.6 h, performing the electrochemical reactor for 0.1-0.2 h, adjusting the acid adjusting pool for 0.5h, improving the Fenton reactor for 0.4-0.6 h, performing the sedimentation pool for 1.5h, and performing the neutralization pool for 0.5 h; the unit standard COD removal rate is respectively 0% of the adjusting and acidity adjusting tank, 15% of the improved Fenton reactor, 40% of the electrochemical reactor, 0% of the adjusting and acidity adjusting tank, 15% of the improved Fenton reactor, 10% of the sedimentation tank and 0% of the neutralization tank.

4. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the internal and external dual reinforced circulation anaerobic reactor is divided into a mixing zone, a 1 st anaerobic zone, a 2 nd anaerobic zone, a settling zone and a gas-liquid separation zone from bottom to top, wastewater flows in the reactor from bottom to top, an internal reinforced circulation and an external reinforced circulation system are added, and the flow of an internal and external circulation pump can be automatically controlled according to the water quality during operation;

。

5. the modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the improved Fenton reactor is in a fluidized bed form, a special-shaped guide wall is arranged inside the improved Fenton reactor and is in an inverted cone shape, the rising flow rate of the system design is 1.5-2 m/s, the reaction pH is 3-4, ferrous sulfate and hydrogen peroxide are added, the dosage is removed by 1mg/LCOD, and 2-3 mg/Liang is addedL ferrous sulfate and 1-1.5 mg/LH₂O₂。

6. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the electrochemical reactor is in a fluidized bed form, bottom aeration is adopted for mixing and increasing the ascending flow velocity, and the aeration parameter is designed to be 0.8-1 m³Air/(min. m)²The surface area of the pool) is increased by adopting a modified titanium plate as an anode to enhance the corrosion resistance of the anode, and the titanium plate is used as a cathode, and the installed capacity is 1-1.5W/(m)³Water/h).

7. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the total residence time of the biological contact oxidation tank is designed to be 30-40 h, the biological contact oxidation tank comprises an anoxic section and an aerobic section, the residence time of the aerobic section is more than 28h, and the volume load of filler COD is designed to be 0.01-0.02 kgCOD/(m)³·d)。

8. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the membrane bioreactor is designed to have the sludge load of 0.01-0.02 BOD₅And (kgMLSS d), the designed retention time is 8-15 h, and the designed MLSS is 8000-10000 mg/L.

9. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: the heterogeneous catalysis ozone activated carbon adsorption reactor is designed to have the reaction time of 0.5h, a heterogeneous catalysis reaction layer is arranged at the bottom of the reactor, and an activated carbon layer is arranged at the upper part of the reactor; the heterogeneous catalytic reaction layer is a magnetic nano composite filler, the magnetic nano composite filler is prepared by taking nickel-zinc ferrite as a magnetic core and hydrolyzing tetraethyl silicate; the design height of the filler is 0.3-0.5 m; the activated carbon layer is made of granular activated carbon, the particle size is 2-5 mm, and the height of the activated carbon layer is 2-3 m.

10. The modular integrated process method for chemical recovery wastewater treatment according to claim 1, characterized in that: according to the real-time on-line water quality monitoring results of the water inlet end and the water outlet end of each module and each submodule, comparing and analyzing the results with the reuse water standard, outputting the results to an automatic control system, sending control signals to each module or each submodule unit by the automatic control system, and adjusting the operation modes and parameters of each module and each submodule, wherein the specific control method comprises the following steps:

1) when the concentration of SS (suspended solid) or total dissolved solids or volatile phenol in the effluent of the membrane bioreactor is greater than the standard limit value of reuse water, the effluent enters a heterogeneous catalytic ozone activated carbon adsorption reactor;

2) when the membrane bioreactor discharges water BOD₅Or when the COD concentration is greater than the standard limit value of the recycled water, the volume load of the biological contact oxidation pond is reduced, and the single adjustment amount is 5 gCOD/(m)³·d)；

3) When the concentration of ammonia nitrogen or total nitrogen in the effluent of the membrane bioreactor is greater than the standard limit value of reuse water, the yield of sludge is improved, and the single adjustment amount is 0.01 kgMLSS/kgCOD;

4) when the total phosphorus concentration of the effluent of the membrane bioreactor is greater than the standard limit value of the reuse water, reducing the ascending flow rate of the sedimentation tank, wherein the single adjustment amount is 0.05mm/s, and increasing the adding amount of Polyacrylamide (PAM), wherein the single adjustment amount is 0.2 mg/L;

5) when the total hardness or the total alkalinity of the effluent of the membrane bioreactor is greater than the standard limit value of the recycled water, the designed mixed reaction time of the neutralization pond is increased, and the single adjustment amount is 0.1 h;

6) when the concentration of iron or manganese in the inlet water of the electrochemical reactor is greater than the standard limit value of the recycled water, the installed capacity is reduced, and the single adjustment amount is 0.1W/(m)³Water/h);

the reuse water standard limit is shown in table 1:

TABLE 1 Standard Limit value of reuse Water

。