CN113292196A

CN113292196A - Method and system for treating pesticide wastewater mother liquor

Info

Publication number: CN113292196A
Application number: CN202011626858.0A
Authority: CN
Inventors: 陈福泰; 刘兴甜; 白立强; 马建波; 刘栋
Original assignee: Weifang Qingdahua Environmental Resources Co ltd; Go Higher Environment Group Co ltd
Current assignee: Weifang Qingdahua Environmental Resources Co ltd; Go Higher Environment Group Co ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-08-24

Abstract

The invention discloses a method and a system for treating pesticide wastewater mother liquor, wherein the system comprises a pretreatment system, a low-temperature evaporation system, an ozone reaction system and an MBR biochemical system which are sequentially connected. The method and the system can treat the dangerous waste liquid with the salt content of more than 20 percent and the COD concentration of more than 20 ten thousand ppm, and also can treat the dangerous waste liquid with the salt content of about 10 percent and the medium degree of COD concentration of about 10 ten thousand ppm. The method and the system disclosed by the application are not limited to the treatment of the pesticide wastewater mother liquor, and can also be applied to other MVR evaporation mother liquor or waste liquor with high salt, high organic matters and difficult biochemical treatment.

Description

Method and system for treating pesticide wastewater mother liquor

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a method and a system for treating pesticide wastewater mother liquor.

Background

The pesticide wastewater refers to wastewater discharged by pesticide factories in the pesticide production process, and the wastewater contains high-concentration toxic and harmful organic pollutants, is complex in component, has more difficultly-degradable substances and has higher inorganic salt concentration. The pesticide waste water contains salt, COD is tens of thousands of milligrams per liter, and the pesticide residue toxic substances are about 0.6 percent, and the waste water is treated by a concentration incineration method or a wet oxidation method. In the concentration incineration method, more than 50% of waste water still remains after concentration and decrement of a conventional evaporator, the waste water is directly incinerated or handed to a hazardous waste disposal unit, the disposal cost is huge, meanwhile, the COD value of a conventional evaporated solution is about 2 ten thousand ppm, the BOD/COD value is less than 0.1, the biodegradability is poor, and the difficulty and the cost for treating the evaporated mother liquor by the conventional process are huge; although the wet oxidation method can efficiently degrade organic matters in the wastewater, the method has certain limitations: the method needs to be carried out under the conditions of high temperature and high pressure, has the problems of equipment corrosion and safety, and has large one-time investment of an equipment system; the reaction condition needs to be kept at high temperature and high pressure all the time, and is only suitable for treating high-concentration small-flow wastewater; meanwhile, a more toxic intermediate product is easily generated in the wet oxidation process, so that the large-scale application of the wet oxidation process is limited. Because the pesticide wastewater has no more economical and applicable treatment process and equipment, pesticide manufacturers often concentrate the pesticide wastewater into mother liquor for temporary storage and deliver the mother liquor to a third party for treatment.

Based on the defects, the invention provides a high-efficiency, energy-saving and environment-friendly treatment method and system for mother liquor after evaporation and decrement of pesticide wastewater.

Disclosure of Invention

The invention mainly aims to solve the defects of high treatment difficulty, high treatment cost, incomplete removal of salt or organic matters and the like in the prior art, and provides a method and a system for treating pesticide wastewater mother liquor with low cost, reduction and harmlessness.

To achieve the above object, the present invention provides

A method for treating pesticide wastewater mother liquor comprises the following steps:

s1, pretreatment: adjusting the pH value of the pesticide wastewater mother liquor to 7.5-8.5, and then separating and precipitating to obtain a pretreatment mother liquor;

s2, low-temperature evaporation: the pretreatment mother liquor obtained in the step S1 is subjected to low-temperature evaporation by a low-temperature evaporation system at the temperature of-95.5 to-93.7 kpa and the temperature of 35 to 40 ℃, and evaporated waste gas is condensed to obtain condensed evaporation liquid;

s3, ozone reaction: carrying out catalytic reaction on the condensed evaporation liquid obtained in the step S2 through an ozone reaction system to obtain an ozone catalytic liquid;

s4, conveying the ozone catalytic liquid obtained in the step S3 to an aerobic tank provided with an MBR (membrane bioreactor) for treatment through a regulating tank, wherein aerobic sludge is filled in the aerobic tank, a membrane module is arranged in the MBR, the aperture of a separation membrane on the membrane module is less than or equal to 0.1um, the ozone catalytic liquid firstly enters the aerobic tank to react with the aerobic sludge, then macromolecular substances are intercepted through the membrane module of the MBR, and the solution penetrating through the membrane module is purified wastewater meeting the emission standard;

s5, carrying out filter pressing separation on the salt-containing slag concentrated solution obtained in the step S2, returning the separated liquid to S1 for continuous treatment, and conveying the separated solid salt slag and the precipitate obtained in the step S1 to a residue treatment system together.

Preferably, the residue treatment system is an incineration treatment system, and the solid salt slag and the precipitate are incinerated to remove organic matters, so that harmless treatment is realized.

Preferably, the residue treatment system is a safe landfill system, and the solid salt slag and the sediment are packaged by ton bags and then conveyed to a rigid landfill site for safe landfill.

Preferably, step S1 uses sodium hydroxide to adjust the pH of the pesticide wastewater mother liquor.

Preferably, the ozone reaction system in step S3 includes an ozone generator, an ozone catalytic oxidation reactor, and an ozone tail gas destructor connected in sequence;

preferably, the ozone generator is used for preparing ozone and delivering the ozone to the ozone catalytic oxidation reactor;

preferably, the ozone catalytic oxidation reactor is provided with an ozone inlet, a condensed evaporative liquid inlet, a tail gas outlet and an ozone catalytic liquid outlet, the catalyst is filled in the ozone catalytic oxidation reactor, the filling rate is greater than 70%, the ozone catalytic oxidation reactor is further provided with a microporous aerator in the ozone catalytic oxidation reactor, the microporous aerator is used for enabling ozone to be uniformly distributed in a small state and to perform catalytic reaction with the condensed evaporative liquid, tail gas and the ozone catalytic liquid are generated through reaction, and the tail gas is discharged and conveyed to the ozone tail gas destructor and then discharged after treatment.

The invention also provides a treatment system of the pesticide wastewater mother liquor, which comprises a pretreatment system, a low-temperature evaporation system, an ozone reaction system and an MBR biochemical system which are connected in sequence;

the pretreatment system is used for adjusting the pH value of the pesticide wastewater mother liquor, separating precipitates generated by pH adjustment to obtain a pretreatment mother liquor, discharging the pretreatment mother liquor, and conveying the pretreatment mother liquor to the low-temperature evaporation system;

the low-temperature evaporation system comprises an evaporation tank and a condenser which are sequentially connected, the evaporation tank is provided with a vacuum device, the vacuum degree of the evaporation tank can reach a set threshold value, the pretreated mother liquor is evaporated at a set low temperature, evaporated waste gas is discharged and conveyed to the condenser, condensed evaporation liquid is obtained after condensation of the condenser, and the condensed evaporation liquid is discharged and conveyed to the ozone reaction system;

the ozone reaction system comprises an ozone catalytic oxidation reactor, wherein a catalyst is filled in the ozone catalytic oxidation reactor and is used for enabling the condensed evaporated liquid to generate an ozone catalytic reaction under the action of the catalyst to obtain an ozone catalytic liquid, and the ozone catalytic liquid is discharged and conveyed to the MBR biochemical system;

the MBR biochemical system comprises an aerobic tank and an MBR membrane bioreactor positioned in the aerobic tank, and aerobic sludge is filled in the aerobic tank; a membrane module is arranged in the MBR membrane bioreactor, and the aperture of a separation membrane on the membrane module is less than or equal to 0.1 um; the MBR biochemical system is used for enabling the ozone catalytic liquid to firstly enter the aerobic tank to react with the aerobic sludge, then intercepting macromolecular substances through a membrane module of the membrane bioreactor, and obtaining the solution penetrating through the membrane module as the purified wastewater meeting the discharge standard.

Preferably, the pretreatment regulating system comprises a pretreatment regulating tank and a solid-liquid separation device, wherein the pretreatment regulating tank is provided with a pesticide wastewater mother liquor inlet, a pH regulator inlet and an outlet, and the outlet is connected with the solid-liquid separation device;

preferably, the pesticide wastewater mother liquor enters the pretreatment regulating tank through the pesticide wastewater mother liquor inlet, reacts with the pH regulating agent entering through the pH regulating agent inlet, is discharged through the outlet, is conveyed to the solid-liquid separation device, is separated and precipitated, and is discharged and conveyed to the low-temperature evaporation system.

Preferably, the low-temperature evaporation system further comprises a heat exchanger connected with the evaporation tank;

preferably, the pretreatment mother liquor firstly passes through the heat exchanger, exchanges heat and then enters the evaporation tank.

Preferably, the ozone reaction system further comprises an ozone generator connected with the ozone catalytic oxidation reactor, and an ozone tail gas destructor;

Preferably, the ozone inlet and the condensed evaporation liquid inlet are positioned at the bottom of the catalytic ozonation reactor, and the tail gas outlet and the ozone catalytic liquid outlet are positioned at the top of the catalytic ozonation reactor.

Preferably, the ozone catalytic liquid also comprises an adjusting tank, wherein two ends of the adjusting tank are respectively connected with the ozone reaction system and the MBR biochemical system, and the ozone catalytic liquid enters the MBR biochemical system after being adjusted by the adjusting tank.

Preferably, the membrane bioreactor also comprises a box body and an aeration system, the membrane module and the aeration system are both positioned in the box body, and the aeration system is positioned below the membrane module.

By adopting the method and the system, the high-difficulty dangerous waste liquid with the salt content of more than 20 percent and the COD concentration of more than 20 ten thousand ppm can be treated, the medium-level dangerous waste liquid with the salt content of about 10 percent and the COD concentration of about 10 ten thousand ppm can also be treated, the whole method does not use any additional medicament except the pH regulator, the generation of additional waste is avoided, and the effluent can be directly discharged or recycled; the method greatly concentrates, reduces and retreats the mother liquor by adopting low-temperature evaporation with lower energy consumption, and can overcome the problem of high cost of direct incineration treatment; the residue obtained after evaporation can be finally treated in a harmless way no matter incineration or safe landfill is adopted; the system has compact and reasonable design, small occupied area of equipment and low investment cost and operation cost.

Drawings

FIG. 1 is a schematic structural view of a pesticide wastewater treatment system provided by the invention.

The system comprises a pretreatment adjusting tank 10, a solid-liquid separation device 12, a low-temperature evaporation system 20, a heat exchanger 21, an evaporation box 22, a vacuum device 23, a condenser 24, an ozone reaction system 30, an ozone catalytic oxidation reactor 31, an ozone tail gas destructor 32, an ozone generator 33, a microporous aerator 34, an MBR 40 biochemical system 41, an aerobic tank 42, an MBR 42, a membrane module 43, an aeration system 44 and an adjusting tank 50.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a method for treating pesticide wastewater mother liquor, which comprises the following steps:

s1, pretreatment: adjusting the pH value of the pesticide wastewater mother liquor to 7.5-8.5, and then separating and precipitating to obtain a pretreatment mother liquor; because acidic or alkaline substances are remained in the pesticide wastewater mother liquor, the pH of the pesticide wastewater mother liquor is adjusted through pretreatment, so that the pesticide wastewater mother liquor is alkalescent and meets the discharge standard, the subsequent treatment is convenient after the pH adjustment, and insoluble particle suspended matters, grease and the like in water can be removed;

s2, low-temperature evaporation: carrying out low-temperature evaporation on the pretreated mother liquor obtained in the step S1 through a low-temperature evaporation system at the temperature of-95.5 to-93.7 kpa and at the temperature of 35 to 40 ℃ to obtain salt slag-containing concentrated liquor and evaporation waste gas, and condensing the evaporation waste gas to obtain condensed evaporation liquor; because the pretreatment is only pH neutralization adjustment treatment, a large amount of salt, toxic substances, organic substances and the like still remain in the pesticide wastewater mother liquor after the pretreatment, 90-95% of water contained in the mother liquor can be evaporated out under the conditions of-95.5 to-93.7 kpa and 35-40 ℃ through a low-temperature evaporation system, the residual waste salt and high-boiling-point organic substances are salt-containing slag concentrated solution, and the evaporated waste gas is condensed to enter the subsequent treatment after removing the salt, most of the organic substances and other pollutants; and by setting vacuum of-95.5 to-93.7 kpa, steam can be formed at 35 to 40 ℃, 90 to 95 percent of water contained in the mother liquor is evaporated, so that the problems of energy consumption increased by steam formed at the temperature of more than 90 ℃ in conventional evaporation, and adhesion and scaling of water scales and organic matters on evaporation equipment due to overhigh temperature are avoided;

s3, ozone reaction: carrying out catalytic reaction on the condensed evaporation liquid obtained in the step S2 through an ozone reaction system to obtain an ozone catalytic liquid; after the pesticide wastewater mother liquor is pretreated and evaporated at low temperature, pollutants such as toxic substances, organic substances and the like are also remained, and the toxic substances and the organic components are degraded by ozone catalytic reaction by utilizing the strong oxidizing property of ozone and the adsorption and catalytic properties of a catalyst, when the BOD/COD value in the wastewater is lower than 0.3, the wastewater is difficult to be effectively treated by biochemical reaction, and the undegraded organic components in the wastewater subjected to low-temperature evaporation treatment can be further degraded by ozone catalytic oxidation reaction, so that the biodegradability of the wastewater is improved, and the subsequent biochemical treatment is facilitated;

s4, conveying the ozone catalytic liquid obtained in the step S3 to an aerobic tank provided with an MBR (membrane bioreactor) for treatment, wherein aerobic sludge is filled in the aerobic tank, a membrane module is arranged in the MBR, the aperture of a separation membrane on the membrane module is less than or equal to 0.1um, the ozone catalytic liquid firstly enters the aerobic tank to react with the aerobic sludge, then macromolecular substances are intercepted by the membrane module of the membrane bioreactor, and the solution penetrating through the membrane module is purified wastewater meeting the discharge standard; after the treatment of the previous 3 steps, organic matters still remain in the pesticide wastewater mother liquor, the invention combines the MBR technology for treatment, and the Membrane Bioreactor (MBR) is used as a novel sewage treatment method, organically combines the membrane separation and biological treatment technology, replaces a secondary sedimentation tank in the traditional activated sludge system (CAS), and improves the sludge-water separation efficiency. Compared with the traditional CAS, the MBR has the advantages of good effluent quality, small occupied area, low sludge yield and the like, the pesticide wastewater mother liquor treated in the first 3 steps firstly enters the aerobic tank to be subjected to aerobic treatment, so that organic matters are sufficiently digested and degraded, macromolecular substances are intercepted by the membrane component, pollutants such as suspended matters, bacteria, toxic substances and the like in water are further removed, and the effluent quality is ensured to meet the discharge standard.

S5, performing filter pressing separation on the salt-containing slag concentrated solution obtained in the step S2, returning the separated liquid to S1 for continuous treatment, conveying the separated solid salt slag and the precipitate obtained in the step S1 together to a residue treatment system, and performing resource recycling or harmless landfill.

Therefore, the invention can treat the highly polluted pesticide wastewater mother liquor by combining the pretreatment, the low-temperature evaporation technology, the ozone catalysis technology and the MBR membrane biological reaction technology. Firstly, pretreatment is adopted, the pH value of the pesticide wastewater mother liquor is adjusted to be neutral, insoluble particles can be removed, the influence of the pH value on subsequent treatment is reduced, particularly, ozone catalysis is sensitive to reaction conditions, the mother liquor after pH adjustment is evaporated at low temperature, salt and partial organic matters in the mother liquor are separated, the influence of the salt on the ozone catalysis is further reduced, and a small amount of salt, organic matters and toxic substances are remained in the mother liquor after the treatment, the BOD/COD value is less than 0.3, the biodegradability of the wastewater is poor, and toxic substances and partial organic matters are catalyzed and degraded by ozone, the biodegradability is improved, and finally, the MBR membrane biological reaction technology is adopted, and the aerobic-membrane module dual treatment is carried out, so that the organic matters in the mother liquor are thoroughly decomposed, the macromolecular substances which cannot be separated in the early stage are intercepted, and the content of the pollutants in the discharged wastewater is fully ensured to meet the national discharge standard. And moreover, low-temperature evaporation at 35-40 ℃ is adopted, so that energy consumption is saved, and the problems of adhesion and scaling of scales and organic matters on evaporation equipment due to overhigh temperature are solved.

By adopting the method, the high-difficulty dangerous waste liquid with the salt content of more than 20 percent and the COD concentration of more than 20 ten thousand ppm can be treated, and the medium-level dangerous waste liquid with the salt content of about 10 percent and the COD concentration of about 10 ten thousand ppm can also be treated; the method greatly concentrates, reduces and retreats the mother liquor by adopting low-temperature evaporation with lower energy consumption, and can overcome the problem of high cost of direct incineration treatment; the residue obtained after evaporation can be finally treated in a harmless way no matter the residue is incinerated or solidified and safely buried, and the method has the advantages of compact and reasonable design, small occupied area of equipment, low investment cost and low operation cost.

Preferably, the residue treatment system is an incineration treatment system, and the solid salt residues and the precipitates obtained in the steps S1 and S2 are incinerated to remove organic matters, so that harmless treatment is realized.

Preferably, the residue processing system is a solidification processing safety landfill system, and the solid salt residues and the sediments obtained in the steps S1 and S2 are packaged by ton bags and then conveyed to a rigid landfill site for safety landfill.

Preferably, step S1 employs a filtration method to separate the precipitate, which is less time and more thorough than the standing layering method.

the ozone generator is used for preparing ozone and conveying the ozone to the ozone catalytic oxidation reactor;

ozone catalytic oxidation reactor is equipped with ozone import, condensation evaporate import, tail gas export and ozone catalysis liquid export, and inside packing has the catalyst, and the filling rate is greater than 70%, and still is equipped with the micropore aerator in its inside for make ozone with less state evenly distributed, fully take place catalytic reaction with condensation evaporate, reaction production tail gas and ozone catalysis liquid, the tail gas is discharged and is carried to ozone tail gas destructor, handles the back and discharge. The ozone generator is convenient to use ozone, and the ozone tail gas can be treated by the ozone tail gas destructor to prevent secondary pollution.

Preferably, the membrane component adopts a 0.1 micron nanometer modified polyvinylidene fluoride (PVDF) flat membrane, and the modified PVDF has excellent chemical stability and thermal stability, and simultaneously has better water flux and separation effect, so that the method is suitable for treating the pesticide wastewater mother liquor containing high pollution and toxic substances.

Based on the method, the invention also provides a pesticide wastewater mother liquor treatment system, as shown in fig. 1, comprising a pretreatment regulation system, a low-temperature evaporation system 20, an ozone reaction system 30 and an MBR biochemical system 40 which are connected in sequence;

the pretreatment adjusting system is used for adjusting the pH value of the pesticide wastewater mother liquor to be alkalescent and accord with the discharge standard, the evaporation liquor of the next process is convenient to evaporate, the precipitate generated by pH adjustment is separated, insoluble particle suspended matters, grease and the like in water are removed to obtain the pretreatment mother liquor, and the pretreatment mother liquor is discharged and conveyed to the low-temperature evaporation system;

the low-temperature evaporation system 20 comprises an evaporation tank 22 and a condenser 24 which are sequentially connected, the evaporation tank is provided with a vacuum device 23, the vacuum degree of the evaporation tank can reach a set threshold value such as-95.5 to-93.7 kpa, the pretreated mother liquor is evaporated at a set low temperature such as 35 to 40 ℃, evaporated waste gas is discharged and conveyed to the condenser, condensed evaporation liquid is obtained after condensation by the condenser, and the condensed evaporation liquid is conveyed to an ozone reaction system; because the pretreatment is only pH neutralization adjustment treatment, a large amount of salt, toxic substances, organic substances and the like still remain in the pesticide wastewater mother liquor after the pretreatment, 90-95% of water contained in the mother liquor can be evaporated out under the conditions of-95.5 to-93.7 kpa and 35-40 ℃ through an evaporation box, the residual waste salt and high-boiling-point organic substances, namely the salt-containing slag concentrated solution, can be discharged and collected for recycling or harmless treatment, the evaporated waste gas is subjected to landfill treatment after the salt, part of the organic substances and other pollutants are removed, and the evaporated waste gas is condensed by a condenser and then enters subsequent treatment; and by setting vacuum of-95.5 to-93.7 kpa, steam can be formed at 35 to 40 ℃, 90 to 95 percent of water contained in the mother liquor is evaporated, so that the problems of energy consumption increased by steam formed at the temperature of more than 90 ℃ in conventional evaporation, and adhesion and scaling of water scales and organic matters on evaporation equipment due to overhigh temperature are avoided;

the ozone reaction system 30 comprises an ozone catalytic oxidation reactor 31, wherein a catalyst is filled in the ozone catalytic oxidation reactor and is used for enabling the condensed evaporated liquid to undergo an ozone catalytic reaction under the action of the catalyst to obtain an ozone catalytic liquid, and the ozone catalytic liquid is discharged and conveyed to an MBR biochemical system 40; after the pesticide wastewater mother liquor is pretreated and evaporated at low temperature, pollutants such as toxic substances, organic substances and the like are also remained, the toxic substances and the organic components are degraded by the catalytic reaction of an ozone reaction system, and the strong oxidizing property of ozone and the adsorption and catalytic properties of a catalyst are utilized, so that the toxic substances and the organic components are difficult to effectively treat the wastewater through biochemical reaction when the BOD/COD value in the wastewater is lower than 0.3, and the undegraded organic components in the wastewater subjected to low-temperature evaporation treatment can be further degraded through the catalytic oxidation reaction of the ozone, thereby improving the biodegradability of the wastewater and being beneficial to the subsequent biochemical treatment;

the MBR biochemical system 40 comprises an aerobic tank 41 and an MBR membrane bioreactor 42 positioned in the aerobic tank, and aerobic sludge is filled in the aerobic tank; a membrane module 43 is arranged in the MBR membrane bioreactor, and the aperture of a separation membrane on the membrane module 43 is less than or equal to 0.1 um; the MBR biochemical system is used for enabling ozone catalytic liquid to firstly enter an aerobic tank to react with aerobic sludge, then intercepting macromolecular substances through a membrane component of the membrane bioreactor, and obtaining purified wastewater which meets the discharge standard through solution which permeates the membrane component; after the treatment of the pretreatment regulating tank, the low-temperature evaporation system and the ozone reaction system, organic matters still remain in the pesticide wastewater mother liquor, the invention is combined with an MBR biochemical system for treatment, a Membrane Bioreactor (MBR) is used as a novel sewage treatment device, membrane separation and biological treatment technologies are organically combined, a secondary sedimentation tank in the traditional activated sludge process (CAS) is replaced, and the sludge-water separation efficiency is improved. Compared with the traditional CAS, the MBR has the advantages of good effluent quality, small occupied area, low sludge yield and the like, the pesticide wastewater mother liquor after the treatment is firstly treated with aerobic sludge in an aerobic tank to ensure that organic matters are sufficiently digested and degraded, and then enters the MBR membrane bioreactor, macromolecular substances are intercepted by a membrane component, pollutants such as suspended matters, bacteria, toxic substances and the like in water are further removed, and the effluent quality is ensured to meet the discharge standard.

Therefore, the invention combines a pretreatment regulating tank, a low-temperature evaporation system, an ozone reaction system and an MBR biochemical system, can treat high-difficulty dangerous waste liquid with salt content of more than 20 percent and COD concentration of more than 20 ten thousand ppm, and also can treat medium-level dangerous waste liquid with salt content of about 10 percent and COD concentration of about 10 ten thousand ppm, the whole system does not use any additional medicament except pH regulator, avoids the generation of additional waste, and the effluent can be directly discharged or recycled; the system of the invention adopts a low-temperature evaporation system with lower energy consumption to greatly concentrate, reduce and reprocess the mother liquor, and can overcome the problem of high cost of direct incineration treatment; the residue obtained after evaporation can be finally treated in a harmless way no matter the residue is incinerated or solidified and safely buried, and the system has compact and reasonable design, small floor area of equipment, low investment cost and low operation cost.

Preferably, the pretreatment regulating system comprises a pretreatment regulating tank 10 and a solid-liquid separation device 12, wherein the pretreatment regulating tank is provided with a pesticide wastewater mother liquor inlet, a pH regulator inlet and an outlet, and the outlet is connected with the solid-liquid separation device; the pesticide wastewater mother liquor enters the pretreatment regulating tank 10 through the pesticide wastewater mother liquor inlet, reacts with the pH regulator entering through the pH regulator inlet, is discharged through the outlet, is conveyed to a solid-liquid separation device, is separated and precipitated, and is discharged and conveyed to a low-temperature evaporation system. The solid-liquid separation device 12 is arranged, so that the precipitation separation of the mother liquor after the pH adjustment is convenient. The solid-liquid separation device is preferably a filter, the filter needs to be cleaned at regular time, and insoluble substances adhered on the filter are sent to an incineration plant for harmless disposal.

Preferably, the low temperature evaporation system 20 further comprises a heat exchanger 21 connected to the evaporation tank; the pre-treatment mother liquor firstly passes through the heat exchanger 21, exchanges heat and then enters the evaporation box 22 for low-temperature evaporation, so that the energy consumption is saved.

Preferably, the ozone reaction system 30 further comprises an ozone generator 33 connected to the ozone catalytic oxidation reactor 31, and an ozone off-gas destructor 32;

the ozone generator 33 is used for preparing ozone and conveying the ozone to the ozone catalytic oxidation reactor 31;

ozone catalytic oxidation reactor 32 is equipped with ozone import, condensation evaporate import, tail gas export and ozone catalysis liquid export, and inside packing has the catalyst, and the filling rate is greater than 70%, and still is equipped with micropore aerator 34 in its inside for make ozone with less state evenly distributed, fully take place catalytic reaction with condensation evaporate, the reaction produces tail gas and ozone catalysis liquid, and the tail gas is discharged and is carried to ozone tail gas destructor, discharges after the processing.

The ozone generator 33 is arranged, so that the ozone is convenient to use, and the ozone tail gas can be treated by the ozone tail gas destructor 32, so that secondary pollution is prevented.

Preferably, the ozone inlet and the condensed evaporation liquid inlet are positioned at the bottom of the ozone catalytic oxidation reactor 31, the tail gas outlet and the ozone catalytic liquid outlet are positioned at the top of the ozone catalytic oxidation reactor 31, the condensed evaporation liquid and the ozone enter from the bottom of the ozone catalytic oxidation reactor, and are discharged from the top, so that the condensed evaporation liquid and the ozone can be fully contacted with microorganisms and membrane components, and the treatment effect is improved.

Preferably, the system further comprises an adjusting tank 50, two ends of the adjusting tank are respectively connected with the ozone reaction system and the MBR biochemical system, the ozone catalytic liquid enters the MBR biochemical system after being adjusted by the adjusting tank, and the stability of the water quality and the water quantity of the water source entering the MBR system is ensured by arranging the adjusting tank.

Preferably, the membrane bioreactor also comprises a box body and an aeration system 42, the membrane module and the aeration system are both positioned in the box body, the aeration system is positioned below the membrane module, and the aeration system can provide oxygen required by aerobic reaction and can also wash the membrane module through airflow so as to reduce pollution of the membrane module.

Example 1

The waste salt of the mother liquor of the waste water of a pesticide manufacturing workshop in Shandong, which has 17 percent of waste salt and 12.5 ten thousand ppm of COD, is treated by the system shown in figure 1, and the specific steps are as follows:

s1, pretreatment: conveying the mother liquor into a pretreatment regulating reservoir, arranging a filter at an outlet of the pretreatment regulating reservoir, regulating the pH value of the pesticide wastewater mother liquor to 8.0 by using sodium hydroxide, conveying the mother liquor to the filter, filtering, separating and precipitating, and lifting the clear liquor (namely the pretreatment mother liquor) to a heat exchanger of a low-temperature evaporation system by using a lifting pump;

s2, low-temperature evaporation: after passing through a heat exchanger, heating the pretreated mother liquor to 40 ℃, then feeding the pretreated mother liquor into an evaporation tank, adjusting the vacuum degree of the evaporation tank to-95.5 to-93.7 kpa, adjusting the temperature to 35 to 40 ℃, evaporating 90 to 95 percent of water contained in the mother liquor at a low temperature, condensing evaporated waste gas to obtain condensed evaporation liquor, discharging the salt-containing slag concentrated liquor from the bottom of the evaporation tank, performing filter pressing separation, collecting and conveying the separated solid salt slag and the precipitate obtained in the step S1 to an incineration system in a centralized manner, and removing organic matters after incineration to realize harmless treatment; the separated liquid is circulated to the step S1 to repeat the treatment;

s3, ozone reaction: ozone is prepared by an ozone reaction system, and the prepared ozone is controlled by a gas flowmeter to enter a catalytic oxidation reactor to participate in reaction. Ozone gas enters from the bottom of the catalytic oxidation reactor, and a microporous aerator is arranged at the bottom of the reactor, so that the ozone gas is uniformly distributed in a small form and fully reacts. The reactor was filled with a catalyst at a filling rate of 70%. The condensed evaporation liquid enters from the bottom of the catalytic oxidation reactor, and is discharged from the top of the catalytic oxidation reactor to enter into a regulating tank. The tail gas of ozone generated in the reaction process is treated by a tail gas destructor and then is discharged into the air;

and S4, adjusting the water quality and the water quantity of the ozone catalytic liquid obtained in the step S3, then feeding the ozone catalytic liquid into an aerobic tank, and after the ozone catalytic liquid reacts with aerobic sludge in the aerobic tank, filtering produced water by an MBR membrane bioreactor membrane module and then discharging the filtered produced water.

Through measurement, TDS in the condensed evaporation liquid treated by the low-temperature evaporation system is reduced to 147ppm, COD is reduced to 900ppm, and BOD/COD value is 0.19; the TDS value in the ozone catalytic evaporation liquid is reduced to 141ppm, the COD content is reduced to 693ppm, the BOD/COD value is 0.59, the biodegradability is obviously enhanced, the TDS content is reduced to 120ppm after the treatment of the MBR membrane bioreactor, and the COD content is reduced to 23ppm, which indicates that organic matters (including toxic substances) in the wastewater are completely degraded, accords with the national discharge standard, and can be directly discharged or recycled.

Example 2

The method comprises the following steps of treating 22% of waste salt and 43 ppm of COD in a mother liquor of pesticide manufacturing workshop in Hebei with a system shown in figure 1:

s2, low-temperature evaporation: after passing through a heat exchanger, heating the pretreated mother liquor to 40 ℃, then feeding the pretreated mother liquor into an evaporation tank, adjusting the vacuum degree of the evaporation tank to-95.5 to-93.7 kpa, adjusting the temperature to 35 to 40 ℃, evaporating 90 to 95 percent of water contained in the mother liquor at a low temperature, condensing evaporated waste gas to obtain condensed evaporation liquor, discharging waste salt of the salt-containing slag concentrated liquor from the bottom of the evaporation tank, performing filter pressing separation, conveying the separated solid salt slag and the precipitate obtained in the step S1 to an incineration treatment system, and removing organic matters after incineration to realize harmless treatment; the separated liquid is circulated to the step S1 to repeat the treatment;

and S4, adjusting the water quality and the water quantity of the ozone catalytic liquid obtained in the step S3, then feeding the ozone catalytic liquid into an aerobic tank, and after the ozone catalytic liquid reacts with aerobic sludge, filtering produced water by an MBR membrane bioreactor membrane module and then discharging the filtered produced water.

Through determination, the TDS value of the condensed evaporation liquid treated by the low-temperature evaporation system is 269ppm, the COD value is 2300ppm, and the BOD/COD value is 0.07; the COD content in the ozone catalytic liquid is 1760ppm, the BOD/COD value is 0.51, the biodegradability is obviously improved, the COD content is reduced to 49ppm after the treatment of the MBR membrane bioreactor, the national emission standard is met, and the ozone catalytic liquid can be directly discharged or recycled.

As will be appreciated by those skilled in the art, the method and system disclosed herein are not limited to the treatment of pesticide wastewater mother liquor, but may be applied to other MVR evaporation mother liquor or high salt, high organic matter, and difficult biochemical waste liquor.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

Claims

1. The method for treating the pesticide wastewater mother liquor is characterized by comprising the following steps of:

s2, low-temperature evaporation: carrying out low-temperature evaporation on the pretreated mother liquor obtained in the step S1 through a low-temperature evaporation system at the temperature of-95.5 to-93.7 kpa and at the temperature of 35 to 40 ℃ to obtain salt slag-containing concentrated liquor and evaporation waste gas, and condensing the evaporation waste gas to obtain condensed evaporation liquor;

s5, performing filter pressing separation on the salt-containing slag concentrated solution obtained in the step S2, returning the separated liquid to S1 for continuous treatment, and conveying the separated solid salt slag and the precipitate obtained by precipitation in the step S1 to a residue treatment system together.

2. The method for treating pesticide wastewater mother liquor according to claim 1, wherein the residue treatment system is an incineration treatment system, and the solid salt residue and the precipitate are incinerated to remove organic matters, thereby realizing harmless treatment.

3. The method for treating pesticide wastewater mother liquor as claimed in claim 1, wherein the residue treatment system is a safe landfill system, and the solid salt residue and the precipitate are packaged by ton bags and then transported to a rigid landfill for safe landfill.

4. The method for treating a mother liquor of agricultural chemical waste water according to claim 1,

and step S1, adjusting the pH value of the pesticide wastewater mother liquor by using sodium hydroxide.

5. The method for treating a mother liquor of agricultural chemical waste water according to claim 1,

step S3, the ozone reaction system comprises an ozone generator, an ozone catalytic oxidation reactor and an ozone tail gas destructor which are connected in sequence;

the ozone catalytic oxidation reactor is provided with an ozone inlet, a condensed evaporative liquid inlet, a tail gas outlet and an ozone catalytic liquid outlet, the catalyst is filled in the ozone catalytic oxidation reactor, the filling rate is more than 70%, the ozone catalytic oxidation reactor is also provided with a micropore aerator in the ozone catalytic oxidation reactor, the micropore aerator is used for enabling ozone to be uniformly distributed in a small state and to perform catalytic reaction with the condensed evaporative liquid, tail gas and the ozone catalytic liquid are generated through reaction, the tail gas is discharged and conveyed to the ozone tail gas destructor, and the tail gas is discharged after treatment.

6. A treatment system for pesticide wastewater mother liquor is characterized by comprising a pretreatment system, a low-temperature evaporation system, an ozone reaction system and an MBR biochemical system which are sequentially connected;

the MBR biochemical system comprises an aerobic tank and an MBR membrane bioreactor positioned in the aerobic tank, and aerobic sludge is filled in the aerobic tank; a membrane module is arranged in the MBR membrane bioreactor, and the aperture of a separation membrane on the membrane module is less than or equal to 0.1 um; the MBR biochemical system is used for enabling the ozone catalytic liquid to firstly enter the aerobic tank to react with the aerobic sludge, and then intercepting macromolecular substances through a membrane module of the membrane bioreactor, wherein the solution penetrating through the membrane module is purified wastewater meeting the discharge standard;

preferably, the treatment system further comprises an adjusting tank, two ends of the adjusting tank are respectively connected with the ozone reaction system and the MBR biochemical system, and the ozone catalytic liquid enters the MBR biochemical system after being adjusted by the adjusting tank; alternatively, the first and second electrodes may be,

preferably, the membrane bioreactor further comprises a box body and an aeration system, the membrane module and the aeration system are both positioned in the box body, and the aeration system is positioned below the membrane module.

7. The system for treating a mother liquor of agricultural chemical wastewater according to claim 6,

the pretreatment regulating system comprises a pretreatment regulating reservoir and a solid-liquid separation device, wherein the pretreatment regulating reservoir is provided with a pesticide wastewater mother liquor inlet, a pH regulator inlet and an outlet, and the outlet is connected with the solid-liquid separation device;

the pesticide wastewater mother liquor enters the pretreatment regulating tank through the pesticide wastewater mother liquor inlet, reacts with the pH regulator entering through the pH regulator inlet, is discharged through the outlet and conveyed to the solid-liquid separation device, and after separation and precipitation, clear liquid is discharged and conveyed to the low-temperature evaporation system.

8. The system for treating a mother liquor of agricultural chemical wastewater according to claim 6,

the low-temperature evaporation system also comprises a heat exchanger connected with the evaporation tank;

the pretreatment mother liquor firstly passes through the heat exchanger, exchanges heat and then enters the evaporation tank.

9. The system for treating a mother liquor of agricultural chemical wastewater according to claim 6,

the ozone reaction system also comprises an ozone generator and an ozone tail gas destructor which are connected with the ozone catalytic oxidation reactor;

10. The system for treating a mother liquor of agricultural chemical wastewater according to claim 9,

the ozone inlet and the condensed evaporation liquid inlet are positioned at the bottom of the ozone catalytic oxidation reactor, and the tail gas outlet and the ozone catalytic liquid outlet are positioned at the top of the ozone catalytic oxidation reactor.