Pretreatment process of pesticide chemical sewage containing processing and packaging

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a pretreatment process of pesticide chemical wastewater containing processing and packaging. The process adopts a core thought of demulsification, iron-carbon micro-electrolysis and heterogeneous fluidized bed catalytic oxidation to solve the problems of complex components, high toxicity, high-concentration emulsified oil content, poor biodegradability and large incoming water fluctuation of pesticide wastewater. The method comprises the following steps: separately carrying out demulsification treatment on processing and packaging wastewater rich in an emulsifier, mixing the demulsified wastewater with other pesticide production wastewater, and sequentially carrying out an iron-carbon micro-electrolysis reaction and a heterogeneous fluidized bed catalytic oxidation reaction. Through the multi-stage synergistic effect, emulsified oil is effectively cracked, macromolecular toxic refractory organic matters (such as organochlorine and organophosphorus) are degraded, the biodegradability of the wastewater is remarkably improved (the B / C ratio is 0.3 or above), the COD load is reduced (the removal rate is 30% or above), good conditions are created for subsequent biochemical treatment, and the technical problems that the wastewater treatment cost is high and the standard reaching is difficult are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of pre-treatment process of pesticide chemical industrial wastewater containing processing package, belong to wastewater treatment technical field. BACKGROUND

[0002] As an important measure to ensure the quality of crops, the product types of pesticides are constantly upgraded, and the raw materials used are also constantly changed and increased. The wastewater discharged during pesticide production is complex in composition and highly toxic. It contains various toxic and difficult-to-degrade organic or inorganic substances such as organic nitrogen, organic chlorine and organic phosphorus, and has characteristics such as high salt content and high chloride ion, resulting in extremely poor biodegradability and extremely low BC ratio, making it extremely difficult to be directly biologically treated. In addition, the processing and packaging wastewater mixed by pesticide enterprises also contains a large amount of surfactants and emulsifiers, and high-concentration emulsified oils, forming a stable oil-water mixture, further increasing the difficulty of wastewater treatment. Therefore, the cost of the entire treatment process is higher, and it is more difficult to meet the standard for discharge. Therefore, the pre-treatment of pesticide chemical industrial wastewater containing packaging is becoming increasingly difficult.

[0003] With the increasingly stringent wastewater discharge standards and the increasing cost of wastewater treatment, the pre-treatment of such pesticide wastewater, which is complex in composition, highly toxic, contains high-concentration emulsified oils and has poor biodegradability, has certain research significance. In view of the increasingly stringent environmental protection discharge standards and the high cost of wastewater treatment, it is of great importance to develop an efficient, economical and stable pre-treatment process for the standard discharge and reuse of such pesticide chemical wastewater.

[0004] Traditional pre-treatment methods such as single coagulation sedimentation, Fenton oxidation and ozone oxidation have problems such as unstable treatment effect, high operating cost and generation of a large amount of iron sludge secondary pollution. Ozone oxidation consumes a large amount of electricity and is accompanied by ozone leakage pollution. Patent CN109704510A describes the advantages of heterogeneous fluidized bed catalytic oxidation over Fenton. At the same time, taking advantage of the acidic characteristics of the effluent from iron-carbon microelectrolysis, the acid adjustment part of heterogeneous fluidized bed catalytic oxidation is omitted, the amount of acid used is reduced, the corresponding equipment investment is reduced, the amount of alkali used for pH adjustment in the microelectrolysis process is also reduced, and the corresponding equipment investment is also reduced. The same simple process also reduces the cost of chemicals. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide an efficient and stable pre-treatment process for pesticide chemical industrial wastewater containing processing package. This process effectively breaks down emulsified oil, degrades toxic pollutants and significantly improves the biodegradability of wastewater through targeted and hierarchical treatment, laying a solid foundation for subsequent low-cost biological treatment of pesticide chemical industrial wastewater containing processing package.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A pretreatment process of pesticide chemical industrial wastewater containing processing packaging, specifically comprising the following steps:

[0008] S1, demulsification: the processing packaging wastewater is collected separately into a conditioning tank. A demulsifier is added to the tank, and the pH is controlled to be below 10, and the reaction is stirred. Then the water is introduced into a sedimentation tank reaction tank, a flocculant PAC is added, and after stirring reaction, a coagulant aid PAM is added, and after slow stirring, it enters the sedimentation tank for solid-liquid separation.

[0009] S2, iron-carbon micro-electrolysis reaction: the supernatant effluent of the S1 sedimentation tank is mixed with the main pesticide production wastewater in a mixing conditioning tank. After adjusting the pH of the mixed wastewater with acid, it is pumped into an iron-carbon micro-electrolysis reaction tank. The iron-carbon micro-electrolysis reaction tank is filled with iron-carbon filler, and is accompanied by aeration reaction time.

[0010] S3, heterogeneous fluidized bed catalytic oxidation reaction: the effluent of S2 is pumped into a heterogeneous fluidized bed catalytic oxidation tower. The tower is filled with granular catalyst. An oxidizing agent hydrogen peroxide (H2O2) is added to the tower, and the dosage is determined according to the COD value of the influent, and the H2O2 dosage is 1g / L-1.8g / L. The reaction time is controlled within 0.5-2 hours, the effluent is adjusted to pH 6-9, and a coagulant aid PAM (dosage 2-10mg / L) is added, and after sedimentation in a sedimentation tank for 0.5-2 hours, it enters the biochemical reaction stage. The COD removal rate is >30%, and the B / C ratio of the effluent can be increased from less than 0.1 to more than 0.3.

[0011] According to the present application, preferably, in step S1, demulsification, the processing packaging wastewater accounts for about 1%-20% of the total amount of wastewater.

[0012] According to the present application, preferably, in step S1, demulsification, the demulsifier is one of lime, sodium hydroxide, potassium chloride, and sodium chloride, or a combination of two, the dosage of the demulsifier is 100-600mg / L, the pH value is controlled to be not higher than 10, and the stirring reaction time is 20-40 minutes.

[0013] According to the present application, preferably, in step S1, demulsification, the dosage of the flocculant PAC is 100-500mg / L, and the stirring reaction time is 10-20 minutes.

[0014] According to the present application, preferably, in step S1, demulsification, the dosage of the coagulant aid PAM is 5-20mg / L, and the slow stirring time is 10-30 minutes.

[0015] S1, demulsification, the core of this step is to break the stable emulsion system, separate out oil and part of suspended solids, and avoid affecting the subsequent advanced oxidation efficiency.

[0016] According to the present application, preferably, in step S2, iron-carbon micro-electrolysis reaction, the pH of the mixed wastewater is adjusted to 2-4 with acid.

[0017] According to the application, preferably, in step S2, the iron-carbon micro-electrolysis reaction, the iron-carbon micro-electrolysis reaction tank is filled with iron-carbon filler cast iron chips and activated carbon (mass ratio 1:1 to 3:1), and is accompanied by aeration (air-water ratio 5:1 to 15:1), and the reaction time is 1-3 hours.

[0018] In step S2, the iron-carbon micro-electrolysis reaction, under the condition of acid and oxygen, iron and carbon form countless micro-batteries, generate strong reducing power of nascent hydrogen and ferrous ions, can effectively break the chemical bonds of macromolecular refractory organic matter (such as halogenated hydrocarbons, nitro compounds) in wastewater, make it into small molecular organic matter, at the same time realize partial oxidation and coagulation and sedimentation.

[0019] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the tower is filled with granular catalyst loaded with Cu, Mn, Fe and other transition metals.

[0020] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the oxidant hydrogen peroxide (H2O2), the dosage is determined according to the COD value of the influent, and the dosage of H2O2 is 1g / L-1.8g / L.

[0021] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the reaction time is 0.5-2 hours.

[0022] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the effluent is adjusted to pH 6-9.

[0023] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the coagulant PAM dosage is 2-10mg / L.

[0024] According to the application, preferably, in step S3, the heterogeneous fluidized bed catalytic oxidation reaction, the sedimentation tank sedimentation residence time is 0.5-2 hours.

[0025] In step S3, the heterogeneous fluidized bed catalytic oxidation reaction, under the action of the catalyst, H2O2 is catalytically decomposed to produce hydroxyl radicals with strong oxidizing ability, these radicals can attack and completely degrade the organic matter in wastewater without selectivity, and finally oxidize it into CO2, H2O or small molecular organic acid, effectively remove the refractory COD, thereby greatly improving the B / C ratio of the wastewater.

[0026] The COD removal rate of the pesticide chemical wastewater containing processing and packaging is more than 30% after demulsification, iron-carbon micro-electrolysis reaction and heterogeneous fluidized bed catalytic oxidation reaction, and the B / C ratio of the effluent can be increased from less than 0.1 to more than 0.3. The process is an efficient, economical and stable pretreatment process, which can effectively break emulsified oil, degrade toxic pollutants and significantly improve the biodegradability of wastewater, thereby laying a solid foundation for subsequent low-cost biochemical treatment. The process is crucial for the standard discharge and reuse of such pesticide chemical wastewater.

[0027] The beneficial effects of the present application are as follows:

[0028] 1. The treatment process of the present application is highly targeted and synergistic: innovatively, the most difficult processing and packaging wastewater is separately subjected to demulsification pretreatment, thereby avoiding the interference and damage of a large amount of emulsifiers and emulsified oil in the processing and packaging wastewater to the subsequent core oxidation unit. Subsequently, iron-carbon micro-electrolysis and heterogeneous catalytic oxidation form perfect connection, the former is mainly for reduction and chain breaking, and the latter is mainly for deep oxidation, the two stages are synergistic, which significantly improves the overall removal efficiency of toxic pollutants in the pesticide chemical wastewater, and the process is synergistic and efficient, while saving the amount of acid used in the heterogeneous fluidized bed catalytic oxidation reaction and the corresponding equipment investment.

[0029] 2. The biodegradability of the wastewater treated by the treatment process of the present application is significantly improved: the core advantage of the present process is that the difficult-to-biodegrade pollutants in the pesticide chemical wastewater are converted into easily-biodegradable substances, the B / C ratio of the effluent can be increased from less than 0.1 to more than 0.3, which greatly reduces the burden and cost of subsequent biochemical treatment, and ensures the stable operation and standard discharge of the entire treatment system.

[0030] 3. The treatment process of the present application has relatively low operating cost: compared with the traditional Fenton method, the solid catalyst used in the heterogeneous catalytic oxidation technology can be reused for a long time, which reduces the consumption of ferrous and other reagents, and does not produce a large amount of iron-containing sludge, thereby reducing the sludge disposal cost and saving the investment in acid adjustment and acid adjustment equipment. The entire treatment process effectively degrades COD, reduces the pressure and cost of subsequent treatment, and also reduces the overall treatment cost of wastewater discharge.

[0031] 4. The treatment process of the present application has stable and reliable treatment effect: the process has strong resistance to impact load, and has good adaptability to the wastewater with large fluctuations in water quality and quantity from multiple water sources through the pretreatment process, and the treated effluent has stable quality. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The process flow chart of the present application is shown in the figure. DETAILED DESCRIPTION

[0033] The application will be further described below in connection with specific embodiments, but the scope of the application is not limited thereto. The technical solutions in the embodiments of the application will be described clearly and completely below in connection with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the application.

[0034] Example 1

[0035] The wastewater of a pesticide chemical plant in Anhui mainly produces insecticides, and the wastewater contains production wastewater and packaging wastewater of multiple product workshops. The original mixed wastewater has a COD of about 31000-33000 mg / L, a BOD5 of about 2700 mg / L (B / C≤0.08), a chloride ion concentration of about 20000 mg / L, and packaging wastewater (COD 14000-15000 mg / L).

[0036] The packaging wastewater is treated separately, and then mixed with other water after treatment.

[0037] S1: Take 200 parts of packaging wastewater (COD packaging wastewater (COD=15000 mg / L) 15000 mg / L), add demulsifier 400 mg / L to make pH 9, and quickly stir for 20 minutes. Then, PAC (400 mg / L) is added, and quickly stirred for 20 minutes. Then, PAM (10 mg / L) is added, and slowly stirred for 10 minutes. Then, the mixture is fed into a sedimentation tank for solid-liquid separation. The core of this step is to break the stable emulsion system, separate out oil and part of suspended solids, and avoid affecting the subsequent efficiency of advanced oxidation. The COD of the supernatant is reduced to ≤10000 mg / L, and the petroleum is reduced to below 80 mg / L.

[0038] S2: The supernatant of S1 is mixed with 1800 parts of production wastewater. The pH of the mixed water sample is adjusted to 3 with sulfuric acid, and then pumped into an iron-carbon micro-electrolysis cell (iron-carbon ratio 2:1). The mixture is aerated (air-water ratio 10:1) for 2 hours.

[0039] S3: The effluent of S2 is directly pumped into a fluidized bed catalytic oxidation tower (catalyst is a catalyst particle loaded with ferric oxide), and hydrogen peroxide is added. The dosage of hydrogen peroxide is 1.6 g / L. After 1 hour of reaction, the pH is adjusted to 6-9, and the coagulant PAM is added at a dosage of 4 mg / L. The mixture is fed into a sedimentation tank for sedimentation, and the residence time is 1 hour.

[0040] Results: The final effluent has a COD of about 21000 mg / L, a total COD removal rate of about 34%, a BOD5 of about 6700 mg / L, and a B / C ratio of 0.32. The final effluent is fed into a contact oxidation tank for biochemical reaction.

[0041] Example 2

[0042] The packaging wastewater is not subjected to demulsification and is directly mixed with other water streams.

[0043] S1: 200 parts of packaging wastewater is subjected to flow.

[0044] S2: The water from S1 is mixed with 1800 parts of production wastewater. The pH of the mixed water sample is adjusted to 3 with sulfuric acid, and the mixture is pumped into an iron-carbon micro-electrolysis cell (iron-carbon ratio 2:1), aerated (air-water ratio 10:1) and reacted for 2 hours.

[0045] S3: The water from S2 is directly pumped into a fluidized bed catalytic oxidation tower (catalyst is a catalyst particle loaded with ferric oxide), hydrogen peroxide is added, the amount of hydrogen peroxide is 1.6 g / L, the reaction is carried out for 1 hour, the pH is adjusted to 6-9, and the coagulant PAM is added at a dosage of 4 mg / L. The mixture is then introduced into a sedimentation tank for sedimentation, and the residence time is 1 hour.

[0046] Results: The COD of the final effluent is about 23000 mg / L, the total COD removal rate is about 28%, the BOD5 is about 5600 mg / L, and the B / C ratio is increased to 0.24. The effluent is introduced into a contact oxidation tank for biochemical reaction.

[0047] Comparative Example

[0048] The raw water is a mixture of production wastewater and packaging wastewater from each workshop, with a COD of about 31000-33000 mg / L, a BOD5 of about 2700 mg / L (B / C≤0.08), a chloride ion concentration of about 20000 mg / L, and a packaging wastewater (COD 14000-15000 mg / L).

[0049] After treatment according to Example 1, the COD of the effluent is about 21000 mg / L, the total COD removal rate is about 34%, the BOD5 is about 6700 mg / L, the B / C ratio is increased to 0.32, and the effluent has obvious biodegradability. After treatment according to Example 2, the COD of the effluent is about 23000 mg / L, the total COD removal rate is about 28%, the BOD5 is about 5600 mg / L, the B / C ratio is increased to 0.24, and the biodegradability is also significantly improved. Comparison of Example 1 and Example 2 shows that after S1 demulsification treatment, the COD removal rate of the effluent is increased, and the biodegradability is significantly improved.

[0050] Example 3

[0051] Stable process treatment effect verification

[0052] The experiment of embodiment 1 is continuously operated, and due to the daily production situation and process change of each workshop product, the water quality and quantity of the incoming water fluctuate every day, the COD of the incoming water is about 31000-33000 mg / L, the BOD5 is about 2600-2700 mg / L, the packaging wastewater (COD 14000-15000 mg / L) treatment data is stable, and the effluent COD is maintained at 20000-23000 mg / L, and the BOD5 is about 64000-6800 mg / L.

[0053] The treatment effect of the treatment process of the application is stable and reliable after continuous operation, the set of processes has strong resistance to production incoming water impact load capacity, and the pretreatment process has good adaptability to the large water quality and quantity fluctuation of the pesticide wastewater, and the treated effluent water quality is stable.

[0054] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A pretreatment process for pesticide and chemical wastewater including processing and packaging, characterized in that, Includes the following steps: S1, Demulsification: Collect the processing and packaging wastewater separately into the equalization tank, add demulsifier to the tank, control its pH to below 10, stir and react, introduce the water into the sedimentation tank reaction tank, add flocculant PAC, stir and react, and then slowly stir the coagulant aid PAM before entering the sedimentation tank for solid-liquid separation. S2, Iron-Carbon Micro-Electrolysis Reaction: The supernatant effluent from the S1 sedimentation tank is thoroughly mixed with the main pesticide production wastewater in a mixing and conditioning tank. After adjusting the pH value of the mixed wastewater to 2-4 with acid, it is pumped into the iron-carbon micro-electrolysis reaction tank. The reactor is filled with cast iron filings and activated carbon, and aeration is carried out. The reaction time is 1-3 hours. S3, heterogeneous fluidized bed catalytic oxidation reaction: The effluent from S2 is pumped into a heterogeneous fluidized bed catalytic oxidation tower, which is filled with granular catalyst. Hydrogen peroxide (H2O2) is added to the tower as an oxidant. The reaction time is controlled at 1-2 hours. After the effluent is aerated and the pH is adjusted to 6-9, PAM coagulant is added. After sedimentation in a sedimentation tank, the effluent enters the biochemical reaction stage.

2. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, In step S1, the demulsifier is one or a mixture of two of lime, sodium hydroxide, potassium chloride, and sodium chloride; the pH value of the demulsification reaction is adjusted not to be higher than 10, the reaction time is 20-40 minutes, the dosage of flocculant PAC is 100-500 mg / L, the reaction is stirred for 10-20 minutes, and then the dosage of coagulant aid PAM is added at 5-20 mg / L, and the mixture is stirred slowly for 10-30 minutes.

3. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, In step S2, the conditions for the iron-carbon micro-electrolysis reaction are: iron-carbon mass ratio of (1:1)-(3:1), reaction pH value of 2-4, reaction time of 1-3 hours, and aeration rate of air-to-water ratio of (5:1)-(15:1).

4. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, In step S3, the conditions for the heterogeneous fluidized bed catalytic oxidation reaction are as follows: the column is filled with granular catalyst loaded with Cu, Mn and Fe transition metals, hydrogen peroxide (H2O2) is used as the oxidant, the H2O2 dosage is 1g / L-1.8g / L, and the reaction time is 0.5-2 hours.

5. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, Step S3: Heterogeneous fluidized bed catalytic oxidation reaction, effluent pH adjusted to 6-9, PAM coagulant dosage 2-10 mg / L, enters sedimentation tank for sedimentation, retention time 0.5-2 hours.

6. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, The influent COD is 31000-33000 mg / L and BOD5 is less than 2700 mg / L. The treatment data for packaging wastewater (COD 14000-15000 mg / L) shows that the effluent COD remains at 20000-23000 mg / L and BOD5 at 64000-6800 mg / L. Processing and packaging wastewater accounts for approximately 1%-20% of the total wastewater.

7. The pretreatment process for pesticide and chemical wastewater containing processing and packaging materials according to claim 1, characterized in that, After pretreatment steps S1, S2, and S3, the B / C ratio of the effluent increased from less than 0.1 to greater than 0.3, and the total COD removal rate reached over 30%.

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