Treatment method for chemical cleaning waste liquid of water treatment filtering membrane

Abstract

The invention discloses a treatment method of chemical washing waste liquid of a water treatment filter membrane, the chemical washing waste liquid comprises acid washing waste liquid and alkali washing waste liquid, and the treatment method comprises the following steps: S1, mixing the acid washing waste liquid and the alkali washing waste liquid until the pH value of the obtained mixed liquid is 2-5, adding a catalyst and an oxidizing agent, and carrying out a catalytic oxidation reaction; s2, after the catalytic oxidation reaction, alkali washing waste liquid is injected into the mixed liquid for pH adjustment, so that the pH value of the mixed liquid is neutral or slightly alkaline, and a flocculation reaction is carried out; and S3, after the flocculation reaction, adding a hardness removal agent for hardness removal, and performing organic matter adsorption by an adsorbent. According to the method disclosed by the invention, the pickling waste liquid and the alkali washing waste liquid with high organic pollution are mixed in different proportions in different reaction stages to create catalytic reaction conditions required by Fenton (class), so that the process defect that neutralization is performed firstly and then acid and alkali are added for regulation is avoided, and the conditions required by Fenton (class) oxidation are met; and the problem of high acid and alkali consumption in the (similar) Fenton oxidation process is avoided.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to a method for treating waste liquid from chemical cleaning of a water treatment filter membrane. Background Art

[0002] As a new water treatment industry module in recent decades, membrane filtration technology has seen a sharp expansion in application scale in recent years due to the advancement of membrane materials, high treatment efficiency, and gradually reduced costs. Developed countries developed and applied membrane technology earlier than my country, and have established a system covering all major membrane process products. The maturity of membrane products and technology applications is also relatively high. At the same time, they are still keeping up with market demand and continuously developing and applying some new membrane materials and membrane products to further expand their market share. The domestic market is also keeping pace, and it is expected that the market size will reach 361 billion yuan in 2022.

[0003] Membrane technology is mainly used in the water treatment industry in the fields of domestic sewage treatment, industrial wastewater treatment and reuse, seawater desalination, and ultrapure water preparation. In recent years, with the increasing improvement of environmental protection standards and the zero-emission requirements of specific industries, membrane filtration has an absolute advantage in the treatment of high-salinity wastewater. Therefore, membrane combined treatment systems with reverse osmosis as the core and ultrafiltration and nanofiltration as the auxiliary are increasingly widely used in the field of industrial wastewater treatment.

[0004] However, during the operation of the membrane, as the operation cycle is prolonged, it is inevitable that a calcium and magnesium scaling layer, organic fouling, and microbial growth will form on the membrane surface, reducing membrane flux and deteriorating effluent quality. Therefore, water washing and chemical cleaning are required from time to time, especially for zero-discharge systems for industrial wastewater. Because the concentration of pollutants in the incoming water is high and the water quality is relatively poor, conventional pretreatment has limited effect. Compared with the use of membrane methods for ultrapure water preparation, in zero-discharge systems for industrial wastewater treatment, some difficult-to-degrade organic matter and salts in the system will eventually enter the membrane filtration link. Therefore, the membrane operation cycle is significantly shortened, and sometimes the system needs to be shut down for chemical backwashing after running for 2 to 7 days. Therefore, the amount of membrane washing waste liquid generated is significantly more than that in membrane application scenarios such as ultrapure water preparation, and it is strongly acidic or alkaline, with a high salt content and a high concentration of organic pollutants.

[0005] The early application scenarios of membrane filtration were mainly used for seawater desalination, ultrapure water preparation, etc. Because the water quality was good and the operation cycle was relatively long, and the degree of membrane surface contamination was low, a very small amount of chemical backwash liquid generally re-entered the membrane front-end pretreatment coagulation-sedimentation link to remove suspended matter and hardness, and then flowed into the membrane treatment system. However, with the development of the market, the application scenarios have expanded to zero discharge of industrial wastewater. For example, in the treatment of highly polluted wastewater from coal chemical industry, the double membrane cleaning liquid is also "conservative" and the membrane washing waste liquid flows into the membrane front-end pretreatment system nearby and re-enters the membrane treatment unit.

[0006] Sampling of chemical membrane washing waste liquid from some coal chemical zero emission treatment systems showed that the COD of ultrafiltration acid washing, ultrafiltration alkaline washing, reverse osmosis acid washing and reverse osmosis alkaline washing water samples was generally between 1000 and 2000 mg / L, the conductivity was >20 mS / cm, the salt content was high, and the membrane washing process often used strong acids, strong alkalis, chelating agents EDTA, bactericides and composite eluents, etc., which significantly improved the membrane washing effect. However, the secondary treatment of the waste liquid generated by membrane washing has been seriously neglected. Therefore, although the highly polluted and difficult to treat membrane washing wastewater is small in volume, it brings about serious secondary pollution problems.

[0007] In addition, the calcium ions eluted by adding the complexing agent basically exist in the form of complex (EDTA-Ca). The complex calcium ions return to the chemical hardness removal process in the pretreatment link without any removal effect, and then flow into the membrane unit again. The complex calcium ions and organic matter and the breeding microorganisms are very easy to form various forms of composite pollution on the membrane surface, causing the membrane flux to decrease or even damage the membrane. Therefore, it is very important to economically and effectively reduce the COD of the highly polluted and small-volume chemical membrane washing wastewater and remove the complex hardness for the efficient operation of the zero-emission system.

[0008] Advanced oxidation technology is a pretreatment and deep treatment technology that has developed rapidly in recent years. The hydroxyl free radicals it produces have strong oxidative activity and have unique advantages for high-organic pollutant and difficult-to-degrade wastewater. In particular, the (quasi) Fenton oxidation treatment method has been widely used due to its high oxidation efficiency, no need for large-scale equipment, and low treatment cost. However, one of its major constraints is that the required reaction environment is an acidic system. Therefore, in order to meet its reaction conditions, the water must first be adjusted to acidic, and then adjusted to neutral with alkali after the reaction to meet the biochemical treatment or effluent requirements. Therefore, this process causes a large amount of acid and alkali consumption, and introduces salts into the water, which has become a major problem restricting the application of the Fenton reaction. Summary of the invention

[0009] In order to overcome the above-mentioned defects, the present invention provides a method for treating chemical washing wastewater of a water treatment filter membrane.

[0010] A method for treating chemical washing waste liquid of a water treatment filter membrane, wherein the chemical washing waste liquid includes acid washing waste liquid and alkaline washing waste liquid, comprising: S1, mixing the acid washing waste liquid and the alkaline washing waste liquid until the pH value of the obtained mixed liquid is 2-5, and then adding a catalyst and an oxidant to carry out a catalytic oxidation reaction; S2, after the catalytic oxidation reaction, injecting alkaline washing waste liquid into the mixed liquid to adjust the pH value so that the pH value of the mixed liquid is neutral or alkaline to carry out a flocculation reaction; and S3, after the flocculation reaction, adding a hardness remover to remove hardness, and an adsorbent to adsorb organic matter.

[0011] According to one embodiment of the present invention, the water treatment filtration membrane is one or a combination of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes.

[0012] According to another embodiment of the present invention, in step S1, the catalyst and the oxidant are added after the pH of the mixed solution is 3-4.

[0013] According to another embodiment of the present invention, the catalyst is selected from Fe 2+ , Fe 3+ 、Co 2+ 、Ni 2+ , Mn 2+ , Cu 2+ One or more of the following, preferably Fe 2+ ; The oxidant is selected from one or more of H2O2, ozone, and hypochlorite, preferably H2O2.

[0014] According to another embodiment of the present invention, the ratio of the added mass concentration of the oxidant to the COD concentration in the mixed solution is 0.1-10:1, preferably 0.5:1-2:1; the ratio of the mass concentration of the catalyst to the oxidant is 0.1-20:1, preferably 1:1-10:1.

[0015] According to another embodiment of the present invention, the catalytic oxidation reaction time is 0.5 to 4 hours, preferably 1 hour; the stirring intensity is 50 to 400 rpm, preferably 200 rpm.

[0016] According to another embodiment of the present invention, the pH of the mixed solution after adjustment with the alkali washing waste liquid in step S2 is 7 to 12, preferably 10 to 11.

[0017] According to another embodiment of the present invention, the flocculation reaction time in the step S2 is 1 to 10 minutes.

[0018] According to another embodiment of the present invention, the hardness remover includes one or more of sodium carbonate, sodium bicarbonate, cation exchange resin, and sodium hydroxide; preferably sodium carbonate and sodium hydroxide, sodium hydroxide is used to assist in adjusting the pH, preferably the pH is 10-11; the amount of sodium carbonate added is 0.5-4 times the concentration of the total hardness substance, preferably 1-1.5 times.

[0019] According to another embodiment of the present invention, the adsorbent and the de-hardening agent are added simultaneously, and the adsorbent includes one or more of powdered / granular activated carbon, zeolite, diatomaceous earth, and montmorillonite; preferably powdered activated carbon, the added concentration is 0.2 to 10 times, preferably 0.5 to 2 times, of the residual COD concentration in the mixed liquid after the catalytic oxidation reaction; the reaction time for de-hardening / adsorption is 0.2 to 2 hours, preferably 0.5 to 1 hour, and the stirring intensity is 200 rpm.

[0020] According to another embodiment of the present invention, the step S3 further includes: S4, adding a coagulant to carry out co-precipitation after the hardness removal and adsorption.

[0021] According to another embodiment of the present invention, a coagulant is added after hardness removal and adsorption, and the coagulant includes one or more of ferric sulfate, aluminum sulfate, ferric chloride, aluminum chloride, polyferric sulfate, and polyaluminum sulfate; preferably polyaluminum chloride (PAC), the addition amount is 20-200 mg / L, the coagulation reaction is 2-10 minutes, and the stirring intensity is 100-400 rpm; then polyacrylamide (PAM) is added, and the stirring intensity is reduced to 20-100 rpm, the addition amount of polyacrylamide is 1-20 mg / L, preferably 2-5 mg / L, the stirring time is continued for 2-5 minutes, and the coagulation reaction is allowed to stand for 0.5-4 hours.

[0022] According to another embodiment of the present invention, the treatment method is completed by a treatment device, which includes a reactor. The reactor is cylindrical on the top and conical on the bottom, and is provided with a water inlet, a dosing port, a water outlet, and a mud discharge port. The steps S1, S2 and S3 or the steps S1, S2, S3 and S4 are completed sequentially in the treatment device.

[0023] According to another embodiment of the present invention, the treatment device is also equipped with a pickling waste liquid storage tank, an alkaline washing waste liquid storage tank, an oxidant dosing device, a catalyst dosing device, a de-hardening agent dosing device, an adsorbent dosing device, a coagulant dosing device, an agitator, a pH sensor probe, a water pump, a valve switch, an automatic control system and connecting pipes.

[0024] The present invention ingeniously mixes the acid washing waste liquid and the alkaline washing waste liquid in different proportions at different reaction stages to create the catalytic reaction conditions required by (quasi) Fenton, avoiding the process disadvantages of neutralization first and then adding acid and alkali for adjustment, which not only meets the required conditions of (quasi) Fenton oxidation, but also avoids the problem of large acid and alkali consumption in the (quasi) Fenton oxidation process, and converts the complex hardness into free hardness, coupling chemistry and activated carbon adsorption; proposes a catalytic oxidation-hardness removal / adsorption coupling treatment process method for small batches of chemical washing waste liquid and highly polluted wastewater, and designs a sequencing batch chemical washing waste liquid integrated treatment device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic flow chart of a processing method according to one embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram of a processing device according to one embodiment of the present invention.

[0027] The reference numerals are described as follows:

[0028] 1: Pickling waste liquid storage tank

[0029] 2: Reactor

[0030] 3: Alkali washing waste liquid storage tank

[0031] 5: Sodium hydroxide solution tank

[0032] 6: Catalyst storage tank

[0033] 8: Oxidant storage tank

[0034] 10: Blender

[0035] 11: Hardness remover tank

[0036] 12: Activated carbon dosing tank

[0037] 13: Automatic control system

[0038] 14, 15: Coagulant storage tank

[0039] J1, J2: water inlet

[0040] J3, J4, J4, J5, J6: Dosing port

[0041] G1, G2, G3, G4, G5, G6: Pipeline

[0042] P1: Drainage outlet

[0043] P2: Mud discharge port DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with specific implementation modes.

[0045] The present invention proposes a method for treating chemical cleaning liquid for filtration membranes, particularly for membrane application scenarios involving acidic waste liquid and alkaline waste liquid, and can also be applied to other application scenarios involving simultaneous treatment of acidic wastewater and alkaline wastewater.

[0046] During the shutdown cleaning process of the water treatment filter membrane, it is mainly divided into the acid washing process and the alkaline washing process according to the cleaning object and the cleaning purpose. The acid washing process mainly adds hydrochloric acid, sulfuric acid, citric acid, etc. to remove the calcium and magnesium scaling problem on the membrane surface. Complexing agents such as EDTA are often added to complex the eluted calcium and magnesium to enhance the membrane washing effect. The alkaline washing process generally uses sodium hydroxide and oxidants such as sodium hypochlorite for cleaning. The main purpose is to clean organic pollutants on the membrane surface and kill the growing microorganisms. The cleaning objects can include microfiltration, ultrafiltration, nanofiltration, reverse osmosis membranes, etc. and their combinations. At present, the commonly used dual membrane system is the ultrafiltration-reverse osmosis filtration system. The above-mentioned acid washing and alkaline washing processes are typical cleaning methods commonly used in the industry. During the cleaning process, acid washing waste liquid and alkaline washing waste liquid are generated according to different pH values.

[0047] The pH of acid-washing wastewater is generally 1-2, which is strongly acidic and often contains eluents such as citric acid and EDTA, as well as high-concentration hardness under elution and in a complex state. The complexed calcium cannot be removed by conventional chemical precipitation methods. The pH of alkaline-washing wastewater is>11, which is strongly alkaline and often contains oxidants such as sodium hypochlorite. Both wastewaters contain high concentrations of organic pollutants, high salt content, residual eluents, etc.

[0048] The method of the present invention treats two waste liquids simultaneously. Figure 1 A schematic flow chart of a processing method according to an embodiment of the present invention is shown. Figure 1 As shown, the treatment method of the present invention includes: S1, after the acid washing waste liquid and the alkaline washing waste liquid are mixed until the pH value of the obtained mixed liquid is 2-5, a catalyst and an oxidant are added to carry out a catalytic oxidation reaction; S2, after the catalytic oxidation reaction, the alkaline washing waste liquid is injected into the mixed liquid to adjust the pH value so that the pH value of the mixed liquid is neutral or alkaline to carry out a flocculation reaction; and S3, after the flocculation reaction, a hardness remover is added to remove hardness, and an adsorbent is added to adsorb organic matter.

[0049] The above method may further include S4 after S3, wherein a coagulant is added to carry out co-precipitation after hardness removal and adsorption.

[0050] The processing method of the present invention can be Figure 2 The process is carried out in the illustrated apparatus. Figure 2 The processing device shown is only an example, and those skilled in the art may use other methods to implement the method of the present invention. Figure 2 Taking the treatment device as an example, the implementation mode of the present invention is explained. The treatment device is a batch type integrated reaction device, including a reactor 2, the upper part of the reactor 2 is cylindrical and the bottom is conical. Different water inlets J1, J2; dosing ports J3, J4, J5, J6; water outlet P1, mud outlet P2, etc. are provided. The reaction process in one reaction cycle includes water intake process and catalytic oxidation reaction process (S1), hardness removal process (S2), flocculation sedimentation process (S3), static drainage process (S4), and then re-intake of water for the next reaction cycle.

[0051] The treatment device is also equipped with a pickling waste liquid storage tank 1, an alkaline washing waste liquid storage tank 3, a sodium hydroxide solution tank 5, a catalyst storage tank 6, an oxidant storage tank 8, a stirrer 10, a hardness remover storage tank 11, an activated carbon dosing tank 12, a coagulant storage tank 14, and a coagulant aid storage tank 15. It is also equipped with a stirrer 10, a pH sensor probe (not shown in the figure), a water pump (not shown in the figure), a valve switch, an automatic control system 13, and connecting pipes G1, G2, G3, G4, G5, etc.

[0052] like Figure 2As shown, the pickling waste liquid storage tank 1 is connected to the water inlet J1 of the reactor 2 through the pipeline G1, and the alkali washing waste liquid storage tank 3 is connected to the water inlet J2 of the reactor 2 through the pipeline G2. In step S1, after all the pickling waste liquid flows into the reactor, the pH sensing probe is linked to control the inflow of part of the alkali washing waste liquid. When the pH rises to 2 to 5, the alkali washing waste liquid is stopped, and then the automatic control device is started to transport the catalyst and the oxidant through the pipelines G3 and G4 respectively, and the dosing ports J3 and J4 are added to the reactor 2 cavity, and the agitator 10 is started to react at 200rpm for 0.5 to 4h. In this step, the pH value of the mixed solution is adjusted by mixing part of the alkali washing waste liquid with the pickling liquid to meet the conditions of the (quasi) Fenton reaction, avoiding the large consumption of acid caused by first neutralizing all and then adjusting the acidic environment. In this step, a (quasi) Fenton reaction is carried out to deeply treat the organic matter in the waste liquid, and at the same time, the complexed hardness is converted into the free hardness, so that it can be removed by the hardness removal agent in the next step.

[0053] In step S2, after the catalytic oxidation is completed, the pH probe is fed back to the control system to flow into the remaining alkali washing waste liquid. The preferred pH for the hardness removal process is 10-11. If the total alkali liquid does not reach this pH, the sodium hydroxide reserve tank 5 switch can be started to flow in sodium hydroxide to increase the pH for flocculation reaction. The metal ions of the catalyst can be removed through this step.

[0054] In step S3, the hardness remover tank 11 connected to G5 is added through the drug inlet J5, and the activated carbon dosing tank 12 is also connected to the G5 pipeline, and the reaction is carried out for 0.5 to 1 hour under stirring conditions. In this step, free hardness can be removed, and organic matter can be adsorbed into an adsorbent such as activated carbon, further reducing organic pollutants in water.

[0055] In an optional embodiment, after step S3, the following is further included: S4, adding a coagulant for co-precipitation after hardness removal and adsorption. The coagulants PAC and PAM are stored in different dosing tanks 14 and 15, but are connected by two pipes and finally connected to the same dosing port J6 through pipe G6. After the coagulation reaction is completed, it is allowed to stand for 1 hour, the mud and water are separated, and the produced water flows out from the drain port P1, and the co-precipitates such as iron mud and calcium carbonate flow out from the bottom mud outlet P2.

[0056] In an optional embodiment, in step S1, the catalyst and the oxidant are added after the pH of the mixed solution is 3-4.

[0057] In an alternative embodiment, the catalyst is selected from Fe 2+ , Fe 3+ 、Co 2+ 、Ni 2+ , Mn 2+ , Cu 2+ One or more of the following. Preferably Fe 2+, such as FeSO4·7H2O, FeCl2. The oxidant is selected from one or more of H2O2, ozone, hypochlorite, preferably H2O2.

[0058] In an optional embodiment, the ratio of the added mass concentration of the oxidant to the COD concentration in the mixed solution is 0.1 to 10:1, preferably 0.5:1 to 2:1. The mass concentration ratio of the catalyst to the oxidant is 0.1 to 20:1, preferably 1:1 to 10:1.

[0059] In an optional embodiment, the catalytic oxidation reaction time is 0.5 to 4 hours, preferably 1 hour; the stirring intensity is 50 to 400 rpm, preferably 200 rpm.

[0060] In an optional embodiment, the pH of the mixed solution after adjustment with the alkaline washing waste liquid in step S2 is 7 to 12, preferably 10 to 11.

[0061] In an optional embodiment, the flocculation reaction time in step S2 is 1 to 10 minutes.

[0062] In an optional embodiment, the hardness remover includes one or more of sodium carbonate, sodium bicarbonate, cation exchange resin, and sodium hydroxide; sodium carbonate and sodium hydroxide are preferred, and sodium hydroxide is used to assist in adjusting the pH, preferably the pH is 10-11; the amount of sodium carbonate added is 0.5-4 times the concentration of the total hardness substance, preferably 1-1.5 times.

[0063] In an optional embodiment, the adsorbent and the de-hardening agent are added simultaneously, and the adsorbent includes one or more of powdered / granular activated carbon, zeolite, diatomaceous earth, and montmorillonite. Powdered activated carbon is preferred, and the added concentration is 0.2 to 10 times, preferably 0.5 to 2 times, of the residual COD concentration in the mixed solution after the catalytic oxidation reaction. The reaction time for de-hardening / adsorption is 0.2 to 2 hours, preferably 0.5 to 1 hour, and the stirring intensity is 200 rpm.

[0064] In an optional embodiment, a coagulant is added after hardness removal and adsorption, and the coagulant includes one or more of ferric sulfate, aluminum sulfate, ferric chloride, aluminum chloride, polyferric sulfate, and polyaluminum sulfate; preferably polyaluminum chloride, the addition amount is 20-200 mg / L, the coagulation reaction is 2-10 minutes, and the stirring intensity is 100-400 rpm; then polyacrylamide (PAM) is added, and the stirring intensity is reduced to 20-100 rpm, the addition amount of polyacrylamide is 1-20 mg / L, preferably 2-5 mg / L, the stirring time is continued for 2-5 minutes, and the flocculation reaction is allowed to stand for 0.5-4 hours.

[0065] The present invention is further described below by specific examples. However, these examples are merely exemplary and do not constitute any limitation to the protection scope of the present invention.

[0066] In the following examples and comparative examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0067] The following examples and comparative examples use the same acid wash waste liquid and alkali wash waste liquid, as shown in detail below.

[0068] According to the different membrane functions and cleaning methods, the membrane cleaning waste liquid produced is divided into the following four categories. The water quality analysis is shown in Table 1. According to the experimental principles and requirements, ultrafiltration alkaline washing and reverse osmosis alkaline washing are mixed as alkaline washing waste liquid, and ultrafiltration acid washing (lower cleaning frequency) and reverse osmosis acid washing are mixed as acid washing waste liquid. The water quality after mixing is shown in Table 2.

[0069] Table 1 Water quality of four chemical membrane washing wastewaters

[0070]

[0071] Table 2 Water quality of the mixed liquid of pickling waste liquid and alkali washing waste liquid

[0072]

[0073]

[0074] Note: According to the approximate proportion of wastewater generated by the on-site cleaning frequency, the volume ratio of ultrafiltration alkaline washing waste liquid to reverse osmosis alkaline washing waste liquid is approximately 1:1, and the volume ratio of reverse osmosis acid washing waste liquid to ultrafiltration acid washing waste liquid is 3:1; the total volume ratio of alkaline washing mixed liquid (including reverse osmosis alkaline washing and ultrafiltration alkaline washing) to acid washing mixed liquid (reverse osmosis acid washing and ultrafiltration acid washing) is approximately 1.2:1.

[0075] Example 1

[0076] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid, gradually add part of the alkaline wash waste liquid to the acid wash waste liquid to mix so that pH = 3, add 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate, stir and react for 1h, then add the remaining alkaline wash waste liquid, at this time the pH value is 7.85, add sodium hydroxide to adjust the pH to 11, add 500mg / L of sodium carbonate and 200mg / L of activated carbon to react for 30min, add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure COD 233mg / L, total hardness 67.0mg / L.

[0077] Example 2

[0078] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid, gradually add part of the alkaline wash waste liquid to the acid wash waste liquid to mix so that the pH = 4, add 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate, stir and react for 1h, then add the remaining alkaline wash waste liquid, at this time the pH value is 8.30, add sodium hydroxide to adjust the pH to 11, add 500mg / L of sodium carbonate and 200mg / L of activated carbon to react for 30min, add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure the COD 260mg / L, the total hardness 73.0mg / L.

[0079] Comparative Example 1

[0080] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid, gradually add part of the alkaline wash waste liquid to the acid wash waste liquid to mix so that the pH = 3, add 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate, stir and react for 1h, then add the remaining alkaline wash waste liquid and add sodium hydroxide to make the pH value 11, add 200mg / L of activated carbon and react for 30min, add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure the COD 271.0mg / L, and the total hardness 360.0mg / L.

[0081] Comparative Example 2

[0082] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid, gradually add part of the alkaline wash waste liquid to the acid wash waste liquid to mix so that the pH = 3, add 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate, stir and react for 1h, then add the remaining alkaline wash waste liquid, at this time the pH value is 7.85, add sodium hydroxide to adjust the pH to 11, add 500mg / L of sodium carbonate and react for 30min, add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure the COD 415mg / L, the total hardness 83.0mg / L.

[0083] Comparative Example 3

[0084] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid and mix them completely first. At this time, the pH is 8.05. Add 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate. At this time, the pH of the reaction system is 6.70. After stirring for 1h, add sodium hydroxide to adjust the pH to 11. Add 500mg / L of sodium carbonate and 200mg / L of activated carbon and react for 30min. Add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure COD 1015mg / L, total hardness 374mg / L.

[0085] Comparative Example 4

[0086] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid and mix them completely. At this time, the pH is 8.05. Sulfuric acid is added to adjust the pH to 3. 2000mg / L of hydrogen peroxide and 8000mg / L of ferrous sulfate are added. Stir and react for 1h. Then add sodium hydroxide solution to adjust the pH to 11. 500mg / L of sodium carbonate and 200mg / L of activated carbon are added to react for 30min. 50mg / L of PAC is added under slow stirring. After reacting at 200rpm for 5min, 3mg / L of PAM is added. After reacting at 50rpm for 5min, stand for 1h and take the supernatant to measure COD 290mg / L and total hardness 82.0mg / L.

[0087] Comparative Example 5

[0088] Take 0.3L of acid wash waste liquid and 0.36L of alkaline wash waste liquid and mix them completely. At this time, the pH is 8.05. Then add sodium hydroxide to adjust the pH to 11. Add 1000mg / L of sodium carbonate and 500mg / L of activated carbon to react for 30min. Add 50mg / L of PAC under slow stirring conditions, react at 200rpm for 5min, then add 3mg / L of PAM, react at 50rpm for 5min, let stand for 1h, take the supernatant and measure COD1250.0mg / L, total hardness 383.0mg / L.

[0089] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for treating chemical washing waste liquid of a water treatment filter membrane, wherein the chemical washing waste liquid comprises acid washing waste liquid and alkali washing waste liquid, characterized in that: include: S1, after the acid wash waste liquid and the alkali wash waste liquid are mixed until the pH value of the obtained mixed liquid is 2 to 5, a catalyst and an oxidant are added to perform a catalytic oxidation reaction; S2, after the catalytic oxidation reaction, injecting alkaline washing waste liquid into the mixed solution to adjust the pH value of the mixed solution to neutral or alkaline to perform flocculation reaction; as well as S3, after the flocculation reaction, a hardness remover is added to remove hardness, and an adsorbent is added to adsorb organic matter.

2. The processing method according to claim 1, characterized in that: The water treatment filtration membrane is one or a combination of microfiltration, ultrafiltration, nanofiltration and reverse osmosis membranes.

3. The processing method according to claim 1, characterized in that: In the step S1, the catalyst and the oxidant are added after the pH of the mixed solution is 3-4.

4. The processing method according to claim 1, characterized in that: The catalyst is selected from Fe 2+ , Fe 3+ 、Co 2+ 、Ni 2+ , Mn 2+ , Cu 2+ One or more of the following, preferably Fe 2+ ; The oxidant is selected from one or more of H2O2, ozone, and hypochlorite, preferably H2O2.

5. The processing method according to claim 1, characterized in that: The ratio of the added mass concentration of the oxidant to the COD concentration in the mixed solution is 0.1-10:1, preferably 0.5:1-2:1; the ratio of the mass concentration of the catalyst to the oxidant is 0.1-20:1, preferably 1:1-10:

1.

6. The processing method according to claim 5, characterized in that: The catalytic oxidation reaction time is 0.5 to 4 hours, preferably 1 hour; the stirring intensity is 50 to 400 rpm, preferably 200 rpm.

7. The processing method according to claim 1, characterized in that: In the step S2, the pH of the mixed solution after adjustment with the alkali washing waste liquid is 7 to 12, preferably 10 to 11.

8. The processing method according to claim 7, characterized in that: The flocculation reaction time in the step S2 is 1 to 10 minutes.

9. The processing method according to claim 1, characterized in that: The hardness remover includes one or more of sodium carbonate, sodium bicarbonate, cation exchange resin, and sodium hydroxide; sodium carbonate and sodium hydroxide are preferred, and sodium hydroxide is used to assist in adjusting the pH, preferably the pH is 10-11; the amount of sodium carbonate added is 0.5-4 times the concentration of the total hardness substance, preferably 1-1.5 times.

10. The processing method according to claim 1, characterized in that: The adsorbent is added simultaneously with the de-hardening agent, and the adsorbent includes one or more of powdered / granular activated carbon, zeolite, diatomaceous earth, and montmorillonite; powdered activated carbon is preferred, and the added concentration is 0.2 to 10 times, preferably 0.5 to 2 times, of the residual COD concentration in the mixed liquid after the catalytic oxidation reaction; the reaction time for de-hardening / adsorption is 0.2 to 2 hours, preferably 0.5 to 1 hour, and the stirring intensity is 200 rpm.

11. The processing method according to claim 1, characterized in that: The S3 step further includes: S4, after the hardness removal and adsorption, a coagulant is added to carry out co-precipitation.

12. The processing method according to claim 11, characterized in that: After hardness removal and adsorption, a coagulant is added, the coagulant includes one or more of ferric sulfate, aluminum sulfate, ferric chloride, aluminum chloride, polyferric sulfate, and polyaluminum sulfate; preferably polyaluminum chloride, the addition amount is 20-200 mg / L, the coagulation reaction is 2-10 minutes, and the stirring intensity is 100-400 rpm; then polyacrylamide is added, and the stirring intensity is reduced to 20-100 rpm, the addition amount of polyacrylamide is 1-20 mg / L, preferably 2-5 mg / L, the stirring time is continued for 2-5 minutes, and the coagulation reaction is allowed to stand for 0.5-4 hours, preferably 1 hour.

13. The processing method according to any one of claims 1 to 12, characterized in that: The treatment method is completed by a treatment device, which includes a reactor. The reactor has a cylindrical upper portion and a conical bottom, and is provided with a water inlet, a dosing port, a water outlet, and a mud discharge port. The steps S1, S2 and S3 or the steps S1, S2, S3 and S4 are completed sequentially in the treatment device.

14. The processing method according to claim 13, characterized in that: The treatment device is also equipped with a pickling waste liquid storage tank, an alkali washing waste liquid storage tank, an oxidant dosing device, a catalyst dosing device, a de-hardening agent dosing device, an adsorbent dosing device, a coagulant dosing device, an agitator, a pH sensor probe, a water pump, a valve switch, an automatic control system and connecting pipes.

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