CN112225392A - Treatment method and treatment system for electroplating cleaning wastewater - Google Patents

Treatment method and treatment system for electroplating cleaning wastewater Download PDF

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Publication number
CN112225392A
CN112225392A CN202010951691.9A CN202010951691A CN112225392A CN 112225392 A CN112225392 A CN 112225392A CN 202010951691 A CN202010951691 A CN 202010951691A CN 112225392 A CN112225392 A CN 112225392A
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treatment
tank
wastewater
anaerobic
activated sludge
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叶伟炳
李琴
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Guangdong Wenyang Environmental Technology Co ltd
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Guangdong Wenyang Environmental Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water, or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/048—Purification of waste water by evaporation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/30—Aerobic and anaerobic processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Abstract

The invention relates to a method and a system for treating electroplating cleaning wastewater. The treatment method of the electroplating cleaning wastewater comprises the following steps: adjusting the pH value of electroplating cleaning wastewater to be treated to 8-10, adding a precipitator and a flocculating agent, stirring, settling and filtering to obtain a first treatment solution; treating the first treatment solution by an anaerobic-aerobic activated sludge process to remove part of reducing substances and ammonia nitrogen to obtain a second treatment solution; adjusting the pH value of the second treatment liquid to 5-6, and then removing inorganic salts and organic matters through reverse osmosis membrane treatment to obtain produced water and concentrated water; and carrying out evaporation, crystallization and desalination treatment on the concentrated water. The treatment method has high purification efficiency.

Description

Treatment method and treatment system for electroplating cleaning wastewater
Technical Field
The invention relates to the technical field of electroplating wastewater treatment, in particular to a treatment method and a treatment system for electroplating cleaning wastewater.
Background
Electroplating cleaning wastewater (electroplating cleaning-water) is wastewater discharged in the cleaning process of a cleaning tank of a plating part, and is one of electroplating wastewater. The heavy metal content of the part of wastewater is not very high, but the wastewater can be discharged after reaching the standard after treatment, otherwise, water eutrophication, black and odorous pollution and the like can be caused, and the environment is seriously influenced.
The traditional electroplating cleaning wastewater treatment mode is to uniformly treat other wastewater generated by electroplating after mixing with the wastewater, such as waste liquid of overflowing, running, dripping, leaking and the like caused by electroplating pretreatment wastewater, waste plating solution, process equipment and other reasons. At present, chemical precipitation, electrolysis, adsorption, ion exchange, oxidative decomposition, microbial decomposition, electrochemical methods and the like are mainly used for treating electroplating wastewater in industry, wherein secondary pollution, environmental damage and the like are easily caused by slight improper treatment. In addition, the traditional electroplating wastewater treatment method is complex, difficult to operate, high in cost and low in purification efficiency.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
Therefore, a treatment method and a treatment system for electroplating cleaning wastewater are needed to be provided, and the problem that the existing electroplating cleaning wastewater treatment and purification efficiency is low is solved.
The technical scheme of the invention is as follows:
a method for treating electroplating cleaning wastewater comprises the following steps:
adjusting the pH value of electroplating cleaning wastewater to be treated to 8-10, adding a precipitator and a flocculating agent, stirring, settling and filtering to obtain a first treatment solution;
treating the first treatment solution by an anaerobic-aerobic activated sludge process to remove part of reducing substances and ammonia nitrogen to obtain a second treatment solution;
adjusting the pH value of the second treatment liquid to 5-6, and then removing inorganic salts and organic matters through reverse osmosis membrane treatment to obtain produced water and concentrated water;
and carrying out evaporation, crystallization and desalination treatment on the concentrated water.
In some of these embodiments, the precipitating agent comprises calcium chloride (CaCl)2) The flocculant comprises polyaluminum chloride (PAC) and Polyacrylamide (PAM).
In some of these embodiments, the weight ratio of the polyaluminum chloride to the polyacrylamide is (9-10.5): 1.
In some of these embodiments, the anaerobic-aerobic activated sludge process treatment comprises an anaerobic tank treatment and an aerobic tank treatment; controlling the pH value of the anaerobic tank to be 7-9, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 1-2 h; controlling the pH value of the aerobic pool to be 7-9, the dissolved oxygen to be 1.8-2.5 mg/L, the sludge age to be 20-35 d, the activated sludge concentration to be 2000-6000 mg/L, the average flow rate to be 0.3-0.5 m/s, and the external reflux amount to be 35-45%.
In some of these embodiments, the aerobic tank treatment employs oxidation ditch sewage treatment.
In some embodiments, the pH regulator used for regulating the pH value of the electroplating cleaning wastewater to be treated to 8-10 is sodium hydroxide.
In some embodiments, the pH adjusting agent used for adjusting the pH of the second treatment liquid to 5-6 is hydrochloric acid.
In some of the embodiments, a step of inclined tube sedimentation tank treatment is further included between the anaerobic-aerobic activated sludge process treatment and the reverse osmosis membrane treatment step.
In some embodiments, the evaporative crystallization desalination treatment is performed by using a vapor mechanical recompression evaporation device, the vapor mechanical recompression evaporation device comprises a plurality of heat exchange tubes, and the flow rate of liquid in each heat exchange tube is controlled to be 1.5 m/s-3.5 m/s.
Another object of the present invention is to provide a treatment system for electroplating cleaning wastewater, comprising:
the pretreatment device comprises a reaction tank and a primary sedimentation tank which are sequentially communicated, wherein a precipitator and a flocculating agent are added into the reaction tank and are used for carrying out a precipitation reaction and a flocculation reaction with the electroplating cleaning wastewater; the primary sedimentation tank is used for sedimentation of the wastewater after the precipitation reaction and the flocculation reaction;
the activated sludge device (A/O device) comprises an anaerobic tank and an aerobic tank which are communicated in a circulating way, the anaerobic tank is communicated with the primary sedimentation tank, and the activated sludge device is used for removing part of reducing substances and ammonia nitrogen in the wastewater treated by the pretreatment device;
a reverse osmosis membrane treatment device (RO device) for removing inorganic salts and organic substances in the wastewater treated by the activated sludge device; and
and the evaporative crystallization desalination treatment device (MVR device) is used for carrying out evaporative crystallization desalination treatment on the wastewater treated by the reverse osmosis membrane treatment device.
In some embodiments, the treatment system further comprises an inclined tube sedimentation tank arranged between the activated sludge treatment device and the reverse osmosis membrane treatment device, wherein the inclined tube sedimentation tank is used for receiving and settling the wastewater treated by the activated sludge treatment device, and transferring supernatant after settling treatment to the reverse osmosis membrane treatment device.
In some embodiments, the treatment system further comprises a sludge concentration tank, the sludge concentration tank is communicated with the primary sedimentation tank and/or the inclined tube sedimentation tank, and the sludge concentration tank is used for receiving sludge from the primary sedimentation tank and/or the inclined tube sedimentation tank and concentrating the sludge.
The principle and advantages of the invention are as follows:
1. according to the invention, aiming at the water quality characteristics of cleaning wastewater in an electroplating workshop, firstly, a precipitator and a flocculating agent are added to remove insoluble substances, colloids and phosphate ions in the wastewater, supernate and filtrate enter an A/O system to remove most of reducing substances and ammonia nitrogen in the wastewater, then inorganic salt and organic matters in the wastewater are removed through membrane treatment of an RO system to obtain produced water and concentrated water, the produced water is discharged or recycled after reaching the standard, and the concentrated water can be discharged after reaching the standard after being evaporated, crystallized and desalted through an MVR evaporation system, so that the pollution to the environment is reduced. And the method is innovated by combining with the reality on the basis of referring to the traditional process method, thereby improving the wastewater treatment efficiency and the social and economic benefits, saving energy and reducing emission.
2. The invention can discharge the electroplating cleaning wastewater after reaching the standard through the reaction tank, the primary sedimentation tank, the activated sludge (A/O) device, the inclined tube sedimentation tank, the reverse osmosis membrane treatment (RO) device and the evaporative crystallization desalination treatment (MVR) device in sequence, and has simple operation and high efficiency. Specifically, the pH value of electroplating cleaning wastewater to be treated is adjusted to 8-10, and a precipitator CaCl is added into a reaction tank2And flocculating agent (PAC + PAM), stirring to make precipitant and phosphate radical ion in waste waterReacting to generate sediment, adsorbing and combining the generated sediment, suspended particles, colloid and the like in the wastewater with a flocculating agent to form larger particles, allowing the wastewater to enter a primary sedimentation tank for sedimentation, allowing supernatant to enter an A/O system, allowing turbid liquid to enter a sludge concentration tank for concentration, filtering and dehydrating bottom mud for outward transportation, allowing filtrate and the settled supernatant to enter the A/O system for treatment, decomposing macromolecular organic matters in the wastewater into micromolecules such as methane and carbon dioxide by using anaerobic microorganisms in an anaerobic tank to remove part of ammonia nitrogen, allowing the micromolecule organic matters to enter an aerobic tank, removing most of reducing substances in the wastewater through aerobic aeration purification to reduce COD, allowing part of the wastewater to flow back to the anaerobic tank after aerobic reaction is finished, allowing part of the wastewater to enter an inclined tube sedimentation tank, allowing sludge in the inclined tube sedimentation tank to be concentrated again for dehydration and outward transportation, and adjusting the pH value of the supernatant to 5-6, and (4) entering an RO system, desalting by utilizing a semipermeable membrane selective permeability principle, and evaporating, concentrating, crystallizing and desalting by using an MRV system to reach the discharge standard.
3. Adopt the RO system to carry out membrane separation desalination, reduced the handling capacity to before waste water gets into the RO system, adjust pH value to 5 ~ 6, turn into the ammonium salt ion with the ammonia nitrogen that dissolves in the waste water, improved the effect of getting rid of ammonia nitrogen in the waste water greatly, improved the play water quality of system.
4. The MVR evaporation system is adopted to evaporate, concentrate, crystallize and desalt the wastewater, so that the scaling problem can be effectively solved, and the energy consumption of the operation of the wastewater treatment system is reduced.
5. The inclined tube sedimentation tank utilizes the laminar flow principle, improves the treatment capacity compared with the common sedimentation tank, shortens the sedimentation distance of particles, shortens the sedimentation time, increases the sedimentation area of the sedimentation tank and improves the treatment efficiency; and the floor area of the inclined tube sedimentation tank is small.
Drawings
FIG. 1 is a schematic view of an electroplating cleaning wastewater treatment system according to an embodiment of the present invention.
Detailed Description
In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
One embodiment of the invention provides a method for treating cleaning wastewater in an electroplating workshop, which comprises the following steps of S10-S40.
S10, adjusting the pH value of the electroplating cleaning wastewater to be treated to 8-10, adding a precipitator and a flocculating agent, stirring, settling and filtering to obtain a first treatment solution.
After the pH value of electroplating cleaning wastewater to be treated is adjusted to 8-10, a precipitator and a flocculating agent are added, stirring is carried out to enable the precipitator to react with phosphate ions in the wastewater to form precipitates, insoluble impurities, suspended colloids and the like in the wastewater react with the flocculating agent and are mutually adsorbed to form larger particles, the precipitates are easy to settle, and then the phosphate ions, the colloids and the insoluble impurities in the wastewater are removed through settling and filtering.
In some embodiments, the pH value of the electroplating cleaning wastewater to be treated is adjusted to 8-10, and the pH adjusting agent is sodium hydroxide.
In some embodiments, the precipitating agent is calcium chloride.
The reaction formula for removing phosphate ions by adding calcium chloride into electroplating cleaning wastewater is as follows: 3Ca2++2PO4 3-＝Ca3(PO4)2↓. Calcium chloride is used as a precipitator, can quickly form precipitate with phosphate ions, and can not bring new pollution sources.
In some embodiments, the flocculant comprises polyaluminum chloride and polyacrylamide.
In some embodiments, the weight ratio of polyaluminum chloride to polyacrylamide is (9-10.5): 1. Further, the weight ratio of polyaluminium chloride to polyacrylamide is 10: 1.
S20, removing part of reducing substances and ammonia nitrogen from the first treatment liquid by an anaerobic-aerobic activated sludge process to obtain a second treatment liquid.
Most of reducing substances and ammonia nitrogen in the electroplating cleaning wastewater can be well removed by adopting an A/O method.
In some embodiments, anaerobic-aerobic activated sludge process treatment includes anaerobic tank treatment and aerobic tank treatment; controlling the pH value of the anaerobic tank to be 7-9, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 1-2 h; controlling the pH value of the aerobic tank to be 7-9, the dissolved oxygen to be 1.8-2.5 mg/L, the sludge age to be 20-35 d, the activated sludge concentration to be 2000-6000 mg/L, the average flow rate to be 0.3-0.5 m/s, and the external reflux amount to be 35-45%.
It is understood that the external reflux amount refers to the amount of sewage flowing from the aerobic tank to the anaerobic tank.
Specifically, the inventor determines that the external reflux amount is 35% -45% according to the removal rate of COD of the electroplating cleaning wastewater, and a buffer section is arranged in the process of refluxing the wastewater to the anaerobic tank, so that the content of DO (dissolved oxygen) in water can be reduced, and the influence on the anaerobic section is avoided.
Further, the aerobic tank adopts an oxidation ditch for sewage treatment.
The sewage treatment in the oxidation ditch belongs to an activated sludge method of delayed aeration, an aeration tank of the method is in the shape of a long and narrow annular ditch which is connected end to end, continuous water inlet and outlet can be kept, and the microbial sludge generated in the oxidation ditch can stably survive and grow while the sewage is aerated and purified, so that the treatment steps can be simplified, and the treatment efficiency can be improved.
S30, adjusting the pH value of the second treatment liquid to 5-6, and then removing inorganic salts and organic matters through reverse osmosis membrane treatment to obtain produced water and concentrated water. Wherein the produced water can be directly discharged or recycled, and the concentrated water enters the next step for treatment.
Before the second treatment liquid is subjected to reverse osmosis membrane treatment, the pH value of the second treatment liquid is adjusted to 5-6, and ammonia molecules dissolved in the second treatment liquid can be converted into ammonium ions, so that ammonia nitrogen exists in the form of ammonium salt, and the removal efficiency of the ammonia nitrogen in the wastewater is greatly improved.
In some embodiments, the pH adjusting agent used for adjusting the pH value of the second treatment liquid to 5-6 is hydrochloric acid.
And S40, carrying out evaporation crystallization desalination treatment on the concentrated water.
In some embodiments, the evaporative crystallization desalination treatment is performed by using a vapor mechanical recompression evaporation device (MVR device) which comprises a plurality of heat exchange tubes, and the flow rate of liquid in each heat exchange tube is controlled to be 1.5 m/s-3.5 m/s.
The inventor finds through a large number of experiments that the RO concentrated water and the forced circulation liquid are mixed and then are distributed into the heat exchange tubes through the forced circulation pump, the liquid speed in each heat exchange tube is controlled to be 1.5-3.5 m/s, and the scaling probability can be well reduced so as to avoid influencing the heat exchange efficiency. When the circulating liquid flows from the heat exchange tube, the circulating liquid is heated by heat generated by condensation of steam outside the heat exchange tube, the pressure in the heat exchange tube is controlled to be lower than the saturated steam pressure at the temperature, and concentrated water cannot boil in the heat exchange tube, so that evaporation cannot be realized.
In some embodiments, the forced circulation pump of the MVR device is controlled by Variable Frequency (VFD), and the frequency is controlled to be 0-50 Hz. When the MVR device is initially started to operate, the RO concentrated water is low in Total Dissolved Solids (TDS) and small in specific gravity, the frequency of the forced circulation pump is automatically adjusted within the range of 0-50 Hz according to the specific gravity and the outlet pressure of the concentrated water, and the circulation flow demand can be met.
In some embodiments, the method for treating electroplating cleaning wastewater further comprises a step of inclined tube sedimentation tank treatment between the anaerobic-aerobic activated sludge process treatment and the reverse osmosis membrane treatment step.
Further, the process parameters of the inclined tube sedimentation tank treatment are as follows: 0.5T/H treatment capacity, and the size of the inclined tube sedimentation tank is as follows: length × width × height is 3m × 1.5m × 2.4 m.
Another embodiment of the present invention provides a system 100 for treating wastewater from electroplating cleaning, which comprises a pretreatment apparatus 110, an activated sludge apparatus (A/O apparatus) 120, a reverse osmosis membrane treatment apparatus (RO apparatus) 140, and an evaporative crystallization desalination treatment apparatus (MVR apparatus) 150, connected in series as shown in FIG. 1.
Wherein, the pretreatment device 110 is used for removing phosphorus and insoluble impurities from the electroplating cleaning wastewater to be treated; the pretreatment device 110 comprises a reaction tank 111 and a primary sedimentation tank 113 which are sequentially communicated, wherein a precipitator and a flocculating agent are added into the reaction tank 111 and are used for carrying out a precipitation reaction and a flocculation reaction with the electroplating cleaning wastewater. The A/O device 120 is used for removing part of COD and ammonia nitrogen in the wastewater treated by the pretreatment device; the A/O device 120 comprises an anaerobic tank 121 and an aerobic tank 123 which are circularly communicated, wherein the anaerobic tank 121 is communicated with the primary sedimentation tank 113.
The RO apparatus 140 serves to remove inorganic salts and organic matters in the wastewater treated by the a/O apparatus 120.
The RO apparatus 140 performs membrane separation and desalination using the principle of selective permeability of a semi-permeable membrane, and when a certain pressure is applied to wastewater on the surface of the semi-permeable membrane, water molecules in the wastewater can permeate the membrane to enter the water production side, and inorganic salts and macromolecular organic substances dissolved in the wastewater are trapped and removed. The method has the characteristics of good effluent quality, low operation energy consumption, simple operation and maintenance and equipment investment saving.
In some embodiments, the RO device 140 is provided with a cartridge filter (not shown). In order to improve the removing and intercepting effects of the semipermeable membrane on ammonium ions and the like, the wastewater is firstly conveyed to a cartridge filter by a water feeding pump before passing through the semipermeable membrane so as to ensure the quality of inlet water and avoid impact abrasion and damage to a high-pressure pump impeller and an osmotic membrane caused by particles possibly contained in the wastewater. The wastewater from the A/O device 120 passes through a cartridge filter and then enters a high-pressure pump to increase the pressure, and then enters a membrane separation system, the produced water after membrane separation can be directly discharged or recycled after reaching the detection, and the concentrated water enters the MVR device 150 to be evaporated, concentrated, crystallized and desalted.
The MVR unit 150 is used for evaporating, concentrating, crystallizing and desalting the wastewater treated by the RO unit 140.
In some embodiments, the treatment system further comprises a tube settler 130 disposed between the a/O unit 120 and the RO unit 140 for receiving and settling treated wastewater from the a/O unit 120 and transferring the settled supernatant to the RO unit 140.
In some embodiments, the number of the tube settler 130 may be 1 or more.
In some embodiments, the treatment system 100 further comprises a sludge concentration tank 160, and the sludge concentration tank 160 is in communication with the primary sedimentation tank 113 and/or the inclined tube sedimentation tank 130, respectively, and is configured to receive sludge from the primary sedimentation tank 113 and/or the inclined tube sedimentation tank 130 and concentrate the sludge.
In some embodiments, the treatment system 100 further comprises a filter press 170 for filter pressing sludge generated during the wastewater treatment process, wherein the filter-pressed dry sludge can be transported out of the solid.
In some embodiments, the a/O unit 120 further comprises an intermediate tank 125 for receiving wastewater from the aerobic tank 123 and returning a portion of the wastewater to the anaerobic tank 121 and sending a portion of the wastewater to the tube settler 130.
In some embodiments, the aerobic tank 123 is configured as an oxidation ditch.
The oxidation ditch is in the shape of a long and narrow annular ditch which is connected end to end, wherein the aeration device adopts a surface aerator. Therefore, the form of the oxidation ditch is adopted for delayed aeration, continuous water inlet and outlet circulation is kept, microorganisms in the oxidation ditch can stably survive and grow in sludge, and the microorganisms react in the aeration and purification of the sewage, so that the treatment steps are greatly simplified.
The treatment process of the electroplating cleaning wastewater according to the present invention will be further described with reference to FIG. 1.
Electroplating cleaning wastewater to be treated is collected and enters a reaction tank 111, phosphate ions react with a precipitator to generate precipitates, suspended matters, colloids, insoluble impurities and the like in the wastewater rapidly react with PAC and PAM through stirring of a stirrer in the reaction tank 111, and the suspended matters, the colloids, the insoluble impurities and the like are adsorbed to each other to be combined into larger particles, so that the wastewater is easy to settle. The wastewater treated by the reaction tank 111 enters the primary sedimentation tank 113 for sedimentation separation, turbid liquid enters the sludge concentration tank 160 for secondary concentration, mud and water separation is performed on the mud and water at the bottom of the primary sedimentation tank 113 through a mud and water separator, the sludge is dewatered by the filter press 170 and transported outward, filtrate and supernatant are filtered and then enter the anaerobic tank 121 of the A/O device 120, organic matters in the wastewater are decomposed into methane and carbon dioxide by using anaerobic microorganisms in the anaerobic tank 121, part of ammonia nitrogen is removed, the wastewater treated by the anaerobic tank 121 enters the aerobic tank 123, after the aerobic reaction is finished, the wastewater enters the intermediate tank 125, then a part of the wastewater continuously flows back to the anaerobic tank 121, a part of the wastewater enters the inclined tube sedimentation tank 130 for sedimentation, the settled sludge is concentrated again, the sludge is dewatered by the filter press 170 and transported outward, and the supernatant enters the RO device 140. The RO device 140 performs membrane separation on the supernatant through a membrane separation desalting process, removes inorganic salt and macromolecular organic matters (ammonia nitrogen) in the wastewater, obtains produced water and concentrated water, discharges or recycles the produced water after detection combination, and the concentrated water enters the MVR device 150 to be evaporated, concentrated, crystallized and desalted, and then solid impurities are transported outside, and distilled water is discharged or recycled after detection reaching the standard.
Specifically, the RO concentrated water is collected into a raw liquid tank of the MVR device 150, and is sent to a heat exchanger through a liquid conveying pump to exchange heat with distilled water; thus, the stock solution is preheated by high-temperature distilled water discharged from the system, a large amount of heat discharged by the distilled water is recovered, the preheated stock solution enters a crystallizer, the crystallizer adopts a salt leg crystallizer, and preheated incoming liquid wastewater enters an upper-layer flow bed of the salt leg crystallizer. The incoming liquid at a temperature slightly lower than the boiling point is in an unsaturated state, enters an upper laminar flow bed of the salt leg crystallizer tangentially, and contains a large amount of supersaturated circulating liquid of fine crystals, so that fine crystals can be eliminated, and the participation in circulation is reduced.
The heated circulating liquid flows out of the heater into the low-pressure separation chamber, high-temperature concentrated water is subjected to flash evaporation due to the sudden reduction of the pressure of the separation chamber, the concentrated water is concentrated, the concentrated water enters a centrifuge for separation after reaching the concentration multiple of the process requirement, solids are transported outside, and the centrifuged mother liquid returns to the stock solution tank.
The secondary steam produced by the separation chamber is provided with two layers of efficient demisting systems by setting a very sufficient liquid/steam separation area and separation height, wherein one layer adopts a folded plate type demister, and the other layer adopts a wire mesh type demister. And the device is provided with a PLC (programmable logic controller) for automatically controlling the arrangement of the product water cleaning and demisting net at regular intervals, so that the long-term treatment water quantity and the stable water quality of discharged water can be ensured.
And the secondary steam enters the gas washing system after passing through the efficient demisting system, the secondary steam after gas washing is pumped out by the compressor for temperature rise and pressure rise, and the steam after temperature rise is used as a steaming and heating source of the heater.
Distilled water condensed by the heater is stored in the distilled water tank and is conveyed by the distilled water pump to exchange heat with the incoming liquid wastewater and then is discharged out of the system.
Example 1 electroplating workshop cleaning wastewater treatment Process
The phosphorus content in the electroplating cleaning wastewater is 40 mg/L.
The electroplating cleaning wastewater is treated and then discharged by a reaction tank, a primary sedimentation tank, an anaerobic tank, an aerobic tank, an intermediate tank, an inclined tube sedimentation tank, an RO device and an MVR device in sequence, and the technological parameters of each specific stage are as follows:
a reaction tank: adding liquid alkali into the reaction tank, adjusting the pH value of the wastewater to 10, and adding CaCl2And flocculating agents PAC and PAM, and stirring for reaction.
An anaerobic tank: controlling the pH value to be 7.5, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 2 h.
An aerobic tank: controlling the pH value to be 8.5, the dissolved oxygen to be 1.9mg/L, the water conservancy retention time to be 30h, the sludge age to be 30d, the activated sludge concentration to be 4000mg/L, the average flow rate to be 0.3m/s and the external reflux amount to be 40 percent.
An inclined tube sedimentation tank: the treatment capacity was 0.5T/H, and the size of the inclined tube sedimentation tank was 3m × 1.5m × 2.4 m.
And (3) RO device: hydrochloric acid is added before the water enters the RO device to adjust the pH value of the inlet water to 5.5.
MVR device: the flow velocity of the heat exchange tube is controlled to be 2.5 m/s.
After the treatment is finished, the distilled water discharged from the system is detected, the total phosphorus content is 0.05mg/L, and other indexes such as COD, ammonia nitrogen and the like reach the discharge standard.
Example 2
48mg/L of phosphorus is contained in the electroplating cleaning wastewater.
The example 2 is the same as the example 1 in the treatment process flow, but the difference lies in the different process parameters of each stage, which are as follows:
a reaction tank: adding liquid alkali into the reaction tank, adjusting the pH value of the wastewater to 8, and adding CaCl2And flocculating agents PAC and PAM, and stirring for reaction.
An anaerobic tank: controlling the pH value to be 7, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 2 h.
An aerobic tank: controlling the pH value to be 7.5, the dissolved oxygen to be 2.2mg/L, the water conservancy retention time to be 40h, the sludge age to be 32d, the activated sludge concentration to be 3500mg/L, the average flow rate to be 0.35m/s and the external reflux amount to be 45 percent.
An inclined tube sedimentation tank:
and (3) RO device: hydrochloric acid is added before the water enters the RO device to adjust the pH value of the inlet water to be 6.
MVR device: the flow velocity of the heat exchange tube was controlled to 3.5 m/s.
After the treatment is finished, the distilled water discharged from the system is detected, the total phosphorus content is 0.06mg/L, and other indexes such as COD, ammonia nitrogen and the like reach the discharge standard.
Example 3
The electroplating cleaning wastewater contains 35mg/L of phosphorus.
The example 3 is the same as the treatment process flow of the example 1, and the difference is that the process parameters of each stage are different, specifically as follows:
a reaction tank: adding liquid alkali into the reaction tank, adjusting the pH value of the wastewater to 9, and adding CaCl2And flocculating agents PAC and PAM, and stirring for reaction.
An anaerobic tank: controlling the pH value to be 9, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 1.5 h.
An aerobic tank: controlling the pH value to be 7.5, the dissolved oxygen to be 2.2mg/L, the water conservancy retention time to be 20h, the sludge age to be 22d, the activated sludge concentration to be 3500mg/L, the average flow rate to be 0.35m/s and the external reflux amount to be 35 percent.
An inclined tube sedimentation tank:
and (3) RO device: hydrochloric acid is added before the water enters the RO device to adjust the pH value of the inlet water to be 6.
MVR device: the flow velocity of the heat exchange tube was controlled to 3.5 m/s.
After the treatment is finished, the distilled water discharged from the system is detected, the total phosphorus content is 0.05mg/L, and other indexes such as COD, ammonia nitrogen and the like reach the discharge standard.
Comparative example 1
The phosphorus content in the electroplating cleaning wastewater is 40 mg/L.
The processing process flow of the comparative example 1 is the same as that of the example 1, except that the process parameters of the reaction tank are different, and the specific steps are as follows:
a reaction tank: adding liquid alkali into the reaction tank, adjusting the pH value of the wastewater to 10, adding flocculating agents PAC and PAM, and stirring for reaction.
After the treatment is finished, the distilled water discharged from the system is detected, and the total phosphorus content is 5mg/L and does not reach the discharge standard.
Comparative example 2
The phosphorus content in the electroplating cleaning wastewater is 40 mg/L.
Comparative example 2 is the same as the treatment process flow of example 1, except that the process parameters of the reaction tank are different as follows:
a reaction tank: adding liquid alkali into the reaction tank, adjusting the pH value of the wastewater to 7.5, adding calcium chloride, flocculating agent PAC and PAM, and stirring for reaction.
After the treatment is finished, the distilled water discharged from the system is detected, the total phosphorus content is 3.5mg/L, and the discharge standard is not met.
Comparative example 3
The phosphorus content in the electroplating cleaning wastewater is 40 mg/L.
Comparative example 3 is the same as the treatment process of example 1, except that the process parameters of the RO plant are different as follows:
and (3) RO device: hydrochloric acid is added before the water enters the RO device to adjust the pH value of the inlet water to 6.5.
After the treatment is finished, the distilled water discharged from the system is detected, the total phosphorus content is 0.05mg/L, the ammonia nitrogen content is 30mg/L, and the discharge standard is not met.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The method for treating the electroplating cleaning wastewater is characterized by comprising the following steps of:
adjusting the pH value of electroplating cleaning wastewater to be treated to 8-10, adding a precipitator and a flocculating agent, stirring, settling and filtering to obtain a first treatment solution;
treating the first treatment solution by an anaerobic-aerobic activated sludge process to remove part of reducing substances and ammonia nitrogen to obtain a second treatment solution;
adjusting the pH value of the second treatment liquid to 5-6, and then removing inorganic salts and organic matters through reverse osmosis membrane treatment to obtain produced water and concentrated water;
and carrying out evaporation, crystallization and desalination treatment on the concentrated water.
2. The process of claim 1, wherein the precipitating agent comprises calcium chloride and the flocculating agent comprises polyaluminum chloride and polyacrylamide.
3. The treatment method according to claim 2, wherein the weight ratio of the polyaluminum chloride to the polyacrylamide is (9-10.5): 1.
4. The treatment method as set forth in claim 1, wherein the anaerobic-aerobic activated sludge process treatment includes an anaerobic tank treatment and an aerobic tank treatment; controlling the pH value of the anaerobic tank to be 7-9, the dissolved oxygen to be less than 0.2mg/L and the water conservancy residence time to be 1-2 h; controlling the pH value of the aerobic pool to be 7-9, the dissolved oxygen to be 1.8-2.5 mg/L, the sludge age to be 20-35 d, the activated sludge concentration to be 2000-6000 mg/L, the average flow rate to be 0.3-0.5 m/s, and the external reflux amount to be 35-45%.
5. The treatment method as claimed in claim 4, wherein the aerobic tank treatment adopts oxidation ditch sewage treatment.
6. The treatment method according to claim 1, wherein the pH adjusting agent used for adjusting the pH value of the electroplating cleaning wastewater to be treated to 8-10 is sodium hydroxide.
7. The treatment method according to claim 1, wherein the pH adjusting agent used for adjusting the pH of the second treatment liquid to 5 to 6 is hydrochloric acid.
8. The treatment method as set forth in claim 1, further comprising a step of inclined tube sedimentation treatment between the anaerobic-aerobic activated sludge process treatment and the reverse osmosis membrane treatment step.
9. The treatment method according to any one of claims 1 to 8, wherein the evaporative crystallization desalination treatment is carried out by using a vapor mechanical recompression evaporation device, the vapor mechanical recompression evaporation device comprises a plurality of heat exchange tubes, and the flow rate of liquid in each heat exchange tube is controlled to be 1.5m/s to 3.5 m/s.
10. A treatment system for electroplating cleaning wastewater is characterized by comprising the following components connected in sequence:
the pretreatment device comprises a reaction tank and a primary sedimentation tank which are sequentially communicated, wherein a precipitator and a flocculating agent are added into the reaction tank and are used for carrying out a precipitation reaction and a flocculation reaction with the electroplating cleaning wastewater; the primary sedimentation tank is used for sedimentation of the wastewater after the precipitation reaction and the flocculation reaction;
the activated sludge device comprises an anaerobic tank and an aerobic tank which are communicated in a circulating way, the anaerobic tank is communicated with the primary sedimentation tank, and the activated sludge device is used for removing part of reducing substances and ammonia nitrogen in the wastewater treated by the pretreatment device;
a reverse osmosis membrane treatment device for removing inorganic salts and organic matters in the wastewater treated by the activated sludge device; and
and the evaporative crystallization desalination treatment device is used for carrying out evaporative crystallization desalination treatment on the wastewater treated by the reverse osmosis membrane treatment device.
CN202010951691.9A 2020-09-11 2020-09-11 Treatment method and treatment system for electroplating cleaning wastewater Pending CN112225392A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104909490A (en) * 2015-05-19 2015-09-16 东风活塞轴瓦有限公司 Phosphating and chemical nickel-plating mixed comprehensive wastewater treatment process and automated device
CN205099501U (en) * 2014-07-24 2016-03-23 Oasys水有限公司 Water treatment system
CN107235601A (en) * 2017-06-14 2017-10-10 广东益诺欧环保股份有限公司 A kind of integrated electroplating treatment method for waste water, processing system and application

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN205099501U (en) * 2014-07-24 2016-03-23 Oasys水有限公司 Water treatment system
CN104909490A (en) * 2015-05-19 2015-09-16 东风活塞轴瓦有限公司 Phosphating and chemical nickel-plating mixed comprehensive wastewater treatment process and automated device
CN107235601A (en) * 2017-06-14 2017-10-10 广东益诺欧环保股份有限公司 A kind of integrated electroplating treatment method for waste water, processing system and application

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