A comprehensive zero-discharge treatment method for optoelectronic chip wastewater

Abstract

The present invention discloses a comprehensive treatment method for zero discharge of optoelectronic chip wastewater, which belongs to the field of arsenic-containing wastewater treatment. The method comprises the following steps: S1, fluorine removal and precipitation treatment of arsenic-containing and fluorine-containing wastewater, S2, flotation treatment of arsenic-containing wastewater, S3, pretreatment of arsenic-containing wastewater, S4, hydrolysis and biochemical treatment, S5, RO reverse osmosis membrane concentration treatment, S6, evaporation crystallization desalination, S7, arsenic-containing sludge treatment. By adopting the treatment process of the present application, zero discharge of optoelectronic chip wastewater can be achieved, and the wastewater treatment system can achieve "zero discharge" and meet the reuse standards. It can not only reduce the amount of external water and operating costs of the entire treatment system, but also increase the safety and stability of the wastewater treatment system, and has significant progressive significance. The process of the present application is reasonable, can effectively solve the problems of crystallization blockage and difficult precipitation of optoelectronic chip wastewater, ensure that the treated wastewater meets the enterprise reuse standards, has significant economic value and environmental value, and has practical significance for promoting the development of optoelectronic chips.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, in particular to the field of arsenic-containing wastewater treatment, and specifically to a zero-discharge comprehensive treatment method for optoelectronic chip wastewater. Background Art

[0002] The chemical formula of gallium arsenide is GaAs. It is a black-gray solid with a melting point of 1238°C. It can exist stably in air below 600°C and is not corroded by non-oxidizing acids. As an important semiconductor material, gallium arsenide has a lattice constant of 5.65×10 -10 m, with a bandgap of 1.4 electron volts. Gallium arsenide (GaAs) is internationally recognized as the most mature compound semiconductor material after silicon. It boasts superior properties such as high frequency, high electron mobility, high output power, low noise, and excellent linearity, making it one of the most important supporting materials for the optoelectronics and microelectronics industries. Second-generation semiconductors, represented by GaAs, are widely used in optoelectronics, microelectronics, and other fields, and have become a key technology for modern electronic information products and the information superhighway.

[0003] During the gallium arsenide production process, fluorides, large molecular organic matter and toxic and harmful arsenides will be produced. If not effectively treated, they will cause serious pollution to the environment.

[0004] Therefore, a new device and / or method is urgently needed to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of high-arsenic and high-salt wastewater treatment of optoelectronic chips.

[0006] The inventors discovered that optoelectronic chip wastewater primarily consists of wastewater from acid mist spray towers, polishing wastewater, dicing wastewater, and cooling tower wastewater. Effectively treating this wastewater has become a pressing issue.

[0007] The inventors divided optoelectronic chip wastewater into two parts: arsenic-containing and fluorine-containing wastewater and arsenic-containing wastewater; among them, arsenic-containing and fluorine-containing wastewater is the drainage of the acid mist spray tower in the gallium arsenide production process, and arsenic-containing wastewater includes polishing wastewater, dicing wastewater and cooling tower drainage.

[0008] In order to achieve the above object, the present invention provides a comprehensive zero-discharge treatment method for optoelectronic chip wastewater, comprising the following steps:

[0009] S1. Defluorination precipitation treatment of arsenic and fluorine-containing wastewater

[0010] Arsenic-containing and fluorine-containing wastewater is sent to a first wastewater regulating tank for temporary storage; a sequencing batch treatment method is adopted to send the arsenic-containing and fluorine-containing wastewater temporarily stored in the first wastewater regulating tank to the first wastewater sequencing batch tank, and alkali solution is added through a first alkali solution adding device to adjust the pH value of the wastewater in the first wastewater sequencing batch tank to 7.5-8.0, and then a defluoridating agent is added to the first wastewater sequencing batch tank through a first defluoridating agent adding device to reduce the fluoride ion concentration of the wastewater in the first wastewater sequencing batch tank to below 1 mg / L, and then flocculants PAC and PAM are added to the first wastewater sequencing batch tank in sequence through a first PAC and PAM adding device for coagulation and sedimentation, and a first sequencing batch supernatant and a first sequencing batch sludge are obtained, respectively;

[0011] S2. Flotation treatment of arsenic-containing wastewater

[0012] The arsenic-containing wastewater is sent to a second wastewater regulating tank for temporary storage; the arsenic-containing wastewater is sent to a second flotation device for flotation treatment. During the flotation process, alkali solution is added to the second flotation device through a second alkali solution adding device and the pH value of the wastewater in the second flotation device is adjusted to 10-11. PAC and PAM are then added to the second flotation device through a second PAC and PAM adding device. SS and oil substances in the wastewater are removed through flotation, and a second flotation liquid and a second flotation sludge are obtained respectively.

[0013] S3. Pretreatment of arsenic-containing wastewater

[0014] The second flotation device, the second arsenic and silicon removal reaction tank, the second coagulation and sedimentation tank, the second neutralization reaction tank, the first hydrolysis tank, and the first A / O biochemical tank are connected in sequence; iron salt is added to the second arsenic and silicon removal reaction tank through the second iron salt adding device, and then a destabilizing agent is added to the second arsenic and silicon removal reaction tank through the second destabilizing agent adding device, and finally sodium carbonate is added through the second sodium carbonate adding device to achieve arsenic and silicon removal and hardness removal treatment;

[0015] The second flotation liquid produced by the second flotation device is fed into the second arsenic and silicon removal reaction tank for treatment. The wastewater treated in the second arsenic and silicon removal reaction tank flows by gravity into the second coagulation and sedimentation tank. In the second coagulation and sedimentation tank, flocculants PAC and PAM are added through the fourth PAC and PAM addition device to perform coagulation and sedimentation, effectively adsorbing the co-precipitates of ferric arsenate and silicon formed in the wastewater. At the same time, SS in the wastewater is coagulated with the flocculants to form alum flocs, which are then separated from the water by natural sedimentation to obtain a second flocculated sludge and a second flocculated supernatant, respectively.

[0016] The second flocculated supernatant produced in the second coagulation sedimentation tank enters the second neutralization reaction tank; in the second neutralization reaction tank, acid is added through the second acid adding device to carry out a neutralization reaction;

[0017] S4. Hydrolysis and biochemical treatment

[0018] The supernatant of the first batch after treatment in the second arsenic and silicon removal reaction tank is fed into the first hydrolysis tank for hydrolysis, and the wastewater after treatment in the second neutralization reaction tank is fed into the first hydrolysis tank for hydrolysis; under the action of microorganisms in the first hydrolysis tank, large molecular lipid substances in the wastewater are degraded; the wastewater treated in the first hydrolysis tank is then fed into the first A / O biochemical tank, where the nitrification and denitrification actions of the microorganisms are utilized to degrade the pollutants in the wastewater, thereby obtaining a first biochemical liquid and a first biochemical sludge, respectively;

[0019] The first biochemical liquid produced in the first A / O biochemical pool flows into the first MBR membrane reactor by gravity for ultrafiltration treatment to obtain the first MBR filtrate;

[0020] S5, RO reverse osmosis membrane concentration treatment

[0021] The first MBR filtrate is sent to the first multi-stage RO membrane reactor for reverse osmosis treatment to intercept pollutants in the wastewater and obtain the first fresh water and membrane concentrated water; the first fresh water is sent to the first recycled water tank for temporary storage;

[0022] S6, evaporation crystallization desalination

[0023] The membrane concentrate produced by the first multi-stage RO membrane reactor is sent to the second MVR evaporation system for evaporation and crystallization treatment to obtain a second evaporation condensate and a second evaporation mother liquor respectively. The second evaporation condensate produced by the second MVR evaporation system is returned to the second arsenic and silicon removal reaction tank for further treatment;

[0024] S7. Treatment of arsenic-containing sludge

[0025] The first batch sludge produced by the first wastewater batch tank, the second flotation sludge produced by the second flotation device, the second flocculation sludge produced by the second coagulation sedimentation tank, and the first biochemical sludge produced by the first A / O biochemical tank can be respectively put into the third arsenic-containing sludge tank for temporary storage;

[0026] After the sludge in the third arsenic-containing sludge pool reaches a specified amount, the sludge is dehydrated using a third filter press dehydration device to obtain a third filter press filtrate and third filter press sludge respectively; the third filter press filtrate produced by the third filter press dehydration device is returned to the second wastewater regulating tank for further treatment.

[0027] The arsenic-containing and fluorine-containing wastewater is the wastewater from the acid mist spray tower in the gallium arsenide production process. The arsenic-containing wastewater includes one or more of polishing wastewater, slicing wastewater, and cooling tower wastewater.

[0028] The arsenic-containing and fluorine-containing wastewater comes from the waste gas generated in the dry etching process, which is sequentially subjected to dry adsorption, plasma water washing, and acid mist spraying to generate acidic wastewater and plasma water washing wastewater.

[0029] The main component of the arsenic- and fluorine-containing wastewater is hydrofluoric acid, and the arsenic- and fluorine-containing wastewater is discharged intermittently.

[0030] In step S3, the iron salt added by the second iron salt adding device is an iron salt coagulant.

[0031] Furthermore, in step S3, the iron salt added by the second iron salt adding device is ferrous sulfate.

[0032] In step S3, the ratio of the amount of the added iron ions to the amount of the arsenic ions in the sewage is ≥20.

[0033] The acid liquid added by the second acid liquid adding device is an inorganic acid.

[0034] The acid added by the second acid adding device is hydrochloric acid or sulfuric acid.

[0035] In step S4, the first biochemical liquid produced in the first A / O biochemical pool is then sent to the first MBR membrane reactor for ultrafiltration treatment to intercept SS in the wastewater and ensure that the effluent SDI is less than 3.

[0036] The first multi-stage RO membrane reactor is a two-stage RO membrane reactor or a three-stage RO membrane reactor.

[0037] In step S5, the first fresh water in the first recycled water tank is sent to the cooling tower for use as make-up water.

[0038] In step S6, the second evaporation product generated by the second MVR evaporation system is outsourced for processing.

[0039] In step S7, the third filter press sludge generated by the third filter press dewatering device is outsourced for treatment.

[0040] The optoelectronic chip wastewater zero-discharge comprehensive treatment device used in the above-mentioned method includes a first wastewater regulating tank for homogenizing and balancing arsenic-containing and fluorine-containing wastewater, a first wastewater sequencing batch tank, a first hydrolysis tank, a first A / O biochemical tank, a first MBR membrane reactor, a first multi-stage RO membrane reactor, a first recycled water tank, a second wastewater regulating tank for homogenizing and balancing arsenic-containing wastewater, a second flotation device, a second arsenic and silicon removal reaction tank, a second coagulation and sedimentation tank, a second neutralization reaction tank, a second MVR evaporation system, a third arsenic-containing sludge tank, a third filter press dehydration device, a first alkali solution adding device, a first defluoridant adding device, a first PAC and PAM adding device, a second alkali solution adding device, a second PAC and PAM adding device, a second iron salt adding device, a second destabilizer adding device, a second sodium carbonate adding device, a fourth PAC and PAM adding device, and a second acid adding device;

[0041] The first alkali solution adding device is connected to the first wastewater batch pool and the first alkali solution adding device can add alkali solution into the first wastewater batch pool, the first defluoridating agent adding device is connected to the first wastewater batch pool and the first defluoridating agent adding device can add defluoridating agent into the first wastewater batch pool, and the first PAC and PAM adding device is connected to the first wastewater batch pool and the first PAC and PAM adding device can add PAC and PAM into the first wastewater batch pool;

[0042] The first wastewater regulating tank is connected to the first wastewater sequencing batch tank, and the wastewater after homogenization and equalization treatment in the first wastewater regulating tank can enter the first wastewater sequencing batch tank to obtain the first sequencing batch supernatant and the first sequencing batch sludge respectively;

[0043] The first wastewater sequencing batch tank is connected to the first hydrolysis tank, and the first sequencing batch supernatant generated by the first wastewater sequencing batch tank can be fed into the first hydrolysis tank; the first hydrolysis tank is connected to the first A / O biochemical tank, and the wastewater treated by the first hydrolysis tank can enter the first A / O biochemical tank for biochemical treatment to obtain a first biochemical liquid and a first biochemical sludge, respectively; the first A / O biochemical tank is connected to the first MBR membrane reactor, and the first biochemical liquid treated by the first A / O biochemical tank can enter the first MBR membrane reactor for filtration to obtain a first MBR filtrate; the first MBR membrane reactor is connected to the first multi-stage RO membrane reactor, and the first MBR filtrate filtered by the first MBR membrane reactor can enter the first multi-stage RO membrane reactor for reverse osmosis treatment to obtain first fresh water and membrane concentrated water; the first multi-stage RO membrane reactor is connected to the first reuse water tank, and the first fresh water treated by the first multi-stage RO membrane reactor can be fed into the first reuse water tank for temporary storage;

[0044] The second alkali solution adding device is connected to the second flotation device and can add alkali solution into the second flotation device. The second PAC and PAM adding device is connected to the second flotation device and can add PAC and PAM into the second flotation device. The second wastewater regulating tank is connected to the second flotation device and the wastewater in the second wastewater regulating tank can enter the second flotation device for treatment to obtain second flotation liquid and second flotation sludge respectively.

[0045] The second flotation device is connected to the second arsenic and silicon removal reaction tank, and the second flotation liquid treated by the second flotation device can enter the second arsenic and silicon removal reaction tank for treatment. The second iron salt adding device is connected to the second arsenic and silicon removal reaction tank, and the second iron salt adding device can add iron salt to the second arsenic and silicon removal reaction tank. The second destabilizing agent adding device is connected to the second arsenic and silicon removal reaction tank, and the second destabilizing agent adding device can add destabilizing agent to the second arsenic and silicon removal reaction tank. The second sodium carbonate adding device is connected to the second arsenic and silicon removal reaction tank, and the second sodium carbonate adding device can add sodium carbonate to the second arsenic and silicon removal reaction tank.

[0046] The second arsenic and silicon removal reaction tank is connected to the second coagulation and sedimentation tank, and the wastewater treated in the second arsenic and silicon removal reaction tank can enter the second coagulation and sedimentation tank for treatment. The fourth PAC and PAM adding device is connected to the second coagulation and sedimentation tank, and the fourth PAC and PAM adding device can add PAC and PAM to the second coagulation and sedimentation tank to obtain a second flocculated sludge and a second flocculated supernatant, respectively.

[0047] The second coagulation sedimentation tank is connected to the second neutralization reaction tank, and the second flocculation supernatant after treatment in the second coagulation sedimentation tank can enter the second neutralization reaction tank. The second acid addition device is connected to the second neutralization reaction tank, and the second acid addition device can add acid to the second neutralization reaction tank to neutralize the second flocculation supernatant.

[0048] The second neutralization reaction tank is connected to the first hydrolysis tank and the wastewater treated in the second neutralization reaction tank can enter the first hydrolysis tank for hydrolysis;

[0049] The first multi-stage RO membrane reactor is connected to the second MVR evaporation system, and the membrane concentrated water produced by the first multi-stage RO membrane reactor can enter the second MVR evaporation system for evaporation treatment to obtain a second evaporation condensate and a second evaporation mother liquor respectively. The second MVR evaporation system is connected to the second arsenic and silicon removal reaction tank, and the second evaporation condensate produced by the second MVR evaporation system can be returned to the second arsenic and silicon removal reaction tank;

[0050] The first wastewater sequencing batch tank, the second air flotation device, the second coagulation sedimentation tank, and the first A / O biochemical tank are respectively connected to the third arsenic-containing sludge tank, and the first sequencing batch sludge produced by the first wastewater sequencing batch tank, the second air flotation sludge produced by the second air flotation device, the second flocculation sludge produced by the second coagulation sedimentation tank, and the first biochemical sludge produced by the first A / O biochemical tank can be respectively entered into the third arsenic-containing sludge tank for temporary storage;

[0051] The third arsenic-containing sludge pool is connected to the third filter press dewatering device, and the sludge in the third arsenic-containing sludge pool can enter the third filter press dewatering device for filter press treatment to obtain a third filter press filtrate and a third filter press sludge respectively. The third filter press dewatering device is connected to the second wastewater regulating tank, and the third filter press filtrate generated by the third filter press dewatering device can be returned to the second wastewater regulating tank for reuse.

[0052] The iron salt in the second iron salt adding device is ferrous sulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0054] Figure 1 This is the process flow chart of this application.

[0055] Figure 2 For example, the arsenic wastewater treatment equipment of a photoelectric chip project in Example 1 Figure 1 .

[0056] Figure 3 For example, the arsenic wastewater treatment equipment of a photoelectric chip project in Example 1 Figure 2 .

[0057] Markings in the figure: 1. The first wastewater regulating tank, 2. The first wastewater sequencing batch tank, 3. The second wastewater regulating tank, 4. The second flotation device, 5. The second arsenic and silicon removal reaction tank, 6. The second coagulation and sedimentation tank, 7. The second neutralization reaction tank, 8. The first hydrolysis tank, 9. The first A, O biochemical tank, 10. The first MBR membrane reactor, 11. The first multi-stage RO membrane reactor, 12. The first recycled water tank, 13. The second MVR evaporation system, 14. The third arsenic-containing sludge tank, 15. The third filter press dehydration device. DETAILED DESCRIPTION

[0058] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0059] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0060] The inlet and outlet concentrations of key water quality indicators of arsenic-containing wastewater from an optoelectronic chip project are shown in Table 1. In Table 1, the unit is mg / L, except for pH.

[0061] Table 1 Inlet and outlet water quality concentrations of key water quality indicators of arsenic-containing wastewater in a photoelectric chip project

[0062]

[0063] From the data in Table 1, we can find that the wastewater from this optoelectronic chip project has the following key areas of concern:

[0064] (1) Arsenic-containing wastewater is required to achieve zero discharge, so the operational stability of each system is crucial, and reducing the operating cost of the evaporation system is also very important;

[0065] (2) There is still a large amount of fluoride in the drainage of the acid mist spray tower. How to reduce the side effects of membrane system clogging and evaporation system clogging caused by fluoride removal while removing the fluoride is crucial for the stable operation of the system;

[0066] (3) In order to reduce water resource consumption, the main wastewater in the system comes from cooling tower drainage. Under normal circumstances, most of the cooling tower water comes from tap water. After natural concentration in the cooling tower, the concentration of calcium and magnesium ions in the wastewater is high (calcium and magnesium ions are at least 300 mg / L). In the MBR and RO membrane and MVR evaporation treatment process, high concentrations of calcium and magnesium ions will cause scaling and clogging problems, resulting in a significant reduction in treatment capacity, which will lead to frequent cleaning of the membrane system, which not only affects the service life of the membrane, but also because it is arsenic-containing wastewater, each cleaning is particularly troublesome and can easily lead to accidents. Therefore, it is also crucial to remove calcium and magnesium in the wastewater.

[0067] This embodiment provides a comprehensive zero-discharge treatment device for optoelectronic chip wastewater, comprising a first wastewater regulating tank, a first wastewater sequencing batch tank, a first hydrolysis tank, a first A / O biochemical tank, a first MBR membrane reactor, a first multi-stage RO membrane reactor, a first recycled water tank, a second wastewater regulating tank, a second flotation device, a second arsenic and silicon removal reaction tank, a second coagulation and sedimentation tank, a second neutralization reaction tank, a second MVR evaporation system, a third arsenic-containing sludge tank, a third filter press dewatering device, a first alkali solution addition device, a first defluoridant addition device, a first PAC and PAM addition device, a second alkali solution addition device, a second PAC and PAM addition device, a second iron salt addition device, a second destabilizer addition device, a second sodium carbonate addition device, a fourth PAC and PAM addition device, and a second acid solution addition device. The first wastewater regulating tank is primarily used to homogenize and equalize the amount of arsenic- and fluorine-containing wastewater, and the second wastewater regulating tank is primarily used to homogenize and equalize the amount of arsenic-containing wastewater.

[0068] In this structure, the first alkali solution adding device is connected to the first wastewater sequencing batch pool, and the first alkali solution adding device can add alkali solution into the first wastewater sequencing batch pool; the first defluoridating agent adding device is connected to the first wastewater sequencing batch pool, and the first defluoridating agent adding device can add defluoridating agent into the first wastewater sequencing batch pool; the first PAC and PAM adding device is connected to the first wastewater sequencing batch pool, and the first PAC and PAM adding device can add PAC and PAM into the first wastewater sequencing batch pool.

[0069] The first wastewater regulating tank is connected to the first wastewater sequencing batch tank. The wastewater treated by the first wastewater regulating tank for homogenization and equalization can be fed into the first wastewater sequencing batch tank to produce a first batch supernatant and a first batch sludge, respectively. The first wastewater sequencing batch tank is connected to the first hydrolysis tank. The first hydrolysis tank is connected to the first A / O biochemical tank. The wastewater treated in the first hydrolysis tank can be fed into the first A / O biochemical tank for biochemical treatment to produce a first biochemical liquid and a first biochemical sludge, respectively. The first A / O biochemical tank is connected to the first MBR membrane reactor. The first biochemical liquid treated in the first A / O biochemical tank can be fed into the first MBR membrane reactor for filtration to produce a first MBR filtrate. The first MBR membrane reactor is connected to the first multi-stage RO membrane reactor. The first MBR filtrate, filtered by the first MBR membrane reactor, can be fed into the first multi-stage RO membrane reactor for reverse osmosis treatment to produce first fresh water and membrane concentrate. The first multi-stage RO membrane reactor is connected to the first recycled water tank, and the first fresh water treated by the first multi-stage RO membrane reactor can be sent to the first recycled water tank for temporary storage. Further, in this embodiment, the first multi-stage RO membrane reactor is a two-stage RO membrane reactor or a three-stage RO membrane reactor.

[0070] The second alkali solution addition device is connected to the second flotation device and can add alkali solution to the second flotation device. The second PAC and PAM addition device is connected to the second flotation device and can add PAC and PAM to the second flotation device. The second iron salt addition device is connected to the second arsenic and silicon removal reaction tank and can add iron salt to the second arsenic and silicon removal reaction tank. The second destabilizer addition device is connected to the second arsenic and silicon removal reaction tank and can add destabilizer to the second arsenic and silicon removal reaction tank. The second sodium carbonate addition device is connected to the second arsenic and silicon removal reaction tank and can add sodium carbonate to the second arsenic and silicon removal reaction tank.

[0071] The second wastewater regulating tank is connected to the second flotation unit, where wastewater from the second wastewater regulating tank can be treated to produce a second flotation liquid and a second flotation sludge, respectively. The second flotation unit is connected to the second arsenic and silicon removal reaction tank, where the second flotation liquid treated by the second flotation unit can be treated to produce a second arsenic and silicon removal reaction tank. The second arsenic and silicon removal reaction tank is connected to the second coagulation and sedimentation tank, where wastewater treated by the second arsenic and silicon removal reaction tank can be treated to produce a second flocculated sludge and a second flocculated supernatant, respectively. The second coagulation and sedimentation tank is also connected to the second neutralization reaction tank, where the second flocculated supernatant treated by the second coagulation and sedimentation tank can be treated to produce a second flocculated sludge and a second flocculated supernatant, respectively. The second acid addition device is connected to the second neutralization reaction tank and can add acid to the second neutralization reaction tank to neutralize the second flocculation supernatant. The second neutralization reaction tank is connected to the first hydrolysis tank, and the wastewater treated in the second neutralization reaction tank can enter the first hydrolysis tank for hydrolysis.

[0072] In this embodiment, the first multi-stage RO membrane reactor is connected to a second MVR evaporation system. The membrane concentrate produced by the first multi-stage RO membrane reactor can enter the second MVR evaporation system for evaporation, producing a second evaporation condensate and a second evaporation mother liquor, respectively. The second MVR evaporation system is connected to a second arsenic and silicon removal reaction tank, and the second evaporation condensate produced by the second MVR evaporation system can be returned to the second arsenic and silicon removal reaction tank.

[0073] In this embodiment, the first wastewater batch tank, the second flotation unit, the second coagulation and sedimentation tank, and the first A / O biochemical tank are each connected to the third arsenic-containing sludge tank. The first batch sludge produced by the first wastewater batch tank, the second flotation sludge produced by the second flotation unit, the second flocculated sludge produced by the second coagulation and sedimentation tank, and the first biochemical sludge produced by the first A / O biochemical tank can each be temporarily stored in the third arsenic-containing sludge tank. The third arsenic-containing sludge tank is connected to the third filter press dewatering unit, and the sludge in the third arsenic-containing sludge tank can be filtered in the third filter press dewatering unit to obtain a third filter press filtrate and third filter press sludge, respectively. The third filter press dewatering unit is connected to the second wastewater regulating tank, and the third filter press filtrate produced by the third filter press dewatering unit can be returned to the second wastewater regulating tank for reuse. In this embodiment, the iron salt in the second iron salt addition device is ferrous sulfate.

[0074] This embodiment provides a comprehensive zero-discharge treatment method for optoelectronic chip wastewater, which includes the following steps.

[0075] S1. Defluorination precipitation treatment of arsenic and fluorine-containing wastewater

[0076] Arsenic-containing and fluorine-containing wastewater comes from the waste gas generated in the dry etching process, which undergoes dry adsorption, plasma water washing, and acid mist spraying to produce acidic wastewater and plasma water washing wastewater. The arsenic-containing and fluorine-containing wastewater is sent to the first wastewater regulating tank for temporary storage. The main component of the arsenic-containing and fluorine-containing wastewater is hydrofluoric acid, and it is discharged intermittently. To this end, this embodiment adopts a batch treatment method, and the arsenic-containing and fluorine-containing wastewater temporarily stored in the first wastewater regulating tank is sent to the first wastewater batch tank, and alkali is added through the first alkali solution adding device and the pH value of the wastewater in the first wastewater batch tank is adjusted to 7.5-8.0, and then the first defluorination agent adding device is used to add defluorination agent to the first wastewater batch tank and reduce the fluoride ion concentration of the wastewater in the first wastewater batch tank to below 1 mg / L, and then the flocculants PAC and PAM are added to the first wastewater batch tank in sequence through the first PAC and PAM adding devices for coagulation and precipitation, and the first batch supernatant and the first batch sludge are obtained respectively.

[0077] S2. Flotation treatment of arsenic-containing wastewater

[0078] The arsenic-containing wastewater is temporarily stored in the second wastewater regulating tank. The arsenic-containing wastewater is then fed into the second flotation unit for flotation treatment. During the flotation process, alkali is added to the second flotation unit via the second alkali addition device, and the pH of the wastewater in the second flotation unit is adjusted to 10-11. PAC and PAM are then added to the second flotation unit via the second PAC and PAM addition device. Flotation removes SS and oil from the wastewater, producing a second flotation liquid and a second flotation sludge, respectively.

[0079] S3. Pretreatment of arsenic-containing wastewater

[0080] The second flotation unit, the second arsenic and silicon removal reactor, the second coagulation and sedimentation tank, the second neutralization reactor, the first hydrolysis tank, and the first A / O biochemical tank are sequentially connected. Iron salts are added to the second arsenic and silicon removal reactor via the second iron salt addition unit; destabilizers are then added via the second destabilizer addition unit, and finally, sodium carbonate is added via the second sodium carbonate addition unit to achieve arsenic, silicon, and hardness removal. The second flotation liquid produced by the second flotation unit is fed to the second arsenic and silicon removal reactor for treatment. The treated wastewater is then fed to the second coagulation and sedimentation tank. In this second coagulation and sedimentation tank, flocculants PAC and PAM are added via the fourth PAC and PAM addition unit for coagulation and sedimentation, effectively adsorbing the coprecipitates of ferric arsenate and silicon formed in the wastewater. Simultaneously, SS in the wastewater reacts with the flocculants to form flocs, which are then separated by natural sedimentation to produce the second flocculated sludge and the second flocculated supernatant, respectively.

[0081] The second flocculated supernatant produced in the second coagulation sedimentation tank enters the second neutralization reaction tank, where acid is added through the second acid adding device to perform a neutralization reaction.

[0082] In this step, a certain amount of iron salt is added to the wastewater to react with the arsenate in the wastewater to form an arsenate precipitate to achieve the purpose of arsenic removal. In this step, the pH requirement for the water body is relatively high, generally within the range of 5.5-8.5; the present application adds ferrous sulfate, an iron salt coagulant, to adjust the acidity and base, and increase the iron content in the sewage, so that the iron ion content in the water is maintained at or above 1.5 mg / l. In this embodiment, the ratio of the added iron ions to the arsenic ions in the sewage shall not be less than 20:1, which can make the arsenic ion removal rate reach 80%-95%, thereby reducing the arsenic content in the wastewater to less than 0.5 mg / L.

[0083] Then, by adding a destabilizing agent, the stability of the sewage is destroyed, making it easier to precipitate, so as to reduce the problem of clogging of the back-end membrane system. At the same time, the present application adopts a double alkali method to remove calcium and magnesium ions in the wastewater. After being treated in the second arsenic and silicon removal reaction tank, the wastewater enters the second coagulation sedimentation tank, and flocculants PAC and PAM are added for a period of coagulation and sedimentation. Through the adsorption bridging effect of PAC and PAM, the co-precipitates of iron arsenate and silicon formed in the wastewater are effectively adsorbed. In the present application, SS in the wastewater is coagulated with a flocculant to form alum flowers, and then naturally precipitated in a sedimentation tank to achieve mud and water separation. After the wastewater is precipitated, the obtained second flocculation supernatant flows to the back-end biochemical system, and the obtained second flocculation sludge is pumped to the third arsenic-containing sludge tank.

[0084] S4. Hydrolysis and biochemical treatment

[0085] The supernatant from the first batch of treatment in the second arsenic and silicon removal reaction tank is fed into the first hydrolysis tank for hydrolysis. The wastewater from the second neutralization reaction tank is then fed into the first hydrolysis tank for hydrolysis. Microorganisms in the first hydrolysis tank degrade large lipid molecules in the wastewater into small molecules. The wastewater treated in the first hydrolysis tank is then fed into the first A / O biochemical tank, where the microbial nitrification and denitrification processes degrade pollutants such as ammonia nitrogen, total nitrogen, and COD, producing a first biochemical liquid and a first biochemical sludge, respectively. The first biochemical liquid from the first A / O biochemical tank is then fed into the first MBR membrane reactor for ultrafiltration, producing a first MBR filtrate. In this step, the first biochemical liquid from the first A / O biochemical tank is then fed into the first MBR membrane reactor for ultrafiltration to intercept SS in the wastewater and ensure that the effluent SDI is less than 3, meeting the requirements for entry into the first multi-stage RO membrane reactor.

[0086] S5, RO reverse osmosis membrane concentration treatment

[0087] The first MBR filtrate is sent to the first multi-stage RO membrane reactor for reverse osmosis treatment to intercept pollutants in the wastewater and obtain the first fresh water and membrane concentrated water. The first fresh water is sent to the first recycled water tank for temporary storage.

[0088] In this step, the wastewater is degraded by the biochemical system, removing most of the pollutants, but the effluent still does not meet the reuse standards. Therefore, this application uses a first multi-stage RO membrane reactor to intercept pollutants such as ammonia nitrogen, total nitrogen, and COD in the wastewater, and the first fresh water enters the cooling tower for reuse.

[0089] S6, evaporation crystallization desalination

[0090] The membrane concentrated water produced by the first multi-stage RO membrane reactor is sent to the second MVR evaporation system for evaporation treatment to obtain the second evaporation condensate and the second evaporation mother liquor respectively. The second evaporation condensate produced by the second MVR evaporation system is returned to the second arsenic and silicon removal reaction tank for reuse.

[0091] After step S5, the resulting membrane concentrate contains an extremely high salt concentration. Therefore, this application utilizes MVR evaporation to meet the requirements of the back-end processing system. After processing in the second MVR evaporation system, the vast majority of the salt in the membrane concentrate is converted to solid salt, with only a small amount evaporating into the condensate. The condensate is then collected and slowly fed to the front-end system for arsenic treatment.

[0092] S7. Treatment of arsenic-containing sludge

[0093] The first batch sludge produced by the first wastewater batch tank, the second flotation sludge produced by the second flotation device, the second flocculation sludge produced by the second coagulation sedimentation tank, and the first biochemical sludge produced by the first A / O biochemical tank can be respectively put into the third arsenic-containing sludge tank for temporary storage.

[0094] After the sludge in the third arsenic-containing sludge tank reaches a specified volume, the sludge is dehydrated using a third filter press dewatering device to produce a third filter press filtrate and third filter press sludge. The third filter press filtrate produced by the third filter press dewatering device is returned to the second wastewater regulating tank for reuse.

[0095] In this embodiment, wastewater is treated by coagulation and sedimentation, which produces a certain amount of sludge, which is sent to a third arsenic-containing sludge pool for storage. After the sludge is stored to a certain amount, a filter press is used to dehydrate the sludge, and after the sludge moisture content is reduced to 80%, it is sent to a third party for proper treatment.

[0096] In summary, the scheme of the present application is a kind of zero emission scheme, which includes RO membrane and evaporation treatment, so the blockage of calcium and magnesium ions to membrane and evaporation must be considered emphatically, reducing system blockage, reducing system cleaning, and improving system stability. Since the main water source of cooling tower drainage is tap water, the conventional hardness of tap water is about 100-200mg / L. After naturally concentrating 4-6 times through the cooling tower, the hardness reaches 500-1000mg / L. After the first-level RO membrane is concentrated, the hardness of the wastewater reaches 2000-4000mg / L (converting calcium ion concentration to 800-1600mg / L), containing certain sulfate radical in the wastewater, calcium sulfate (calcium sulfate solubility is about 2000mg / L, converting calcium ion to about 600mg / L) will be formed, causing membrane system scaling to be serious. At the same time, such high concentration of calcium ions, after evaporation treatment, calcium ion concentration will further increase, causing the evaporation system to be seriously blocked, and evaporation efficiency is greatly reduced. Therefore, the inventors added carbonic acid to the front section of the arsenic-containing wastewater and controlled the pH value to remove calcium and magnesium ions from the wastewater. At the same time, the evaporation system discharged the mother liquor, reducing the system stability problems and cleaning frequency caused by scaling. Furthermore, the present application uses the method of adding scale inhibitors to increase the solubility of calcium and magnesium ions and reduce the risk of scaling. At the same time, the evaporation system mother liquor is sent to the front-end wastewater regulating tank for treatment in small quantities and multiple times, reducing the accumulation of calcium and magnesium ions in the evaporation system, controlling the calcium and magnesium ions within a certain range, and reducing the cleaning frequency of the evaporation system.

[0097] The water quality at different stages was measured, and the results are shown in Tables 2 and 3 below.

[0098] Table 2

[0099]

[0100] Table 3

[0101]

[0102] In Table 2, the meaning of arsenic-containing and fluorine-containing wastewater S-2023-712-4 is as follows: arsenic-containing and fluorine-containing wastewater refers to the arsenic-containing and fluorine-containing wastewater raw water to be treated, and S-2023-712-4 refers to the sample number; the meaning of arsenic-containing and fluorine-containing treated wastewater S-2023-712-7 is as follows: arsenic-containing and fluorine-containing treated wastewater refers to the supernatant obtained after treatment in the arsenic-containing and fluorine-containing sequencing batch reaction tank, and S-2023-712-7 refers to the sample number.

[0103] In Table 3, the meaning of arsenic-containing wastewater S-2023-712-3 is as follows: arsenic-containing wastewater refers to the arsenic-containing wastewater raw water to be treated, and S-2023-712-3 refers to the sample number; the meaning of recycled water S-2023-712-6 is as follows: recycled water refers to the recycled water temporarily stored in the first recycled water tank.

[0104] The experimental results show that this application has the following advantages:

[0105] (1) This application designs the process for key control indicators based on the principle of gradation process to ensure that the wastewater treatment meets the discharge standards;

[0106] (2) According to the characteristics of optoelectronic chip wastewater, different treatment processes are combined to make the entire sewage treatment system scientific, reasonable and compact;

[0107] (3) Regarding the harmful substance arsenic, this application adopts a multi-stage insurance measure of "multi-stage treatment + A / O + MBR + RO membrane + MVR evaporation device" to improve the system's ability to cope with fluctuations in incoming water quality and quantity, ensuring that the arsenic in the effluent meets the standard;

[0108] (4) This application adopts a small amount of mother liquor reflux method to solve the problem of SS blocking the evaporator, while reducing the concentration of evaporated organic matter and improving the stability of the evaporation system;

[0109] (5) The treatment process of the present application can achieve zero discharge of optoelectronic chip wastewater, and the wastewater treatment system can achieve "zero discharge" and meet the reuse standards. It can not only reduce the amount of external water and operating costs of the entire treatment system, but also increase the safety and stability of the wastewater treatment system, which has significant progressive significance.

[0110] In summary, the process of this application is reasonable and can effectively solve the problems of crystallization blockage and difficult precipitation of optoelectronic chip wastewater. It can also save water and ensure that the treated wastewater meets the enterprise reuse standards. It has significant economic and environmental value and is of practical significance for promoting the development of optoelectronic chips.

[0111] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A comprehensive zero-discharge treatment method for optoelectronic chip wastewater, characterized in that: Arsenic and fluorine-containing wastewater is the wastewater from the acid mist spray tower in the gallium arsenide production process. Arsenic-containing wastewater includes polishing wastewater, slicing wastewater and cooling tower wastewater. The steps include: S1. Defluorination precipitation treatment of arsenic and fluorine-containing wastewater Arsenic-containing and fluorine-containing wastewater is sent to the first wastewater regulating tank (1) for temporary storage; a sequencing batch treatment method is adopted to send the arsenic-containing and fluorine-containing wastewater temporarily stored in the first wastewater regulating tank (1) to the first wastewater sequencing batch tank (2), and alkali is added through the first alkali adding device to adjust the pH value of the wastewater in the first wastewater sequencing batch tank (2) to 7.5-8.0, and then a defluoridating agent is added to the first wastewater sequencing batch tank (2) through the first defluoridating agent adding device to reduce the fluoride ion concentration of the wastewater in the first wastewater sequencing batch tank (2) to below 1 mg / L, and then flocculants PAC and PAM are added to the first wastewater sequencing batch tank (2) in sequence through the first PAC and PAM adding devices for coagulation and sedimentation, and a first sequencing batch supernatant and a first sequencing batch sludge are obtained respectively; S2. Flotation treatment of arsenic-containing wastewater The arsenic-containing wastewater is sent to the second wastewater regulating tank (3) for temporary storage; the arsenic-containing wastewater is sent to the second flotation device (4) for flotation treatment. During the flotation process, alkali solution is added to the second flotation device (4) through the second alkali solution adding device and the pH value of the wastewater in the second flotation device (4) is adjusted to 10-11. PAC and PAM are then added to the second flotation device (4) through the second PAC and PAM adding device, and SS and oil substances in the wastewater are removed by flotation, thereby obtaining a second flotation liquid and a second flotation sludge respectively. S3. Pretreatment of arsenic-containing wastewater The second flotation liquid generated by the second flotation device (4) is sent to the second arsenic and silicon removal reaction tank (5) for treatment, iron salt is added to the second arsenic and silicon removal reaction tank (5) through the second iron salt adding device, and then a destabilizing agent is added to the second arsenic and silicon removal reaction tank (5) through the second destabilizing agent adding device, and finally sodium carbonate is added through the second sodium carbonate adding device to achieve arsenic and silicon removal and hardness removal treatment; The wastewater treated in the second arsenic and silicon removal reaction tank (5) flows into the second coagulation and sedimentation tank (6) by gravity; in the second coagulation and sedimentation tank (6), flocculants PAC and PAM are added through the fourth PAC and PAM adding device to perform coagulation and sedimentation, effectively adsorbing the co-precipitates of ferric arsenate and silicon formed in the wastewater; at the same time, SS in the wastewater is coagulated with the flocculants to form alum flowers, and then the mud and water are separated by natural sedimentation, and the second flocculated sludge and the second flocculated supernatant are obtained respectively; The second flocculated supernatant produced in the second coagulation sedimentation tank (6) enters the second neutralization reaction tank (7); in the second neutralization reaction tank (7), acid is added through the second acid adding device to perform a neutralization reaction; S4. Hydrolysis and biochemical treatment The supernatant of the first batch after treatment in the first wastewater batch tank (2) is sent to the first hydrolysis tank (8) for hydrolysis, and the wastewater after treatment in the second neutralization reaction tank (7) is sent to the first hydrolysis tank (8) for hydrolysis; under the action of microorganisms in the first hydrolysis tank (8), the macromolecular lipid substances in the wastewater are degraded; the wastewater treated in the first hydrolysis tank (8) is then sent to the first A / O biochemical tank (9), and the pollutants in the wastewater are degraded by the nitrification and denitrification of microorganisms, and a first biochemical liquid and a first biochemical sludge are obtained respectively; The first biochemical liquid produced by the first A / O biochemical pool (9) flows by gravity into the first MBR membrane reactor (10) for ultrafiltration treatment to obtain a first MBR filtrate; S5, RO reverse osmosis membrane concentration treatment The first MBR filtrate is sent to the first multi-stage RO membrane reactor (11) for reverse osmosis treatment to intercept pollutants in the wastewater and obtain first fresh water and membrane concentrated water; the first fresh water is sent to the first recycled water tank (12) for temporary storage; S6, evaporation crystallization desalination The membrane concentrate produced by the first multi-stage RO membrane reactor (11) is fed into the second MVR evaporation system (13) for evaporation and crystallization, and a second evaporation condensate and a second evaporation mother liquor are obtained respectively. The second evaporation condensate produced by the second MVR evaporation system (13) is returned to the second arsenic and silicon removal reaction tank (5) for further treatment. S7. Treatment of arsenic-containing sludge The first batch sludge produced by the first wastewater batch tank (2), the second flotation sludge produced by the second flotation device (4), the second flocculation sludge produced by the second coagulation sedimentation tank (6), and the first biochemical sludge produced by the first A / O biochemical tank (9) are respectively put into the third arsenic-containing sludge tank (14) for temporary storage; After the sludge in the third arsenic-containing sludge pool (14) reaches a specified amount, the sludge is dehydrated using a third filter press dehydration device (15) to obtain a third filter press filtrate and a third filter press sludge; Returning the third filter press filtrate produced by the third filter press dehydration device (15) to the second wastewater regulating tank (3) for further treatment; The acid liquid added by the second acid liquid adding device is an inorganic acid.

2. The processing method according to claim 1, characterized in that: In step S3, the ratio of the amount of the added iron ions to the amount of the arsenic ions in the sewage is ≥20.

3. The processing method according to claim 1, characterized in that: The acid added by the second acid adding device is hydrochloric acid or sulfuric acid.

4. The processing method according to any one of claims 1 to 3, characterized in that: In step S4, the first biochemical liquid produced by the first A / O biochemical pool (9) is then sent to the first MBR membrane reactor (10) for ultrafiltration treatment to intercept SS in the wastewater and ensure that the effluent SDI is less than 3.

5. The processing method according to claim 1, characterized in that: In step S5, the first fresh water in the first recycled water tank (12) is sent to the cooling tower for use as make-up water.

6. A zero-discharge integrated treatment device for optoelectronic chip wastewater according to the method of any one of claims 1 to 5, comprising a first wastewater regulating tank (1), a first wastewater sequencing batch tank (2), a first hydrolysis tank (8), a first A / O biochemical tank (9), a first MBR membrane reactor (10), a first multi-stage RO membrane reactor (11), a first recycled water tank (12), a second wastewater regulating tank (3), a second flotation device (4), a second arsenic and silicon removal reaction tank (5), a second coagulation and sedimentation tank (6), a second neutralization reaction tank (7), a second MVR evaporation system (13), a third arsenic-containing sludge tank (14), a third filter press dehydration device (15), a first alkali solution adding device, a first defluoridant adding device, a first PAC and PAM adding device, a second alkali solution adding device, a second PAC and PAM adding device, a second iron salt adding device, a second destabilizer adding device, a second sodium carbonate adding device, a fourth PAC and PAM adding device, and a second acid solution adding device; The first alkali solution adding device is connected to the first wastewater batch tank (2) and the first alkali solution adding device adds alkali solution into the first wastewater batch tank (2); the first defluoridation agent adding device is connected to the first wastewater batch tank (2) and the first defluoridation agent adding device adds defluoridation agent into the first wastewater batch tank (2); the first PAC and PAM adding device is connected to the first wastewater batch tank (2) and the first PAC and PAM adding device adds PAC and PAM into the first wastewater batch tank (2); The first wastewater regulating tank (1) is connected to the first wastewater sequencing batch tank (2), and the wastewater after being homogenized and uniformly treated in the first wastewater regulating tank (1) enters the first wastewater sequencing batch tank (2) to obtain a first sequencing batch supernatant and a first sequencing batch sludge respectively; The first wastewater sequencing batch tank (2) is connected to the first hydrolysis tank (8), and the first sequencing batch supernatant generated by the first wastewater sequencing batch tank (2) is sent to the first hydrolysis tank (8). The first hydrolysis tank (8) is connected to the first A / O biochemical tank (9), and the wastewater treated by the first hydrolysis tank (8) enters the first A / O biochemical tank (9) for biochemical treatment and obtains a first biochemical liquid and a first biochemical sludge respectively. The first A / O biochemical tank (9) is connected to the first MBR membrane reactor (10), and the first biochemical liquid treated by the first A / O biochemical tank (9) enters the first MBR membrane reactor (11). Filtration is performed in an MBR membrane reactor (10) to obtain a first MBR filtrate, the first MBR membrane reactor (10) is connected to a first multi-stage RO membrane reactor (11), and the first MBR filtrate filtered by the first MBR membrane reactor (10) enters the first multi-stage RO membrane reactor (11) for reverse osmosis treatment to obtain first fresh water and membrane concentrated water, the first multi-stage RO membrane reactor (11) is connected to a first recycled water tank (12), and the first fresh water treated by the first multi-stage RO membrane reactor (11) is sent to the first recycled water tank (12) for temporary storage; The second alkali solution adding device is connected to the second flotation device (4) and the second alkali solution adding device adds alkali solution into the second flotation device (4); the second PAC and PAM adding device is connected to the second flotation device (4) and the second PAC and PAM adding device adds PAC and PAM into the second flotation device (4); the second wastewater regulating tank (3) is connected to the second flotation device (4) and the wastewater in the second wastewater regulating tank (3) enters the second flotation device (4) for treatment to obtain a second flotation liquid and a second flotation sludge respectively; The second flotation device (4) is connected to the second arsenic removal and silicon removal reaction tank (5), and the second flotation liquid treated by the second flotation device (4) enters the second arsenic removal and silicon removal reaction tank (5) for treatment. The second iron salt adding device is connected to the second arsenic removal and silicon removal reaction tank (5), and the second iron salt adding device adds iron salt to the second arsenic removal and silicon removal reaction tank (5). The second destabilizing agent adding device is connected to the second arsenic removal and silicon removal reaction tank (5), and the second destabilizing agent adding device adds destabilizing agent to the second arsenic removal and silicon removal reaction tank (5). The second sodium carbonate adding device is connected to the second arsenic removal and silicon removal reaction tank (5), and the second sodium carbonate adding device adds sodium carbonate to the second arsenic removal and silicon removal reaction tank (5). The second arsenic and silicon removal reaction tank (5) is connected to the second coagulation and sedimentation tank (6), and the wastewater treated by the second arsenic and silicon removal reaction tank (5) enters the second coagulation and sedimentation tank (6) for treatment, and the fourth PAC and PAM adding device is connected to the second coagulation and sedimentation tank (6), and the fourth PAC and PAM adding device adds PAC and PAM to the second coagulation and sedimentation tank (6) to obtain a second flocculated sludge and a second flocculated supernatant, respectively; The second coagulation sedimentation tank (6) is connected to the second neutralization reaction tank (7), and the second flocculation supernatant liquid treated in the second coagulation sedimentation tank (6) enters the second neutralization reaction tank (7), and the second acid liquid adding device is connected to the second neutralization reaction tank (7), and the second acid liquid adding device adds acid liquid into the second neutralization reaction tank (7) to neutralize the second flocculation supernatant liquid; The second neutralization reaction tank (7) is connected to the first hydrolysis tank (8), and the wastewater treated by the second neutralization reaction tank (7) enters the first hydrolysis tank (8) for hydrolysis; The first multi-stage RO membrane reactor (11) is connected to the second MVR evaporation system (13), and the membrane concentrated water produced by the first multi-stage RO membrane reactor (11) enters the second MVR evaporation system (13) for evaporation treatment to obtain a second evaporation condensate and a second evaporation mother liquor, respectively; the second MVR evaporation system (13) is connected to the second arsenic and silicon removal reaction tank (5), and the second evaporation condensate produced by the second MVR evaporation system (13) returns to the second arsenic and silicon removal reaction tank (5); The first wastewater sequencing batch tank (2), the second air flotation device (4), the second coagulation sedimentation tank (6), and the first A / O biochemical tank (9) are respectively connected to the third arsenic-containing sludge tank (14), and the first sequencing batch sludge generated by the first wastewater sequencing batch tank (2), the second air flotation sludge generated by the second air flotation device (4), the second flocculation sludge generated by the second coagulation sedimentation tank (6), and the first biochemical sludge generated by the first A / O biochemical tank (9) are respectively entered into the third arsenic-containing sludge tank (14) for temporary storage; The third arsenic-containing sludge pool (14) is connected to the third filter press dewatering device (15), and the sludge in the third arsenic-containing sludge pool (14) enters the third filter press dewatering device (15) for filter press treatment to obtain a third filter press filtrate and a third filter press sludge, respectively. The third filter press dewatering device (15) is connected to the second wastewater regulating tank (3), and the third filter press filtrate generated by the third filter press dewatering device (15) is returned to the second wastewater regulating tank (3) for reuse.

Images