Method for efficiently recovering and treating heavy metals in tin-containing wastewater

Abstract

The invention discloses a method for efficiently recovering and treating heavy metals in tin-containing wastewater, belongs to the field of comprehensive treatment of tin-containing wastewater of circuit boards, and particularly relates to a method for efficiently recovering and treating heavy metals in tin-containing wastewater. The invention aims to solve the problems of high treatment difficulty, high treatment cost, complex treatment process and the like of the existing tin-containing wastewater. The method comprises the following steps: feeding the tin-containing wastewater into the tin-containing wastewater pH regulating tank for pH regulation, feeding the regulated tin-containing wastewater into the coagulative precipitation tank, adding sodium carbonate solid, mixing, adding a coagulant, and standing for precipitation to obtain tin-containing co-precipitation floc and tin-ion-removed wastewater; feeding the tin-ion-removed wastewater into a sulfur circulation multi-stage anaerobic biological treatment reactor for complexing and settling heavy metals and removing pollutants, so as to obtain anaerobic sludge containing the heavy metals and supernate; supernate is fed into a sand filter for filtering treatment, and sewage subjected to sand filtration is discharged through a sewage discharge pipeline. The method is used for removing and recycling the heavy metals in the tin-containing wastewater.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive treatment of tin-containing wastewater from circuit boards, and specifically relates to a method for efficiently recovering and treating heavy metals in tin-containing wastewater. Background Art

[0002] Environmental pollution mainly comes from daily life and industrial production. Among them, industrial production has become one of the main causes of environmental pollution due to its complex composition, high content, high output and some difficulty in decomposition of pollutants. As one of the main wastewaters in the printed circuit board industry, tin-containing wastewater has a large amount of waste generated, contains a small amount of tin, iron, copper and a large amount of nitric acid and a variety of organic additives, has the characteristics of high free acidity and complex composition, and has difficult treatment technology, high cost of treatment, and great destructiveness to the environment. If improperly treated, it will cause serious environmental pollution.

[0003] At present, the treatment of tin-containing wastewater at home and abroad mainly adopts composite treatment technologies such as physical evaporation, ion exchange and membrane separation, and the treatment process varies according to the actual situation. Physical evaporation method for treating tin-containing wastewater includes natural evaporation, mechanical compression evaporation, multi-effect evaporation and other methods and technologies; membrane separation technology has the advantages of strong adaptability and good selectivity, but the membrane is easy to clog and corrode, needs to be replaced frequently, and has high cost; ion exchange technology is that ions in tin-containing wastewater exchange reaction with fixed anions or cations in ion exchange column. After the tin-containing wastewater passes through the anion and cation exchange column, cations such as sodium ions are replaced by hydrogen ions, and anions such as chloride ions are replaced by hydroxide ions. Finally, anions and cations are left in the ion exchange column to achieve the purpose of desalination. This method has the disadvantages of easy clogging of exchange resin, high regeneration cost, and difficult waste treatment after exchange. Compared with physical and chemical degradation technology, activated sludge biodegradation has the characteristics of high efficiency, thoroughness, no secondary pollution, low construction and operation cost, simple structure, and strong impact load resistance. Summary of the invention

[0004] The invention provides a method for efficiently recovering and treating heavy metals in tin-containing wastewater in order to solve the problems of great difficulty in treating existing tin-containing wastewater, high treatment cost and complex treatment process.

[0005] The method for efficiently recovering and treating heavy metals in tin-containing wastewater of the present invention is specifically carried out according to the following steps:

[0006] 1. Construct a coagulation-precipitation-sulfur cycle heavy metal biological treatment technology combination component consisting of a tin-containing wastewater collection tank, a tin-containing wastewater pH adjustment tank, a coagulation sedimentation tank, a sulfur cycle multi-stage anaerobic biological treatment reactor and a sand filter; the water outlet of the tin-containing wastewater collection tank is connected to the water inlet of the tin-containing wastewater pH adjustment tank, the water outlet of the tin-containing wastewater pH adjustment tank is connected to the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank is connected to the water inlet of the sulfur cycle multi-stage anaerobic biological treatment reactor, and the water outlet of the sulfur cycle multi-stage anaerobic biological treatment reactor is connected to the water inlet of the sand filter; the bottom of the coagulation sedimentation tank is provided with a discharge port, and the sand filter is provided with a sewage pipe;

[0007] 2. The tin-containing wastewater is sent to a tin-containing wastewater collection tank for storage through a peristaltic pump, and the tin-containing wastewater is sent to a tin-containing wastewater pH adjustment tank for pH adjustment. The adjusted tin-containing wastewater is sent to a coagulation sedimentation tank, sodium carbonate solid is added, and the mixture is fully stirred for 20 to 30 minutes. A coagulant is then added thereto, and stirred for 20 to 30 minutes, and then the mixture is allowed to settle for 1 to 2 hours to obtain tin-containing coprecipitated flocs and wastewater with tin ions removed.

[0008] 3. Remove the tin ions and send the wastewater to the sulfur cycle multi-stage anaerobic biological treatment reactor for heavy metal complexation sedimentation and pollutant removal to obtain anaerobic sludge and supernatant containing heavy metals;

[0009] 4. The supernatant is sent to the sand filter tank for filtration, and the wastewater after sand filtration is discharged through the sewage pipe.

[0010] Beneficial effects of the present invention:

[0011] The present invention proposes a method for removing tin ions and other metal ions in wastewater by combining coagulation-precipitation-sulfur cycle heavy metal biological treatment technology. The coagulation-precipitation-sulfur cycle heavy metal biological adsorption is simple and convenient to operate, has low treatment cost, and a large amount of treated water. It can not only improve the removal rate of tin, but also reduce the amount of sludge generated. It is an economical and practical method for treating tin-containing wastewater. The present invention provides a new feasible solution for improving the removal of heavy metals in tin-containing wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of a process flow for a method for efficiently recovering and treating heavy metals in tin-containing wastewater;

[0013] Figure 2 This is a schematic diagram of the structure of a sulfur cycle multi-stage anaerobic biological treatment reactor. DETAILED DESCRIPTION

[0014] Specific implementation method 1: This implementation method is a method for efficiently recovering heavy metals from tin-containing wastewater, which is specifically carried out according to the following steps:

[0015] 1. Construct a coagulation-precipitation-sulfur cycle heavy metal biological treatment technology combination component consisting of a tin-containing wastewater collection tank, a tin-containing wastewater pH adjustment tank, a coagulation sedimentation tank, a sulfur cycle multi-stage anaerobic biological treatment reactor and a sand filter; the water outlet of the tin-containing wastewater collection tank is connected to the water inlet of the tin-containing wastewater pH adjustment tank, the water outlet of the tin-containing wastewater pH adjustment tank is connected to the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank is connected to the water inlet of the sulfur cycle multi-stage anaerobic biological treatment reactor, and the water outlet of the sulfur cycle multi-stage anaerobic biological treatment reactor is connected to the water inlet of the sand filter; the bottom of the coagulation sedimentation tank is provided with a discharge port, and the sand filter is provided with a sewage pipe;

[0016] 2. The tin-containing wastewater is sent to a tin-containing wastewater collection tank for storage through a peristaltic pump, and the tin-containing wastewater is sent to a tin-containing wastewater pH adjustment tank for pH adjustment. The adjusted tin-containing wastewater is sent to a coagulation sedimentation tank, sodium carbonate solid is added, and the mixture is fully stirred for 20 to 30 minutes. A coagulant is then added thereto, and stirred for 20 to 30 minutes, and then the mixture is allowed to settle for 1 to 2 hours to obtain tin-containing coprecipitated flocs and wastewater with tin ions removed.

[0017] 3. Remove the tin ions and send the wastewater to the sulfur cycle multi-stage anaerobic biological treatment reactor for heavy metal complexation sedimentation and pollutant removal to obtain anaerobic sludge and supernatant containing heavy metals;

[0018] 4. The supernatant is sent to the sand filter tank for filtration, and the wastewater after sand filtration is discharged through the sewage pipe.

[0019] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that the pH adjustment of the pH adjustment tank for tin-containing wastewater in step 2 is automatically controlled, the alkali solution is 5-20% sodium hydroxide, and the pH of the tin-containing wastewater is controlled to be 7-8. Others are the same as specific embodiment 1.

[0020] Specific implementation method 3: This implementation method is different from specific implementation method 1 in that: the addition amount of the sodium carbonate solid in step 2 is 25-50 mg / L; the coagulant is polyaluminium chloride PAC coagulant, and the addition amount is 8-20 mg / L. The rest is the same as specific implementation method 1.

[0021] In this embodiment, solid sodium carbonate is added to convert tin ions into stannous hydroxide to fix free tin ions in water.

[0022] Specific embodiment 4: This embodiment is different from specific embodiment 1 in that: the sulfur cycle multi-stage anaerobic biological treatment reactor in step 3 is composed of an ABR reactor and an aerobic aeration tank connected in series, and the ABR reactor is divided into three anaerobic zones and one facultative zone; the reaction zone volume of the ABR reactor is 90L, and the reaction zone volume of the aerobic aeration tank is 70L. Others are the same as specific embodiment 1.

[0023] The sulfur cycle multi-stage anaerobic biological treatment reactor of this embodiment mainly uses sulfur metabolism through the control of multi-stage anaerobic and facultative aerobic conditions. While using multi-stage anaerobic to strengthen sulfur reduction and oxidation to further achieve complex sedimentation of heavy metals in wastewater, it can also complete the removal of pollutants such as organic matter and ammonia nitrogen. Fillers are used in the aerobic zone to increase the contact area of ​​microorganisms and enhance the ability to remove pollutants.

[0024] Specific implementation method 5: This implementation method is different from specific implementation method 4 in that the hydraulic retention time of the anaerobic zone, the facultative zone and the aerobic aeration tank are 16h:8h:8h respectively. The rest is the same as specific implementation method 4.

[0025] Specific embodiment 6: This embodiment is different from specific embodiment 4 in that the inoculated sludge of the sulfur cycle multi-stage anaerobic biological treatment reactor comes from the Nansha sewage treatment plant, and is inoculated into the sulfur cycle multi-stage anaerobic biological treatment reactor after cultivation, and the sludge concentration is 3500-7000 mg / L. Others are the same as specific embodiment 4.

[0026] Specific embodiment 7: This embodiment differs from specific embodiment 6 in that: the aerobic aeration tank is equipped with polyethylene porous filler and part of the wastewater in the aerobic aeration tank is returned to the facultative zone of the ABR reactor, and the return rate is 40%; the packing density of the polyethylene porous filler is 60%, and 10L of seeding sludge is inoculated on the polyethylene porous filler. The rest is the same as specific embodiment 6.

[0027] Specific embodiment eight: This embodiment differs from specific embodiment six in that the inoculated sludge is cultured with organic carbon source, sulfate, and persulfate as substrates. Other aspects are the same as specific embodiment six.

[0028] The sludge cultured in this embodiment has good sulfate reduction and denitrification capabilities.

[0029] Specific embodiment 9: This embodiment is different from the specific embodiment 1 in that: quartz sand, activated carbon particles and manganese sand particles are arranged in the sand filter; the quartz sand particle size is 0.5-1.2 mm and the height is 0.5 m; the activated carbon particle size is 0.5-1.5 mm and the height is 0.5 m; the manganese sand particle size is 0.3-1.0 mm and the height is 0.5 m. The rest is the same as the specific embodiment 1.

[0030] The purpose of this embodiment is to further filter the odor, color, suspended matter, microorganisms, and sludge particles in the water so as to meet the discharge standards.

[0031] Specific embodiment 10: This embodiment differs from specific embodiment 1 in that the tin-containing coprecipitated flocs and the anaerobic sludge containing heavy metals are sent to the heavy metal sludge recovery device, and the heavy metal ions therein are recovered after purification, drying, incineration, and slag removal. The rest is the same as specific embodiment 1.

[0032] This embodiment recovers heavy metal ions through purification, drying, incineration, slagging and other steps, which not only reduces the treatment cost of hazardous wastes of enterprises, but also further improves the resource utilization rate in the treatment process.

[0033] The following examples are used to verify the beneficial effects of the present invention:

[0034] Embodiment 1: A method for efficiently recovering heavy metals from tin-containing wastewater is specifically carried out according to the following steps:

[0035] 1. Construct a coagulation-precipitation-sulfur cycle heavy metal biological treatment technology combination component consisting of a tin-containing wastewater collection tank, a tin-containing wastewater pH adjustment tank, a coagulation sedimentation tank, a sulfur cycle multi-stage anaerobic biological treatment reactor and a sand filter; the water outlet of the tin-containing wastewater collection tank is connected to the water inlet of the tin-containing wastewater pH adjustment tank, the water outlet of the tin-containing wastewater pH adjustment tank is connected to the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank is connected to the water inlet of the sulfur cycle multi-stage anaerobic biological treatment reactor, and the water outlet of the sulfur cycle multi-stage anaerobic biological treatment reactor is connected to the water inlet of the sand filter; the bottom of the coagulation sedimentation tank is provided with a discharge port, and the sand filter is provided with a sewage pipe;

[0036] 2. The tin-containing wastewater is sent to the tin-containing wastewater collection tank for storage through a peristaltic pump, and the tin-containing wastewater is sent to the tin-containing wastewater pH adjustment tank for pH adjustment. The adjusted tin-containing wastewater is sent to the coagulation sedimentation tank, sodium carbonate solid is added and fully stirred for 30 minutes, and then a coagulant is added thereto and stirred for 20 minutes, and then allowed to settle for 1 hour to obtain tin-containing coprecipitated flocs and tin ion-removed wastewater; the tin-containing wastewater comes from a circuit board production factory in Jiangmen City, Guangdong Province, with an initial pH value of 5.5, a COD of 3400 mg / L, a tin ion concentration of 20.1 mg / L, and an iron ion concentration of 11 .8mg / L, copper ion concentration is 2.23mg / L; the pH adjustment of the pH adjustment tank for tin-containing wastewater is automatically controlled, the alkali solution is 10% sodium hydroxide, and the pH of the tin-containing wastewater is controlled to be 7.5; the addition amount of the sodium carbonate solid is 35mg / L; the coagulant is polyaluminium chloride PAC coagulant, and the addition amount is 15mg / L; the inoculated sludge of the sulfur cycle multi-stage anaerobic biological treatment reactor comes from the Nansha sewage treatment plant in Guangzhou, and is inoculated into the sulfur cycle multi-stage anaerobic biological treatment reactor after cultivation, and the sludge concentration is 3500-7000mg / L;

[0037] 3. The wastewater after tin ion removal is sent to a sulfur cycle multi-stage anaerobic biological treatment reactor for heavy metal complexation precipitation and pollutant removal to obtain anaerobic sludge and supernatant containing heavy metals; the sulfur cycle multi-stage anaerobic biological treatment reactor is composed of an ABR reactor and an aerobic aeration tank connected in series, and the ABR reactor is divided into three anaerobic zones and one facultative zone; the reaction zone volume of the ABR reactor is 90L, and the reaction zone volume of the aerobic aeration tank is 70L; the hydraulic retention time of the anaerobic zone, the facultative zone and the aerobic aeration tank are 16h:8h:8h respectively; the aerobic aeration tank is equipped with polyethylene porous filler and part of the wastewater in the aerobic aeration tank is returned to the facultative zone of the ABR reactor, and the reflux rate is 40%; the filler density of the polyethylene porous filler is 60%, and 10L of inoculated sludge is inoculated on the polyethylene porous filler;

[0038] Fourth, the supernatant is sent to the sand filter for filtration treatment. The treatment time is 1 hour. The wastewater after sand filtration is discharged through the sewage pipe. Quartz sand, activated carbon particles and manganese sand particles are set in the sand filter. The quartz sand particle size is 0.5-1.2mm and the height is 0.5m; the activated carbon particle size is 0.5-1.5mm and the height is 0.5m; the manganese sand particle size is 0.3-1.0mm and the height is 0.5m. The tin concentration of the effluent from the sand filter is about 8μg / L, and the COD of the effluent is 68mg / L, which shows that this set of processes can effectively treat tin-containing wastewater.

Claims

1. A method for efficiently recovering heavy metals from tin-containing wastewater, characterized in that The method for efficiently recovering and treating heavy metals in tin-containing wastewater is specifically carried out according to the following steps:

1. Construct a coagulation-precipitation-sulfur cycle heavy metal biological treatment technology combination component consisting of a tin-containing wastewater collection tank, a tin-containing wastewater pH adjustment tank, a coagulation sedimentation tank, a sulfur cycle multi-stage anaerobic biological treatment reactor and a sand filter; the water outlet of the tin-containing wastewater collection tank is connected to the water inlet of the tin-containing wastewater pH adjustment tank, the water outlet of the tin-containing wastewater pH adjustment tank is connected to the water inlet of the coagulation sedimentation tank, the water outlet of the coagulation sedimentation tank is connected to the water inlet of the sulfur cycle multi-stage anaerobic biological treatment reactor, and the water outlet of the sulfur cycle multi-stage anaerobic biological treatment reactor is connected to the water inlet of the sand filter; the bottom of the coagulation sedimentation tank is provided with a discharge port, and the sand filter is provided with a sewage pipe; 2. The tin-containing wastewater is sent to a tin-containing wastewater collection tank for storage through a peristaltic pump, and the tin-containing wastewater is sent to a tin-containing wastewater pH adjustment tank for pH adjustment. The adjusted tin-containing wastewater is sent to a coagulation sedimentation tank, sodium carbonate solid is added, and the mixture is fully stirred for 20 to 30 minutes. A coagulant is then added thereto, and stirred for 20 to 30 minutes, and then the mixture is allowed to settle for 1 to 2 hours to obtain tin-containing coprecipitated flocs and wastewater with tin ions removed.

3. Remove the tin ions and send the wastewater to the sulfur cycle multi-stage anaerobic biological treatment reactor for heavy metal complexation sedimentation and pollutant removal to obtain anaerobic sludge and supernatant containing heavy metals; 4. The supernatant is sent to the sand filter tank for filtration, and the wastewater after sand filtration is discharged through the sewage pipe.

2. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 1, characterized in that The pH of the tin-containing wastewater pH adjustment tank in step 2 is automatically controlled, the alkali solution is 5-20% sodium hydroxide, and the pH of the tin-containing wastewater is controlled to be 7-8.

3. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 1, characterized in that In step 2, the amount of sodium carbonate solid added is 25-50 mg / L; the coagulant is polyaluminium chloride PAC coagulant, and the amount of addition is 8-20 mg / L.

4. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 1, characterized in that The sulfur cycle multi-stage anaerobic biological treatment reactor in step 3 is composed of an ABR reactor and an aerobic aeration tank connected in series. The ABR reactor is divided into three anaerobic zones and one facultative zone. The reaction zone volume of the ABR reactor is 90L, and the reaction zone volume of the aerobic aeration tank is 70L.

5. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 4, characterized in that The hydraulic retention time of the anaerobic zone, facultative zone and aerobic aeration tank are 16h:8h:8h respectively.

6. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 4, characterized in that The inoculated sludge of the sulfur cycle multi-stage anaerobic biological treatment reactor comes from the Nansha sewage treatment plant, and is inoculated into the sulfur cycle multi-stage anaerobic biological treatment reactor after being cultured, and the sludge concentration is 3500-7000 mg / L.

7. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 6, characterized in that The aerobic aeration tank is equipped with polyethylene porous filler and part of the wastewater in the aerobic aeration tank is returned to the facultative zone of the ABR reactor, with a return rate of 40%; the packing density of the polyethylene porous filler is 60%, and 10L of seeding sludge is inoculated on the polyethylene porous filler.

8. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 6, characterized in that The inoculated sludge is cultured with organic carbon source, sulfate and persulfate as substrates.

9. A method for efficiently recovering heavy metals from tin-containing wastewater according to claim 1, characterized in that Quartz sand, activated carbon particles and manganese sand particles are arranged in the sand filter; the quartz sand particle size is 0.5-1.2mm and the height is 0.5m; the activated carbon particle size is 0.5-1.5mm and the height is 0.5m; the manganese sand particle size is 0.3-1.0mm and the height is 0.5m.

10. The method for efficiently recovering heavy metals from tin-containing wastewater according to claim 1, characterized in that The tin-containing co-precipitated flocs and the anaerobic sludge containing heavy metals are sent to a heavy metal sludge recovery device, and the heavy metal ions therein are recovered after purification, drying, incineration and slag removal steps.

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