Method for removing heavy metals in circuit board wastewater

Abstract

The invention discloses a method for removing heavy metals in circuit board wastewater. The method comprises the following steps: step 1, pretreating wastewater; and 2, combining the treated wastewater, carrying out two-stage coagulating sedimentation, and removing and improving a biochemical system. According to the circuit board wastewater heavy metal removal method, wastewater pretreatment is adopted, cyanide-containing wastewater, nickel-containing wastewater and organic wastewater are treated respectively, then integrated comprehensive treatment is carried out, two-stage coagulating sedimentation and biochemical system removal improvement are carried out, and joint optimization and coordination improvement are carried out, so that the wastewater removal efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for removing heavy metals from circuit board wastewater. Background Art

[0002] Circuit board wastewater treatment includes the design of wastewater treatment process, electrical control, civil engineering and other aspects. The engineering design is a wastewater treatment station, from the regulating tank to the wastewater station discharge port, including wastewater treatment and sludge treatment. Circuit board wastewater treatment includes cyanide-containing wastewater, nickel-containing wastewater and other wastewater. Existing technologies make it difficult to achieve the coordinated removal of impurities such as heavy metals and COD, which limits the process removal efficiency. Summary of the Invention

[0003] In view of the defects of the prior art, the purpose of the present invention is to provide a method for removing heavy metals from circuit board wastewater to solve the problems raised in the above background technology.

[0004] The present invention solves the technical problem by adopting the following technical solutions: The present invention provides a method for removing heavy metals from circuit board wastewater, comprising the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The reaction principle is as follows: Primary oxidation: pH: 10-11 CN +ClO +H2O→CNCl+2OH

[0005] CNCl + 2OH-→CNO +Cl +H2O Secondary cyanide breaking: pH: 8~8.5 2CNO +3ClO +H2O→2CO ↑+N ↑+3Cl +2OH

[0006] This method is a mature cyanide destruction process. Cyanide destruction requires an appropriate pH range. pH adjustment is achieved using an industrial pH meter with automated alkali addition, and ORP-based oxidant addition. After cyanide destruction, the product is discharged into a phosphorus removal reaction tank for subsequent treatment.

[0007] The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0008] Preferably, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0009] Preferably, a combination of anaerobic and aerobic treatment is used in the biochemical system removal; Control the mixed liquor sludge concentration MLSS in the anoxic-aerobic tank to 5-6g / L, the temperature to 32-34℃, control the dissolved oxygen concentration in the anoxic zone to ≤0.5mg / L, and the dissolved oxygen concentration in the aerobic zone to 3L-4mg / .

[0010] Preferably, 35-40 mg / L of modified montmorillonite agent can be added to the two-stage coagulation sedimentation.

[0011] Preferably, the preparation method of the modified montmorillonite agent is: The montmorillonite is heat-treated at 150-170°C for 10-15 minutes, then cooled to 55°C at a rate of 1-3°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modification liquid and stirred for modification treatment. After the stirring is completed, the mixture is filtered and dried to obtain a modified montmorillonite agent.

[0012] Montmorillonite has a lamellar structure that can adsorb heavy metal ions. After thermal improvement treatment, its lamellar spacing and lamellar activity are optimized, thereby improving the removal of impurity ions. After further improvement and optimization with the modifying liquid, the hydroxyapatite in the modifying liquid has point adsorption, and the zeolite powder has adsorption properties. It is then blended and coordinated with sodium dodecylbenzenesulfonate solution, urea solution and silane coupling agent KH550, so that the improved modified montmorillonite agent optimizes the coordinated treatment effect of wastewater in the system.

[0013] Preferably, the stirring speed of the stirring modification is 550-750 r / min, and the stirring time is 1 hour.

[0014] Preferably, the preparation method of the modified liquid is: 2-5 parts of hydroxyapatite, 1-3 parts of zeolite powder, 5-8 parts of sodium dodecylbenzenesulfonate solution and 2-3 parts of urea solution are evenly mixed, and finally 2-3 parts of silane coupling agent KH550 are added. The mixture is ball-milled thoroughly and the ball-milling is completed to obtain a modified solution.

[0015] Preferably, the mass fraction of the sodium dodecylbenzenesulfonate solution is 2-5%; and the mass fraction of the urea solution is 3-5%.

[0016] Preferably, the ball milling is performed at a speed of 1000 r / min for 1 h.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts wastewater pretreatment to remove heavy metals from circuit board wastewater, and separately treats cyanide-containing wastewater, nickel-containing wastewater and organic wastewater, and then conducts integrated comprehensive treatment. Through two-stage coagulation and sedimentation, the regeneration system is improved and optimized and coordinated to improve the wastewater removal efficiency. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] A method for removing heavy metals from circuit board wastewater according to this embodiment includes the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0020] In this embodiment, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0021] The biochemical system of this embodiment adopts a combination of anaerobic and aerobic treatment; Control the mixed liquor sludge concentration MLSS in the anoxic-aerobic tank to 5-6g / L, the temperature to 32-34℃, control the dissolved oxygen concentration in the anoxic zone to ≤0.5mg / L, and the dissolved oxygen concentration in the aerobic zone to 3L-4mg / .

[0022] In the two-stage coagulation and sedimentation of this embodiment, 35-40 mg / L of modified montmorillonite agent can also be added.

[0023] The preparation method of the modified montmorillonite agent of this embodiment is: The montmorillonite is heat-treated at 150-170°C for 10-15 minutes, then cooled to 55°C at a rate of 1-3°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modification liquid and stirred for modification treatment. After the stirring is completed, the mixture is filtered and dried to obtain a modified montmorillonite agent.

[0024] The stirring speed of the stirring modification in this embodiment is 550-750 r / min, and the stirring time is 1 hour.

[0025] The preparation method of the modified liquid of this embodiment is: 2-5 parts of hydroxyapatite, 1-3 parts of zeolite powder, 5-8 parts of sodium dodecylbenzenesulfonate solution and 2-3 parts of urea solution are evenly mixed, and finally 2-3 parts of silane coupling agent KH550 are added. The mixture is ball-milled thoroughly and the ball-milling is completed to obtain a modified solution.

[0026] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 2-5%; the mass fraction of the urea solution is 3-5%.

[0027] The ball milling in this embodiment is sufficient at a ball milling speed of 1000 r / min for 1 hour.

[0028] Example 1. A method for removing heavy metals from circuit board wastewater according to this embodiment includes the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0029] In this embodiment, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0030] The biochemical system of this embodiment adopts a combination of anaerobic and aerobic treatment; The MLSS concentration of mixed liquor in the anoxic-aerobic tank is controlled to be 5 g / L, the temperature is 32°C, the dissolved oxygen concentration in the anoxic zone is controlled to be ≤0.5 mg / L, and the dissolved oxygen concentration in the aerobic zone is controlled to be 3L-4 mg / .

[0031] In the two-stage coagulation and sedimentation of this embodiment, 35 mg / L of modified montmorillonite agent can also be added.

[0032] The preparation method of the modified montmorillonite agent of this embodiment is: The montmorillonite is heat-treated at 150°C for 10 minutes, then cooled to 55°C at a rate of 1°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modifying liquid and stirred for modification treatment. After the stirring is completed, the modified montmorillonite agent is filtered and dried to obtain the modified montmorillonite agent.

[0033] The stirring speed of the stirring modification in this embodiment is 550 r / min, and the stirring time is 1 hour.

[0034] The preparation method of the modified liquid of this embodiment is: 2 parts of hydroxyapatite, 1 part of zeolite powder, 5 parts of sodium dodecylbenzenesulfonate solution and 2 parts of urea solution were evenly mixed, and finally 2 parts of silane coupling agent KH550 were added. The mixture was ball-milled thoroughly and the ball-milling was completed to obtain a modified solution.

[0035] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 2%; the mass fraction of the urea solution is 3%.

[0036] The ball milling in this embodiment is sufficient at a ball milling speed of 1000 r / min for 1 hour.

[0037] Example 2. A method for removing heavy metals from circuit board wastewater according to this embodiment includes the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0038] In this embodiment, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0039] The biochemical system of this embodiment adopts a combination of anaerobic and aerobic treatment; The mixed liquor sludge concentration MLSS in the anoxic-aerobic tank was controlled to be 6 g / L, the temperature was controlled to be 34°C, the dissolved oxygen concentration in the anoxic zone was controlled to be ≤0.5 mg / L, and the dissolved oxygen concentration in the aerobic zone was controlled to be 4 mg / L.

[0040] In the two-stage coagulation and sedimentation of this embodiment, 40 mg / L of modified montmorillonite agent can also be added.

[0041] The preparation method of the modified montmorillonite agent of this embodiment is: The montmorillonite is heat-treated at 170°C for 15 minutes, then cooled to 55°C at a rate of 3°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modifying liquid and stirred for modification treatment. After the stirring is completed, the modified montmorillonite agent is filtered and dried to obtain the modified montmorillonite agent.

[0042] The stirring speed of the stirring modification in this embodiment is 750 r / min, and the stirring time is 1 hour.

[0043] The preparation method of the modified liquid of this embodiment is: 5 parts of hydroxyapatite, 3 parts of zeolite powder, 8 parts of sodium dodecylbenzenesulfonate solution and 3 parts of urea solution were evenly mixed, and finally 3 parts of silane coupling agent KH550 were added and ball milled thoroughly. After the ball milling was completed, a modified solution was obtained.

[0044] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 5%; the mass fraction of the urea solution is 5%.

[0045] The ball milling in this embodiment is sufficient at a ball milling speed of 1000 r / min for 1 hour.

[0046] Example 3. A method for removing heavy metals from circuit board wastewater according to this embodiment includes the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0047] In this embodiment, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0048] The biochemical system of this embodiment adopts a combination of anaerobic and aerobic treatment; The MLSS concentration of the mixed liquor in the anoxic-aerobic tank was controlled to be 5.5 g / L, the temperature was 33°C, the dissolved oxygen concentration in the anoxic zone was controlled to be ≤0.5 mg / L, and the dissolved oxygen concentration in the aerobic zone was controlled to be 3.5 mg / L.

[0049] In the two-stage coagulation and sedimentation of this embodiment, 37.5 mg / L of modified montmorillonite agent can also be added.

[0050] The preparation method of the modified montmorillonite agent of this embodiment is: The montmorillonite is heat-treated at 160°C for 12.5 minutes, then cooled to 55°C at a rate of 2°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modifying liquid and stirred for modification treatment. After the stirring is completed, the modified montmorillonite agent is filtered and dried to obtain the modified montmorillonite agent.

[0051] The stirring speed of the stirring modification in this embodiment is 600 r / min, and the stirring time is 1 hour.

[0052] The preparation method of the modified liquid of this embodiment is: 3.5 parts of hydroxyapatite, 2 parts of zeolite powder, 6.5 parts of sodium dodecylbenzenesulfonate solution and 2.5 parts of urea solution were evenly mixed, and finally 2.5 parts of silane coupling agent KH550 were added and ball milled thoroughly. After the ball milling was completed, a modified solution was obtained.

[0053] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 3.5%; the mass fraction of the urea solution is 4%.

[0054] The ball milling in this embodiment is sufficient at a ball milling speed of 1000 r / min for 1 hour.

[0055] Example 4. A method for removing heavy metals from circuit board wastewater according to this embodiment includes the following steps: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

[0056] In this embodiment, the physicochemical sedimentation sludge and the biochemical sludge are collected and filtered together, and the nickel-containing sludge is collected and filtered separately, and the mud cakes after filtration are transported out in a unified manner.

[0057] The biochemical system of this embodiment adopts a combination of anaerobic and aerobic treatment; The mixed liquor sludge concentration MLSS in the anoxic-aerobic tank was controlled to be 5.2 g / L, the temperature was 33°C, the dissolved oxygen concentration in the anoxic zone was controlled to be ≤0.5 mg / L, and the dissolved oxygen concentration in the aerobic zone was controlled to be 3.2 mg / L.

[0058] In the two-stage coagulation and sedimentation of this embodiment, 36 mg / L of modified montmorillonite agent can also be added.

[0059] The preparation method of the modified montmorillonite agent of this embodiment is: The montmorillonite is heat-treated at 152°C for 14 minutes, then cooled to 55°C at a rate of 2°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modifying liquid and stirred for modification treatment. After the stirring is completed, the modified montmorillonite agent is filtered and dried to obtain the modified montmorillonite agent.

[0060] The stirring speed of the stirring modification in this embodiment is 580 r / min, and the stirring time is 1 hour.

[0061] The preparation method of the modified liquid of this embodiment is: 4 parts of hydroxyapatite, 2 parts of zeolite powder, 7 parts of sodium dodecylbenzenesulfonate solution and 3 parts of urea solution were evenly mixed, and finally 2 parts of silane coupling agent KH550 were added. The mixture was ball-milled thoroughly and the ball-milling was completed to obtain a modified solution.

[0062] The mass fraction of the sodium dodecylbenzenesulfonate solution in this embodiment is 3%; the mass fraction of the urea solution is 4%.

[0063] The ball milling in this embodiment is sufficient at a ball milling speed of 1000 r / min for 1 hour.

[0064] Comparative Example 1. The difference from Example 3 is that no modified montmorillonite agent is added.

[0065] Comparative Example 2. The difference from Example 3 is that no modifying liquid is added in the preparation of the modified montmorillonite agent.

[0066] Comparative Example 3. The difference from Example 3 is that no hydroxyapatite or zeolite powder is added to the modified liquid.

[0067] Comparative Example 4. The difference from Example 3 is that no urea solution and silane coupling agent KH550 are added to the modified liquid.

[0068] The product performance tests of Examples 1-4 and Comparative Examples 1-4 are as follows:

[0069] It can be seen from Comparative Examples 1-4 and Example 3 that the product of Example 3 has excellent COD removal rate, heavy metal removal rate and ammonia nitrogen removal rate, and the performance coordination effect of the product is significant; The present invention does not add a modified montmorillonite agent, and the performance of the product has a significant deterioration trend. In the preparation of the modified montmorillonite agent, no modifying liquid is added, no hydroxyapatite and zeolite powder are added to the modifying liquid, and no urea solution and silane coupling agent KH550 are added to the modifying liquid. The performance of the product has a tendency to deteriorate. Only the modified montmorillonite agent obtained by the method of the present invention has the most significant performance effect of the product. Using other methods instead is not as obvious as the effect of the present invention.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0071] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for removing heavy metals from circuit board wastewater, characterized in that: The following steps are involved: Step 1: Pre-treat the wastewater; Cyanide wastewater is introduced into the cyanide wastewater regulating tank. The first step is CN Under alkaline conditions, it is oxidized to CNCl by NaClO. The second step is to use HClO to oxidize CNO Further oxidized to N and CO ; The nickel-containing wastewater is introduced into the nickel-containing wastewater regulating tank, and then pumped into the reaction sedimentation tank, where alkali, heavy capture agent, PAC and PAM are added to complete the removal of nickel; High-concentration organic wastewater is introduced into the corresponding collection pools, and then diluted into the comprehensive wastewater regulating pool for treatment; Step 2: The treated wastewater is then combined and subjected to two-stage coagulation and sedimentation, and the regeneration system is removed and improved.

2. The method for removing heavy metals from circuit board wastewater according to claim 1, characterized in that: The physicochemical sedimentation sludge and biochemical sludge are collected and filtered together. In addition, the nickel-containing sludge is collected and filtered separately. The mud cakes after filtration are transported out in a unified manner.

3. The method for removing heavy metals from circuit board wastewater according to claim 1, characterized in that: The biochemical system uses a combination of anaerobic and aerobic treatments for removal; The MLSS concentration of mixed liquor in the anoxic-aerobic tank is controlled to be 5-6 g / L, the temperature is 32-34°C, the dissolved oxygen concentration in the anoxic zone is controlled to be ≤0.5 mg / L, and the dissolved oxygen concentration in the aerobic zone is controlled to be 3-4 mg / L.

4. The method for removing heavy metals from circuit board wastewater according to claim 1, characterized in that: 35-40 mg / L of modified montmorillonite agent can also be added to the two-stage coagulation sedimentation.

5. A method for removing heavy metals from circuit board wastewater according to claim 4, characterized in that: The preparation method of modified montmorillonite agent is: The montmorillonite is heat-treated at 150-170°C for 10-15 minutes, then cooled to 55°C at a rate of 1-3°C / min and kept warm; the kept warm montmorillonite is added to a sufficient amount of modification liquid and stirred for modification treatment. After the stirring is completed, the mixture is filtered and dried to obtain a modified montmorillonite agent.

6. A method for removing heavy metals from circuit board wastewater according to claim 5, characterized in that: The stirring speed of the stirring modification is 550-750r / min, and the stirring time is 1h.

7. The method for removing heavy metals from circuit board wastewater according to claim 5, characterized in that: The preparation method of the modified liquid is: 2-5 parts of hydroxyapatite, 1-3 parts of zeolite powder, 5-8 parts of sodium dodecylbenzenesulfonate solution and 2-3 parts of urea solution are evenly mixed, and finally 2-3 parts of silane coupling agent KH550 are added. The mixture is ball-milled thoroughly and the ball-milling is completed to obtain a modified solution.

8. A method for removing heavy metals from circuit board wastewater according to claim 7, characterized in that: The mass fraction of the sodium dodecylbenzenesulfonate solution is 2-5%; the mass fraction of the urea solution is 3-5%.

9. The method for removing heavy metals from circuit board wastewater according to claim 7, characterized in that: The ball milling speed was 1000 r / min and the ball milling was carried out for 1 h.

Images