Printed circuit board copper, COD (Chemical Oxygen Demand) and ammonia nitrogen-containing wastewater treatment system capable of saving investment cost

Abstract

The invention relates to the technical field of printed circuit board wastewater treatment, and provides a printed circuit board copper, COD and ammonia nitrogen-containing wastewater treatment system capable of saving investment cost. Comprising an ammonia nitrogen electrolysis device, an acid-base acidification pretreatment tank, a comprehensive wastewater collection tank, a complex breaking reaction flocculation device, a first inclined tube sedimentation tank, an acid regulating tank, an aerobic tank, a second inclined tube sedimentation tank, a plate-and-frame filter press and a water outlet tank. The technical scheme provided by the invention has the beneficial effects that the ammonia nitrogen electrolysis device is additionally arranged, an anaerobic tank is omitted, the cost for constructing the anaerobic tank is reduced, the depth of the aerobic tank is not limited by the anaerobic tank, and the construction cost of a biochemical tank is greatly reduced; an aerobic tank is changed from a contact oxidation method to an activated sludge method, capital construction is simplified, management and control are simple, operation is convenient, the number of times of manual tank cleaning can be reduced, the labor amount of manual tank cleaning is reduced, and then the labor cost is reduced; the method not only effectively treats copper, COD and ammonia nitrogen in the wastewater, but also saves the investment cost of the wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board wastewater treatment, and in particular to an investment-saving printed circuit board wastewater treatment system containing copper, COD and ammonia nitrogen. Background Art

[0002] The types of wastewater generated in the multilayer printed circuit board (PCB) production process (excluding chemical nickel gold process) are divided into: (1) organic wastewater (COD), such as photoresist and developer; (2) EDTA complex copper wastewater, such as copper plating rinse water; (3) ammonia copper complex wastewater, such as etching rinse water; (4) general divalent copper rinse wastewater, such as electroplating copper and micro-etching rinse water; (5) acidic copper-containing wastewater, such as electroplating solution and degreasing.

[0003] Printed circuit board manufacturers use traditional wastewater treatment processes such as Figure 1 As shown in the figure, the main treatment methods are: (1) For the pollutant COD in the wastewater, anaerobic bacteria are used to cut the organic macromolecules into small organic molecules, and then aerobic bacteria oxidize the small organic molecules into carbon dioxide for emission; (2) For the pollutant ammonia nitrogen in the wastewater, aerobic bacteria are used to oxidize it into high-valent nitrogen such as nitrate nitrogen, and then anaerobic bacteria denitrify the high-valent nitrate nitrogen to nitrogen gas for emission; (3) For the pollutant EDTA-complexed copper in the wastewater, ferrous sulfate and hydrogen peroxide are added to carry out Fenton reaction. The generated hydroxyl radical (-OH) has strong oxidizing property, which can attack the coordination bond in the EDTA-Cu complex, thereby destroying the complex structure of EDTA and copper ions, allowing copper ions to be freed from the EDTA-complexed copper, and then the alkali and free divalent copper are strengthened to produce precipitated copper hydroxide, and finally flocculants are added to flocculate into sludge.

[0004] Disadvantages of traditional wastewater treatment systems: (1) High infrastructure investment costs: Traditionally, a biochemical treatment system is used, and the cost of the biochemical pool for PCB wastewater treatment generally accounts for more than three-quarters of the total infrastructure costs. The biochemical pool includes an anaerobic pool and an aerobic pool. In the entire infrastructure, in order to ensure the biochemical treatment effect, the anaerobic pool needs to have enough residence time for biochemical reactions, and the pool depth needs to be designed to be more than 5.5 meters, which means that the depth of the aerobic pool must also reach 5.5 meters to facilitate the flow of wastewater from the anaerobic pool to the aerobic pool. Under the current circumstances where the profit level of the PCB industry is not ideal, how to reduce the infrastructure costs of the wastewater treatment system, especially reducing the construction costs of the biochemical pool to reduce the PCB production costs, is a key link in saving wastewater treatment investment costs. (2) High operating costs for wastewater treatment: Traditionally, chemical reagents (such as iron salts, lime, etc.) are added to break up the complexes of heavy metal ions and form precipitates. At the same time, flocculants are added to help the precipitates clump together and accelerate sedimentation. The aerobic pool uses contact oxidation, and the biological filler pendants and the pool bottom must be cleaned manually every six months. This requires the PCB production to be shut down and the discharge of wastewater to be stopped. In addition, cleaning the sludge is also very difficult. The manual cleaning of the pool is labor-intensive and increases labor costs. Therefore, it not only affects production but also increases the operating costs of wastewater treatment. How to use simple methods to reduce the labor of manual cleaning of the pool and reduce the operating costs of wastewater treatment is another factor in saving investment costs for wastewater treatment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a printed circuit board wastewater treatment system containing copper, COD and ammonia nitrogen which saves investment costs.

[0006] The present invention is achieved as follows: a system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards, which saves investment costs, comprises:

[0007] Ammonia nitrogen electrolysis device, acid-base acidification pretreatment tank, comprehensive wastewater collection tank, complex breaking reaction flocculation device, first inclined tube sedimentation tank, acidity adjustment tank, aerobic tank, second inclined tube sedimentation tank, plate and frame filter press, and outlet tank;

[0008] The ammonia nitrogen wastewater flows to the ammonia nitrogen electrolysis device, which is used to convert the pollutant ammonia nitrogen in the ammonia nitrogen wastewater into nitrogen gas to obtain nitrogen-removed wastewater;

[0009] Copper wastewater and COD wastewater first flow into the acid-base acidification pretreatment tank, and after mixed pretreatment, the liquid located at the upper part of the acid-base acidification pretreatment tank flows into the comprehensive wastewater collection tank, and the nitrogen removal wastewater flows from the ammonia nitrogen electrolysis device into the comprehensive wastewater collection tank, and after mixing, primary wastewater is obtained;

[0010] The primary wastewater flows from the comprehensive wastewater collection tank to the complex breaking reaction flocculation device, which is used to destroy the complex structure of EDTA-complexed copper, a pollutant in the primary wastewater, through hydroxyl radicals generated by the Fenton reaction, thereby releasing copper ions. A strong base is then added, and the strong base reacts with the copper ions to produce precipitated copper hydroxide. Finally, a flocculant is added to flocculate the copper hydroxide into sludge to obtain secondary wastewater.

[0011] The secondary wastewater flows from the flocculation device to the first inclined tube sedimentation tank, where solid-liquid separation is performed on the secondary wastewater. The sludge solids located in the lower part of the first inclined tube sedimentation tank are sucked into the plate and frame filter press through a first discharge pipe. The plate and frame filter press produces sludge cakes. The liquid located in the upper part of the first inclined tube sedimentation tank flows into the acidity adjustment tank to obtain tertiary wastewater.

[0012] The tertiary wastewater flows from the acid regulating tank to the aerobic tank, and the aerobic tank is used to decompose the pollutant COD in the tertiary wastewater into carbon dioxide through microbial bacteria to obtain quaternary wastewater;

[0013] The aerobic tank is equipped with an oxygen supply, a flow pusher and a sludge extractor. The oxygen supply includes a fan, an air supply pipe and an aeration nozzle. The aeration nozzle is distributed at the bottom of the aerobic tank. The aeration nozzle is connected to the outlet of the fan through the air supply pipe. The inlet of the fan is exposed to the outside air. The flow pusher is arranged at the water outlet of the aerobic tank and is used to push the sludge carried away by the water flow back to the water inlet of the aerobic tank. The suction pipe of the sludge extractor is arranged at the bottom of the second inclined tube sedimentation tank, and the discharge pipe of the sludge extractor is arranged at the water inlet of the aerobic tank.

[0014] The quaternary wastewater flows from the aerobic tank to the second inclined tube sedimentation tank, where solid-liquid separation is performed on the quaternary wastewater. The sludge solids located at the lower part of the second inclined tube sedimentation tank are sucked into the plate and frame filter press through a second discharge pipe. The plate and frame filter press produces sludge blocks, and the liquid located at the upper part of the second inclined tube sedimentation tank flows to the outlet tank.

[0015] Furthermore, it also includes a fungus delivery device, which is installed above the aerobic pool. The fungus delivery device includes a bacteria storage tank, which is used to store the microorganisms.

[0016] Furthermore, the depth of the aerobic pool is changed from 5.5 meters to 3.5 meters.

[0017] Furthermore, the mixed pretreatment specifically involves mixing the copper wastewater and the COD wastewater and adjusting the pH value to within the range of 2 to 3 for reaction.

[0018] Furthermore, in the decomposition reaction flocculation device, ferrous sulfate and hydrogen peroxide are added to carry out the Fenton reaction.

[0019] Furthermore, in the decomplexation reaction flocculation device, the strong base is sodium hydroxide, and the sodium hydroxide and the copper ions produce precipitated copper hydroxide. Secondly, the pollutant factors EDTA-complexed copper and copper ions that are not completely decomplexed are subjected to secondary decomplexation precipitation by the added sodium sulfide again to produce precipitated copper sulfide. Finally, a flocculant is added to flocculate the copper hydroxide and copper sulfide into sludge to obtain secondary wastewater.

[0020] Furthermore, in the decomposition reaction flocculation device, the flocculants are polyaluminum chloride and polyacrylamide.

[0021] Furthermore, the acid adjustment tank is used to add sulfuric acid to adjust the pH value of the tertiary wastewater to within the range of eight to nine.

[0022] Compared with the background technology, the technical solution of the present invention has the following advantages:

[0023] The addition of an ammonia nitrogen electrolysis device and the elimination of an anaerobic tank reduce the cost of building an anaerobic tank. The depth of the aerobic tank is not limited by the anaerobic tank, thereby significantly reducing the construction cost of the biochemical tank. The aerobic tank uses an activated sludge method instead of a contact oxidation method, which simplifies infrastructure construction, is simple to control, and is easy to operate. It can reduce the number of manual pool cleanings, reduce the labor workload, and thus reduce labor costs. The aerobic tank is used in conjunction with a fan and a flow pusher, and is fed with microbial bacteria for COD degradation. The bacterial flora is stable, which helps to treat the pollutant COD. The present invention not only effectively treats copper, COD, and ammonia nitrogen in wastewater, but also saves wastewater investment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 It is a schematic diagram of a traditional wastewater treatment process in the background technology.

[0026] Figure 2 It is a schematic diagram of the process flow corresponding to the wastewater treatment system of the present invention.

[0027] Figure 3 It is a structural schematic diagram of the wastewater treatment system of the present invention.

[0028] Figure 4 It is a connection diagram of the aerobic tank, oxygen supply device, flow pusher and sludge extractor in the present invention.

[0029] Figure 5It is a schematic diagram of the positions of the fungus delivery device and the aerobic pool in the present invention.

[0030] Figure numerals: ammonia nitrogen electrolysis device 1; acid-base acidification pretreatment tank 11; comprehensive wastewater collection tank 2; complex breaking reaction flocculation device 3; first inclined tube sedimentation tank 4; acidity adjustment tank 5; aerobic tank 6; oxygen supply device 61; fan 611; air supply pipe 612; aeration nozzle 613; flow pusher 62; sludge extractor 63; suction pipe 631; discharge pipe 632; second inclined tube sedimentation tank 7; plate and frame filter press 8; water outlet tank 9; fungus delivery device 10; bacteria storage tank 101; bracket 102; drive motor 103. DETAILED DESCRIPTION

[0031] The embodiment of the present invention provides a system for treating wastewater containing copper, COD, and ammonia nitrogen from printed circuit boards, which saves investment costs. The overall concept of the technical solution is as follows:

[0032] 1. Adding an ammonia nitrogen electrolysis unit to convert ammonia nitrogen, a pollutant in ammonia nitrogen wastewater, into nitrogen gas. The cost of a biochemical tank for PCB wastewater treatment generally accounts for more than three-quarters of the total construction cost. The biochemical tank includes both anaerobic and aerobic tanks. Eliminating the anaerobic tank significantly reduces the cost of the biochemical tank. The anaerobic and denitrification processes are eliminated from the wastewater treatment process, while the ammonia nitrogen electrolysis pretreatment process is added, simplifying the process flow. The construction cost of the ammonia nitrogen electrolysis unit is much lower than that of the anaerobic tank.

[0033] 2. The depth of the aerobic tank is not limited by the anaerobic tank, which reduces the construction depth of the aerobic tank and further reduces the construction cost of the aerobic tank.

[0034] 3. The aerobic tank uses the activated sludge process instead of the contact oxidation process. By eliminating the use of biological filler pendants, the labor required for manual cleaning of the aerobic tank is reduced. The flow propeller acts in the opposite direction of the water flow, pushing the sludge from the bottom of the aerobic tank back to the front of the tank. A sludge pump is then used to pump some of the sludge that has been lost to the second inclined tube sedimentation tank back into the aerobic tank, reducing the loss of microbial bacteria. The absence of biological filler pendants reduces the frequency of manual cleaning, reduces the labor involved, and reduces labor costs, thereby lowering the operational and maintenance costs of wastewater treatment. When the sludge content in the aerobic tank exceeds 30%, sludge pumping from the second inclined tube sedimentation tank is stopped, reducing the total sludge content in the aerobic tank. If the aerobic tank is unavailable for maintenance due to mechanical failure or bacterial imbalance, a mobile submersible pump can be used to manually clean the tank and remove the sludge from the aerobic tank. The absence of biological filler pendants makes operation easy.

[0035] 4. Abandon the hyperoxia bacteria group and choose to add appropriate aerobic bacteria group (aerobic denitrification COD degradation bacteria) to improve biochemical efficiency, cancel the biological filler pendants, and cancel the anaerobic tank, so there is no need to manually clean the anaerobic tank, reduce labor costs, and further reduce the operation and maintenance costs of wastewater treatment.

[0036] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] See Figures 1 to 5 , a preferred embodiment of the present invention.

[0038] A system for treating wastewater containing copper, COD, and ammonia nitrogen from printed circuit boards that saves investment costs comprises:

[0039] Ammonia nitrogen electrolysis device 1, acid-base acidification pretreatment tank 11, comprehensive wastewater collection tank 2, complex breaking reaction flocculation device 3, first inclined tube sedimentation tank 4, acidity adjustment tank 5, aerobic tank 6, second inclined tube sedimentation tank 7, plate and frame filter press 8 and outlet tank 9;

[0040] The ammonia nitrogen wastewater flows to the ammonia nitrogen electrolysis device 1, which is used to convert the pollutant ammonia nitrogen in the ammonia nitrogen wastewater into nitrogen gas to obtain nitrogen-removed wastewater;

[0041] Copper wastewater and COD wastewater first flow into the acid-base acidification pretreatment tank 11. After mixed pretreatment, the liquid at the upper part of the acid-base acidification pretreatment tank 11 flows into the comprehensive wastewater collection tank 2. The denitrification wastewater flows from the ammonia nitrogen electrolysis device 1 into the comprehensive wastewater collection tank 2. After mixing, primary wastewater is obtained.

[0042] The primary wastewater flows from the comprehensive wastewater collection tank 2 to the complex breaking reaction flocculation device 3, which is used to destroy the complex structure of EDTA-complexed copper, a pollutant in the primary wastewater, through hydroxyl radicals generated by the Fenton reaction, thereby releasing copper ions. A strong base is then added, and the strong base reacts with the copper ions to produce precipitated copper hydroxide. Finally, a flocculant is added to flocculate the copper hydroxide into sludge to obtain secondary wastewater.

[0043] The secondary wastewater flows from the decomposition reaction flocculation device 3 to the first inclined tube sedimentation tank 4, where solid-liquid separation is performed on the secondary wastewater. The sludge solids located in the lower part of the first inclined tube sedimentation tank 4 are sucked into the plate and frame filter press 8 through a first discharge pipe. The plate and frame filter press 8 produces sludge cakes, and the liquid located in the upper part of the first inclined tube sedimentation tank 4 flows into the acidity adjustment tank 5 to obtain tertiary wastewater.

[0044] The tertiary wastewater flows from the acid regulating tank 5 to the aerobic tank 6, and the aerobic tank 6 is used to decompose the pollutant COD in the tertiary wastewater into carbon dioxide through microbial bacteria to obtain quaternary wastewater;

[0045] The aerobic tank 6 is equipped with an oxygen supply 61, a flow pusher 62 and a sludge extractor 63. The oxygen supply 61 includes a fan 611, an air supply pipe 612 and an aeration nozzle 613. The aeration nozzle 613 is distributed at the bottom of the aerobic tank 6. The aeration nozzle 613 is connected to the outlet of the fan 611 through the air supply pipe 612. The inlet of the fan 611 is exposed to the outside air. The flow pusher 62 is arranged at the water outlet of the aerobic tank 6 to push the sludge carried away by the water flow back to the water inlet direction of the aerobic tank 6. The suction pipe 631 of the sludge extractor 63 is arranged at the bottom of the second inclined tube sedimentation tank 7, and the discharge pipe 632 of the sludge extractor 63 is arranged at the water inlet of the aerobic tank 6.

[0046] The quaternary wastewater flows from the aerobic tank 6 to the second inclined tube sedimentation tank 7, and the quaternary wastewater undergoes solid-liquid separation in the second inclined tube sedimentation tank 7. The sludge solids located at the lower part of the second inclined tube sedimentation tank 7 are sucked into the plate and frame filter press 8 through the second discharge pipe. The plate and frame filter press 8 produces sludge blocks, and the liquid located at the upper part of the second inclined tube sedimentation tank 7 flows to the outlet tank 9.

[0047] The beneficial effects or advantages of the technical solution of the present invention are as follows: an ammonia nitrogen electrolysis device 1 is added, the anaerobic tank is eliminated, the cost of building the anaerobic tank is reduced, the depth of the aerobic tank 6 is not limited by the anaerobic tank, and the construction cost of the biochemical tank is greatly reduced; the aerobic tank 6 uses an activated sludge method instead of a contact oxidation method, which simplifies infrastructure construction, is simple to control, and is easy to operate, which can reduce the number of manual tank cleanings, reduce the labor workload of manual tank cleaning, and thus reduce labor costs; the aerobic tank 6 is used in conjunction with a fan and a flow pusher, and is then fed with microbial bacteria for COD degradation, so the bacterial population is stable, which helps to treat the pollutant COD; the present invention not only effectively treats copper, COD, and ammonia nitrogen in wastewater, but also saves wastewater investment costs.

[0048] Aerobic pools require a certain amount of sludge for bacterial colonization. This sludge is primarily introduced from previous processes or supplied manually, allowing microorganisms to colonize the pool bottom sludge and reduce bacterial loss. As microorganisms decompose organic matter, they also continuously grow and reproduce. Some organic matter (COD) is used to synthesize new microbial cell material, while another portion is oxidized and decomposed into products such as carbon dioxide, providing energy for the microbial life cycle. Microbial metabolism produces a small amount of sludge.

[0049] The flow pusher 62 can be a propeller device driven by a motor, and the sludge retractor 63 can be a suction pump. The flow pusher 62 is used to push the sludge carried away by the water flow from the bottom of the aerobic tank 6 back to the front end of the aerobic tank, reducing sludge loss and thus stabilizing the bacterial population. The sludge carried to the second inclined tube sedimentation tank by the water flow can be partially withdrawn to the water inlet of the aerobic tank 6 by the sludge retractor 63 after a preset period of time.

[0050] Furthermore, a fungus delivery device 10 is included. The fungus delivery device 10 is installed above the aerobic pool 6. The fungus delivery device 10 includes a bacteria storage tank 101. The bacteria storage tank 101 is used to store the microorganisms.

[0051] The beneficial effects of this technical solution are: according to the total amount of wastewater treated every day and the COD value of the effluent pool, appropriate trace amounts are added through the fungus delivery device.

[0052] In this embodiment, the mushroom delivery device 10 includes a bracket 102, a drive motor 103, an MCU and an operation panel. The bacteria storage tank 101 is installed on the bracket 102, and the MCU is electrically connected to the operation panel. The driving circuit is manually activated through the operation panel to change the delivery angle of the bacteria storage tank.

[0053] The microbial bacteria are aerobic denitrifying COD-degrading bacteria in the prior art.

[0054] Furthermore, the depth of the aerobic pool 6 is changed from 5.5 meters to 3.5 meters.

[0055] Anaerobic tanks must be at a certain depth (generally at least 5.5 meters). Otherwise, the wastewater remains in the tank for too short a time, failing to achieve the desired treatment effect. Each additional unit of tank depth increases the water pressure at the bottom, necessitating an increase in tank wall thickness, which exponentially increases the construction cost of the biochemical treatment tank. Therefore, by eliminating the anaerobic tank, the aerobic tank 6 does not necessarily need to be 5.5 meters deep. The present invention provides a 3.5-meter depth, further reducing the cost of constructing the aerobic tank 6.

[0056] Furthermore, the mixed pretreatment specifically involves mixing the copper wastewater and the COD wastewater and adjusting the pH value to within the range of 2 to 3 for reaction.

[0057] Acid-base acidification: The organic waste alkali is referred to as alkaline water, and the copper-containing electroplating wastewater is referred to as acid water. After the acid water and alkaline water are mixed and the pH value is adjusted to the range of 2 to 3 for reaction, the supernatant in the acid-base acidification pretreatment tank is discharged to the comprehensive wastewater collection tank, and the waste residue in the acid-base acidification pretreatment tank is salvaged and bagged.

[0058] Furthermore, in the decomposition reaction flocculation device 3, ferrous sulfate and hydrogen peroxide are added to carry out the Fenton reaction.

[0059] Furthermore, in the decomplexation reaction flocculation device 3, the strong base is sodium hydroxide, and the sodium hydroxide and the copper ions produce precipitated copper hydroxide. Secondly, the pollutant factors EDTA-complexed copper and copper ions that are not completely decomplexed are subjected to secondary decomplexation precipitation by the added sodium sulfide again to produce precipitated copper sulfide. Finally, a flocculant is added to flocculate the copper hydroxide and copper sulfide into sludge to obtain secondary wastewater.

[0060] Furthermore, in the decomposition reaction flocculation device 3, the flocculants are polyaluminum chloride and polyacrylamide.

[0061] Furthermore, the acid adjustment tank 5 is used to add sulfuric acid to adjust the pH value of the tertiary wastewater to be within the range of eight to nine.

[0062] Since strong alkali is added in the decomposition reaction flocculation device 3 to precipitate copper hydroxide, the pH value of the wastewater is alkaline. Sulfuric acid is added in the acid adjustment tank 5 to adjust the pH value of the wastewater, which is conducive to the survival of microorganisms and bacteria.

[0063] The working principle of the wastewater treatment system of the present invention:

[0064] 1. Simplify the wastewater treatment process

[0065] In the process flow of traditional wastewater treatment scheme, the anaerobic and denitrification processes were deleted, and the ammonia nitrogen electrolysis pre-treatment process was added.

[0066] The function of the ammonia nitrogen electrolysis device is to treat ammonia nitrogen directly by electrolyzing it into nitrogen gas. This eliminates the complex process of oxidizing it into nitrate nitrogen in the anaerobic tank and then returning it to the anaerobic tank to reduce it into nitrogen gas.

[0067] Principle of ammonia nitrogen electrolysis treatment:

[0068] Direct oxidation: On the anode surface, ammonia nitrogen directly loses electrons under the action of the electric field to undergo oxidation reaction. 4+ First, it is converted into ammonia hydrate NH3·H2O, and then oxidized into harmless substances such as nitrogen N2 at the anode, thereby achieving the removal of ammonia nitrogen. The reaction formula can be expressed as: 2NH4 + -6e - +6OH - →N2+6H2O.

[0069] Indirect oxidation: When chloride ions Cl exist in wastewater - When the anode is chlorinated, chloride ions discharge to produce chlorine gas Cl2. Chlorine gas reacts with water to produce hypochlorous acid HClO and other strong oxidizing substances. These substances can oxidize ammonia nitrogen into nitrogen gas, thereby achieving the removal of ammonia nitrogen. The reaction formula is as follows:

[0070] Anode: 2Cl - -2e - →Cl2

[0071] In solution: Cl2+H2O→HClO+H + +CI -

[0072] Oxidation reaction: 2NH4 + +3HClO→N2+3H2O+5H + +3Cl -

[0073] The use of ammonia nitrogen electrolysis method abandons the anaerobic process, reduces the cost of building anaerobic pools, and thus greatly reduces the construction cost of biochemical pools.

[0074] 2. Reduce the construction depth of the aerobic pool

[0075] Working principle of aerobic pool (metabolism of microorganisms): Aerobic bacteria use organic matter in organic wastewater as carbon source and energy to grow and reproduce under aerobic conditions. Aerobic bacteria decompose organic pollutants into simple inorganic substances such as carbon dioxide and water. For example, for glucose (C6H 12 O6) decomposition. Its reaction formula is:

[0076]

[0077] As microorganisms decompose organic matter, they also continue to grow and reproduce. Some of the organic matter is used to synthesize new microbial cell substances, while the rest is oxidized and decomposed into products such as carbon dioxide, providing energy for the life activities of microorganisms.

[0078] Reducing the depth of the aerobic tank further reduces construction costs: Anaerobic tanks must be at a certain depth (generally at least 5.5 meters). Otherwise, the treated water will remain in the anaerobic tank for too short a time, failing to achieve the desired treatment effect. Each additional unit of tank depth increases the water pressure at the bottom of the tank, which necessitates increasing the thickness of the red wall, thus exponentially increasing the construction cost of the biochemical treatment tank. Therefore, by eliminating the anaerobic tank, the aerobic tank does not need to be 5.5 meters deep; we designed it to be 3.5 meters deep, further reducing the cost of building the aerobic tank.

[0079] 3. Use activated sludge method to replace contact oxidation method (cancel the use of biological filler)

[0080] Disadvantages of biochemical treatment using the contact oxidation method: PCB manufacturers’ biochemical aerobic pools originally generally used the contact oxidation method. However, the contact oxidation method has a fatal problem, which is that it is extremely difficult to maintain. The manual pool cleaning every six months not only requires the suspension of PCB production, but also makes sludge cleaning very difficult. After one year of use, the COD removal efficiency of the aerobic pool organisms drops rapidly.

[0081] This invention changes the biochemical reaction from a contact oxidation process to an activated sludge process, eliminating the need for biological filler pendants. The aerobic pool uses a flow propeller to push back and a fan to provide oxygen, reducing the number of pool cleanings and achieving excellent cleaning results. This reduces the labor and labor costs associated with manual pool cleaning. This measure reduces production downtime, improves biochemical effectiveness and efficiency, and reduces wastewater treatment operating costs.

[0082] This invention changes the biochemical reaction from a contact oxidation process to an activated sludge process, eliminating the need for biological pendant fillers and directly using a flow propeller to push back and a fan to provide oxygen. This method shortens the pool cleaning time and does not affect production. This measure eliminates production downtime caused by biochemical pool maintenance, improves biochemical effectiveness and efficiency, and reduces wastewater treatment operating costs.

[0083] 4. Choose to add appropriate aerobic bacteria

[0084] PCB manufacturers previously used a combination of anaerobic and aerobic bacterial communities for biochemical treatment of wastewater. This invention eliminates the need for anaerobic bacteria and biofillers and instead incorporates aerobic denitrifying COD-degrading bacteria in trace amounts, improving the stability of the aerobic community and further reducing operational and maintenance costs for wastewater treatment.

[0085] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards that saves investment costs, characterized in that: include: Ammonia nitrogen electrolysis device, acid-base acidification pretreatment tank, comprehensive wastewater collection tank, complex breaking reaction flocculation device, first inclined tube sedimentation tank, acidity adjustment tank, aerobic tank, second inclined tube sedimentation tank, plate and frame filter press, and outlet tank; The ammonia nitrogen wastewater flows to the ammonia nitrogen electrolysis device, which is used to convert the pollutant ammonia nitrogen in the ammonia nitrogen wastewater into nitrogen gas to obtain nitrogen-removed wastewater; Copper wastewater and COD wastewater first flow into the acid-base acidification pretreatment tank, and after mixed pretreatment, the liquid located at the upper part of the acid-base acidification pretreatment tank flows into the comprehensive wastewater collection tank, and the nitrogen removal wastewater flows from the ammonia nitrogen electrolysis device into the comprehensive wastewater collection tank, and after mixing, primary wastewater is obtained; The primary wastewater flows from the comprehensive wastewater collection tank to the complex breaking reaction flocculation device, which is used to destroy the complex structure of EDTA-complexed copper, a pollutant in the primary wastewater, through hydroxyl radicals generated by the Fenton reaction, thereby releasing copper ions. A strong base is then added, and the strong base reacts with the copper ions to produce precipitated copper hydroxide. Finally, a flocculant is added to flocculate the copper hydroxide into sludge to obtain secondary wastewater. The secondary wastewater flows from the flocculation device to the first inclined tube sedimentation tank, where solid-liquid separation is performed on the secondary wastewater. The sludge solids located in the lower part of the first inclined tube sedimentation tank are sucked into the plate and frame filter press through a first discharge pipe. The plate and frame filter press produces sludge cakes. The liquid located in the upper part of the first inclined tube sedimentation tank flows into the acidity adjustment tank to obtain tertiary wastewater. The tertiary wastewater flows from the acid regulating tank to the aerobic tank, and the aerobic tank is used to decompose the pollutant COD in the tertiary wastewater into carbon dioxide through microbial bacteria to obtain quaternary wastewater; The aerobic tank is equipped with an oxygen supply, a flow pusher and a sludge extractor. The oxygen supply includes a fan, an air supply pipe and an aeration nozzle. The aeration nozzle is distributed at the bottom of the aerobic tank. The aeration nozzle is connected to the outlet of the fan through the air supply pipe. The inlet of the fan is exposed to the outside air. The flow pusher is arranged at the water outlet of the aerobic tank and is used to push the sludge carried away by the water flow back to the water inlet of the aerobic tank. The suction pipe of the sludge extractor is arranged at the bottom of the second inclined tube sedimentation tank, and the discharge pipe of the sludge extractor is arranged at the water inlet of the aerobic tank. The quaternary wastewater flows from the aerobic tank to the second inclined tube sedimentation tank, where solid-liquid separation is performed on the quaternary wastewater. The sludge solids located at the lower part of the second inclined tube sedimentation tank are sucked into the plate and frame filter press through a second discharge pipe. The plate and frame filter press produces sludge blocks, and the liquid located at the upper part of the second inclined tube sedimentation tank flows to the outlet tank.

2. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: It also includes a fungus delivery device, which is installed above the aerobic pool. The fungus delivery device includes a bacteria storage tank, which is used to store the microorganisms.

3. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: The depth of the aerobic pool was changed from 5.5 meters to 3.5 meters.

4. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: The mixed pretreatment specifically involves mixing the copper wastewater and the COD wastewater and adjusting the pH value to within a range of 2 to 3 for reaction.

5. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: In the decomposition reaction flocculation device, ferrous sulfate and hydrogen peroxide are added to carry out the Fenton reaction.

6. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: In the decomplexation reaction flocculation device, the strong base is sodium hydroxide, and the sodium hydroxide and the copper ions produce precipitated copper hydroxide. Secondly, the incompletely decomplexed pollutant EDTA-complexed copper and copper ions are subjected to secondary decomplexation precipitation by the added sodium sulfide again to produce precipitated copper sulfide. Finally, a flocculant is added to flocculate the copper hydroxide and copper sulfide into sludge to obtain secondary wastewater.

7. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: In the decomposition reaction flocculation device, the flocculants are polyaluminum chloride and polyacrylamide.

8. The system for treating wastewater containing copper, COD and ammonia nitrogen from printed circuit boards according to claim 1, which saves investment costs, is characterized in that: The acid adjustment tank is used to add sulfuric acid to adjust the pH value of the tertiary wastewater to within the range of eight to nine.

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