A treatment process for printed circuit board production wastewater

Abstract

The application relates to the technical field of wastewater treatment, and particularly discloses a treatment process for printed circuit board (PCB) production wastewater. The treatment process comprises the following steps: 1) classifying and collecting the wastewater, breaking the network and adjusting the water quality and quantity; 2) adding lime, ferrous sulfate, polyaluminum chloride and polyacrylamide, and then carrying out solid-liquid separation after stirring and reaction, and discharging the water in the upper layer; 3) adding sodium sulfide, ferrous sulfate, polyaluminum chloride and polyacrylamide, and then carrying out solid-liquid separation after stirring and reaction, and discharging the water in the upper layer; 4) removing fine heavy metal flocculation through a filtering unit, and adjusting the pH; 5) injecting the wastewater into an anoxic biochemical tank for anoxic denitrification treatment, and discharging the water; 6) injecting the wastewater into an aeration biochemical tank for aerobic aeration nitrification treatment, and discharging the water; and 7) injecting the wastewater into a sedimentation tank, adding polyaluminum chloride and polyacrylamide, carrying out solid-liquid separation after stirring and reaction, discharging the water in the upper layer, and obtaining clean water. The application has the advantages that the removal effect of pollutants in the PCB wastewater is further improved, and the water quality of the discharged water is improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and in particular to a treatment process for wastewater from printed circuit board manufacturing. Background Technology

[0002] During the production of printed circuit boards (PCBs), processes such as grinding, washing, and developing generate a large amount of combined wastewater. This wastewater contains suspended solids, heavy metals such as copper ions, and various pollutants such as COD and ammonia nitrogen. Ionic and complexed heavy metals coexist, the pH is acidic (3-5), and the water quality and quantity fluctuate greatly.

[0003] Existing integrated wastewater treatment processes are mostly simple series processes of "primary chemical precipitation + biological treatment". This treatment process has a relatively limited ability to remove pollutants. When the pollutant content in the wastewater is high, the effluent quality is difficult to meet the standards and needs. Therefore, there is still room for improvement. Summary of the Invention

[0004] In order to further improve the removal of pollutants from PCB wastewater and thus improve the quality of effluent, this application provides a treatment process for wastewater from printed circuit board manufacturing.

[0005] The treatment process for wastewater from printed circuit board manufacturing provided in this application adopts the following technical solution: A process for treating wastewater from printed circuit board manufacturing includes the following steps: Step 1) Collect wastewater by category, break down the chelates, and adjust the water quality and quantity to obtain balanced wastewater; Step 2) Add lime, ferrous sulfate, polyaluminum chloride and polyacrylamide to the equalized wastewater, stir and react, then separate the solid and liquid, and the upper effluent is the first-level chemically treated water. Step 3) Add sodium sulfide, ferrous sulfate, polyaluminum chloride and polyacrylamide to the primary chemically treated water. After stirring and reacting, the solid and liquid are separated, and the upper effluent is the secondary chemically treated water. Step 4) After the secondary chemically treated water is filtered to remove fine heavy metal flocs, the pH is adjusted to 7.0-8.0 to obtain pretreated water; Step 5) Inject the pretreated water into the anoxic biological tank for anoxic denitrification treatment, and the effluent is the primary biological treated water. Step 6) The primary biologically treated water is injected into the aerated biological treatment tank for aerobic aeration nitrification treatment. The effluent is then used to obtain secondary biologically treated water. A portion of the effluent from the aerated biological treatment tank is returned to the anoxic biological treatment tank, with a return ratio of 100%-200%. Step 7) Inject the secondary biological treated water into the sedimentation tank, add polyaluminum chloride and polyacrylamide, stir and react, then separate the solid and liquid, and the upper effluent is the purified water. The anoxic biochemical tank is filled with anoxic biological suspension packing material, which is enriched with Hansenula saturnii, Tauella taurinae, and Thiobacillus denitrificationus. The aerated biochemical tank is filled with aerobic biological suspended packing material, which is enriched with Sphingosine monocytogenes, Bacillus subtilis, Nitrosomonas nitrosamines, and Nitrosobacterium vesiculosum.

[0006] By adopting the above technical solution, the PCB wastewater is first classified and broken down to eliminate the chelating effect of complexing agents such as EDTA and citric acid on heavy metals. Then, a two-stage chemical precipitation-filtration process is used to remove heavy metals, reducing the toxicity and inhibition of heavy metals on subsequent biological bacteria. The anoxic-aerobic biochemical combination process is then used, where the anoxic tank's composite functional bacteria achieve efficient denitrification and nitrogen removal, while the aerobic tank completes ammonia nitrification and organic matter degradation. The nitrified liquid is refluxed back to the anoxic tank for further removal of nitrate nitrogen. The entire process works synergistically to simultaneously remove heavy metals, COD, ammonia nitrogen, and total nitrogen, effectively improving the treatment instability caused by fluctuations in the quality and quantity of PCB wastewater and improving the effluent quality.

[0007] By combining Hansenula saturnii, Tauella tauren, and Thiobacillus denitrification, the denitrification effect is significantly improved and the effluent quality is better through the synergistic effect of each bacterium.

[0008] By combining Sphingomonas vesicatoria, Bacillus subtilis, Nitrosomonas nitrosamines, and Nitrosobacterium vesicatoria, the synergistic effect of each bacterium in degrading organic matter is improved, thus enhancing the quality of effluent.

[0009] Preferably, in step 5), the filling rate of the anoxic biological suspension packing is 33-37%.

[0010] By adopting the above technical solution and by specifically selecting the filling rate of the anoxic biological suspension packing, the collision and friction between the packings are moderate. This can provide sufficient biological attachment carriers to ensure the carrying capacity of functional microorganisms, while avoiding the obstruction of stirring in the tank and the dead corners of packing accumulation caused by excessive packing, thus ensuring the efficient progress of the anoxic denitrification reaction.

[0011] Preferably, in step 5, the inoculation and acclimatization process for the microbial strains in the anoxic biological suspension packing is as follows: Polypropylene MBBR suspension packing is filled into an anoxic biological tank. Then, Saturnian yeast solution, Tauella bacteria solution, and Thiobacillus denitrification bacteria solution are mixed and added to the anoxic biological tank at a volume ratio of 1.9-2.1:2.9-3.1:0.9-1.1. The mixture is acclimated until a uniform yellowish-brown slippery biofilm forms on the surface of the packing, thus completing the biofilm formation on the packing.

[0012] By adopting the above technical solution and specifically selecting the ratio of Saturnian Hansenula polymorpha culture, Tauerella polymorpha culture, and Thiobacillus denitrification culture, it is beneficial for Saturnian Hansenula polymorpha, Tauerella polymorpha, and Thiobacillus denitrification to co-colonize and accumulate on the packing material, construct a stable anoxic composite functional biofilm, further enhance the system's denitrification and sulfur autotrophic denitrification capabilities, and reduce the risk of acclimatization failure.

[0013] Preferably, the OD of the Saturn Hansenula polymorpha culture is... 600 =1.0-1.2, the OD of the *Taurizoctonia solani* bacterial culture 600 =0.8-1, the OD of the *Thiobacillus denitrification* bacterial solution 600 =0.6-0.8.

[0014] By adopting the above technical solution and specifically selecting the OD of each bacterium 600 The inoculation solution has sufficient bacterial concentration and biological activity to ensure the initial bacterial population after inoculation, which is conducive to the rapid attachment and biofilm formation of functional bacteria and shortens the acclimatization period.

[0015] Preferably, in step 5), the dissolved oxygen in the pool is controlled online to be ≤0.5mg / L.

[0016] By adopting the above technical solution and controlling dissolved oxygen ≤0.5mg / L, the competitive inhibition of molecular oxygen on the denitrification process can be reduced, providing a suitable hypoxic metabolic environment for Taurella and Thiobacillus denitrification, and ensuring the smooth progress of the denitrification reaction.

[0017] Preferably, in step 6), the filling rate of the aerobic biological suspension packing is 28-32%.

[0018] By adopting the above technical solution and specifically selecting the filling rate of the aerobic biological suspension packing, it is possible to better adapt to the aerobic aeration aeration process. The packing can be fully tumbled with the aeration, providing sufficient attachment sites for nitrifying bacteria and heterotrophic functional bacteria, while not hindering aeration mass transfer and ensuring the efficiency of nitrification reaction.

[0019] Preferably, in step 6, the inoculation and acclimatization of the microbial strains for the aerobic biological suspension packing is specifically as follows: Polypropylene MBBR suspension packing is filled into the aeration biological treatment tank. Then, sphingomonas velutipes bacterial solution, Bacillus subtilis bacterial solution, Nitrosomonas nitrosamine bacterial solution, and Nitrosobacterium velutipes bacterial solution are mixed and added to the aeration biological treatment tank at a volume ratio of 0.9-1.1:0.9-1.1:1.9-2.1:1.9-2.1. The mixture is acclimated until a uniform yellowish-brown slippery biofilm forms on the surface of the packing, thus completing the biofilm formation on the packing.

[0020] By adopting the above technical solution and specifically selecting the ratio of Sphingomonas vesicatoria, Bacillus subtilis, Nitrosomonas nitrifying bacteria, and Nitrosobacterium vesicatoria, it is more conducive to the synergistic growth of autotrophic nitrifying bacteria and heterotrophic functional bacteria, forming a stable aerobic biofilm on the packing surface, enhancing the ability of ammonia nitrogen nitrification and residual organic matter degradation, and improving the system's resistance to shock loads.

[0021] Preferably, the OD of the *Sphingosine monocytogenes* bacterial suspension is... 600 =0.8-1.0, the OD of the Bacillus subtilis bacterial solution 600 =1.0-1.2, the OD of the Nitrosomonas bacterial culture 600 =0.4-0.6, the OD of the *Nitrobacterium vesiculosus* bacterial solution 600 =0.4-0.6.

[0022] By adopting the above technical solution and specifically selecting the OD of each bacterium 600 The range is designed to better match the inherent growth characteristics of different bacterial species. The concentration of autotrophic nitrifying bacteria is relatively low. This OD range ensures inoculation activity, which is conducive to the colonization and enrichment of nitrifying bacteria and avoids slow nitrification function due to insufficient inoculation activity.

[0023] Preferably, in step 6), the dissolved oxygen in the aeration system is controlled at 2.0-3.5 mg / L, and the system operating water temperature is maintained at 18-35℃.

[0024] By adopting the above technical solution, and by specifically selecting dissolved oxygen of 2.0-3.5 mg / L, this dissolved oxygen range meets the aerobic metabolic needs of nitrifying and nitrifying bacteria; by specifically selecting water temperature to be maintained at 18-35℃, this temperature range covers the survival and metabolic window of various functional bacterial groups in the aerobic tank. The activity of nitrifying bacteria will not decrease significantly due to excessively low temperature, nor will enzyme denaturation and inactivation occur due to excessively high temperature, thus ensuring the stable operation of the nitrification system throughout the year.

[0025] In summary, this application has the following beneficial effects: 1. This application first classifies and breaks down the complexes in PCB wastewater to eliminate the chelating effect of complexing agents such as EDTA and citric acid on heavy metals. Then, it uses a two-stage chemical precipitation-filtration multi-stage process to retain heavy metals, reducing the toxicity and inhibition of heavy metals on subsequent biological bacteria. Then, it utilizes anoxic-aerobic biochemical combination process. The anoxic tank uses a composite functional bacterial community to achieve efficient denitrification and nitrogen removal, while the aerobic tank completes ammonia nitrogen nitrification and organic matter degradation. The nitrified liquid is returned to the anoxic tank for further removal of nitrate nitrogen. The entire process works synergistically to achieve simultaneous removal of heavy metals, COD, ammonia nitrogen, and total nitrogen, effectively improving the treatment instability caused by fluctuations in the quality and quantity of PCB wastewater and improving the effluent quality.

[0026] 2. In this application, the preferred method is to use a combination of Hansenula saturnii, Tauella tauren, and Thiobacillus denitrification. With the synergistic effect of each bacterium, the denitrification effect is significantly improved. Furthermore, the combination of Sphingosine monocytogenes, Bacillus subtilis, Nitrosomonas, and Nitrifying bacillus denitrification further enhances the degradation of organic matter, thereby improving the quality of the effluent.

[0027] 3. In this application, the preferred method is to specifically select the ratio of Hansenula sagittatum bacterial suspension, Tauerella salina bacterial suspension, and Thiobacillus denitrification bacterial suspension, as well as the ratio of Sphingomonas vesicatoria bacterial suspension, Bacillus subtilis bacterial suspension, Nitrosomonas nitrosamine bacterial suspension, and Nitrifying bacillus vesicatoria bacterial suspension. This method is conducive to the synergistic colonization and enrichment of Hansenula sagittatum, Tauerella salina, and Thiobacillus denitrification on the packing material, and also conducive to the synergistic growth of autotrophic nitrifying bacteria and heterotrophic functional bacteria. This results in a more stable biofilm formation and reduces the risk of domestication failure. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] Example 1 A process for treating wastewater from printed circuit board manufacturing includes the following steps: Step 1) Wastewater is classified, collected, and treated for chelation and water quality and quantity, as follows: Wastewater from printed circuit board (PCB) production is collected separately. Complexed wastewater is collected separately into a complex-breaking reaction tank. A sodium hypochlorite solution with an effective chlorine mass fraction of 10% is added to the complexed wastewater at a molar ratio of effective chlorine to complexed copper of 12:1. The reaction pH is controlled at 2.5-3.5, and the oxidation and complex-breaking reaction time is 2.5 hours. After the complex-breaking is completed, the pH of the system is adjusted to 8-9. After the total copper in the complex-breaking effluent is tested to be ≤1.5 mg / L, it is then combined with the remaining PCB wastewater and transferred to an equalization tank. The hydraulic retention time in the equalization tank is 12 hours. The tank is equipped with a stirring device to achieve water quality and quantity balance, resulting in balanced wastewater.

[0030] Step 2) Primary chemical precipitation treatment, as follows: The equalization wastewater is pumped into the primary chemical tank with a hydraulic retention time of 2.0 hours. First, 10% lime slurry is added to adjust the pH of the tank to 10.0-11.0. The mixture is then rapidly stirred at 300 rpm for 8 minutes. Next, ferrous sulfate is added at a dosage of 180 mg / L and stirred at 220 rpm for 5 minutes. Then, polyaluminum chloride is added at a dosage of 90 mg / L and stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at a dosage of 2.0 mg / L and stirred slowly at 60 rpm for 12 minutes. After the coagulation reaction is completed, the mixture is sent to an inclined tube sedimentation tank for solid-liquid separation. The sludge produced by the separation is discharged into a physicochemical hazardous waste sludge tank, and the upper effluent is the primary chemically treated water.

[0031] Step 3) Secondary chemical deep removal of heavy metals, as detailed below: The primary chemically treated water enters the secondary chemical tank with a hydraulic retention time of 2.0 hours. The tank is sealed and equipped with a tail gas collection device to maintain the pH in the tank at 9.3-10.0. First, a 15% sodium sulfide solution is added at a molar ratio of 1.8:1 to the residual total copper in the water. The mixture is rapidly stirred at 250 rpm for 10 minutes to precipitate the residual heavy metals as metal sulfides. Then, ferrous sulfate is added at 120 mg / L to remove excess sulfur ions from the system, and the mixture is stirred at 220 rpm for 6 minutes. Next, polyaluminum chloride is added at 70 mg / L, and the mixture is stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at 1.5 mg / L, and the mixture is slowly stirred at 55 rpm for 12 minutes. After the reaction, the mixture enters an inclined tube sedimentation tank to complete solid-liquid separation. The sludge is discharged into a physicochemical hazardous waste sludge tank to obtain the secondary chemically treated water. The residual sulfur ion concentration in the effluent from the secondary chemical tank is controlled to be less than 0.2 mg / L.

[0032] Step 4) Filtration and pH adjustment of pretreated water, as detailed below: Secondary chemically treated water is passed through a quartz sand filter to trap fine copper sulfide flocs. The filtered water is then tested. The pre-treated water indicators are controlled as follows: total copper ≤ 0.5 mg / L, total nickel ≤ 0.2 mg / L, and total zinc ≤ 1.0 mg / L. Water that does not meet the heavy metal standards is returned to the secondary chemical tank for retreatment. For qualified water, dilute sulfuric acid is added to adjust the pH to 7.0-8.0 to obtain pre-treated water.

[0033] Step 5) Anaerobic biochemical denitrification treatment, as detailed below: Pretreated water is fed into an anoxic biological treatment tank with a hydraulic retention time of 10 hours. The tank is filled with anoxic biological suspended packing material at a filling rate of 33%. The packing material has undergone acclimatization and inoculation treatment, and is enriched with Hansenula saturnii, Tauella tauri, and Thiobacillus denitrification. The dissolved oxygen in the tank is controlled online to be ≤0.5 mg / L. When the influent carbon-nitrogen ratio is less than 4.5, sodium acetate is added. The amount of sodium acetate added is calculated based on a carbon-nitrogen ratio of 5:1. To ensure the metabolic conditions of Thiobacillus denitrification, sodium thiosulfate is added quantitatively to control the reduced sulfur concentration in the system at 0.8-1.5 mg / L. The anoxic denitrification reaction is completed by hydraulic stirring, and the effluent is the primary biological treated water.

[0034] Microbial acclimatization and inoculation procedures: Polypropylene MBBR suspension packing is filled into the anoxic biological treatment tank. Then, Saturnian Hansenula polymorpha, Taurella multocida, and Thiobacillus denitrification is mixed at a volume ratio of 1.9:2.9:0.9 and added to the anoxic biological treatment tank. The total amount of mixed bacterial solution added is 800 mL per cubic meter of effective volume of the anoxic biological treatment tank. After inoculation, the initial small flow rate of influent is 30% of the system's designed full load flow rate for acclimatization. The acclimatization lasts for 7 days, and the influent flow rate is gradually increased in stages: 30% of the design flow rate on days 1-2, 50% on days 3-4, 70% on days 5-6, and 100% of the design full load on day 7. Before each increase in influent flow rate, the denitrification effect of the effluent in the previous stage is confirmed to be stable before increasing the load. If the effluent effect deteriorates, the current flow rate is maintained and operation continues. When a uniform light yellowish-brown slippery biofilm forms on the surface of the packing and the denitrification effect in the anoxic tank meets the design requirements, the biofilm formation on the packing is considered complete.

[0035] OD of Saturn Hansenula polymorpha 600 =1.0-1.2, OD of *Taurizoctonia solani* culture 600 =0.8-1, OD of Thiobacillus denitrification bacterial culture 600 =0.6-0.8.

[0036] Step 6) Aerobic aeration nitrification treatment, as detailed below: The primary biologically treated water enters the aeration biological treatment tank, which has a hydraulic retention time of 14 hours. The tank is filled with aerobic biological suspended packing material with a packing material filling rate of 28%. The packing material has been acclimatized and inoculated, and is enriched with Sphingomonas vegetans, Bacillus subtilis, Nitrosomonas nitrosamine, and Nitrosobacterium vegetans. The aeration system controls the dissolved oxygen in the tank to be 2.0-3.5 mg / L, and the system operates at a water temperature of 18-35℃.

[0037] The nitrified liquid is drawn from the aerated biological treatment tank and returned to the pre-deoxygenation tank. The hydraulic retention time of the pre-deoxygenation tank is 0.8 hours to reduce the dissolved oxygen carried by the returned liquid. After the pre-deoxygenation is completed, the nitrified liquid is returned to the anoxic biological treatment tank. The return ratio is set to 100%. The effluent from the aerated biological treatment tank is treated with secondary biological treatment.

[0038] Aerobic tank microbial inoculation procedure: Polypropylene MBBR suspension packing is filled into the aerated biological treatment tank. Then, *Sphingomonas vegetans*, *Bacillus subtilis*, *Nitrosomonas*, and *Nitrobacterium vegetans* bacterial solutions are mixed and added to the aerated biological treatment tank at a volume ratio of 0.9:0.9:1.9:1.9. The total dosage of the mixed bacterial solution is 1000 mL per cubic meter of effective volume of the aerated biological treatment tank. After inoculation, an initial low-flow influent is used for acclimatization at 30% of the system's designed full-load flow rate. The process lasted a total of 8 days, with the influent flow rate gradually increased in stages: Days 1-2 maintained at 30% of the design flow rate, Days 3-4 increased to 50% of the design flow rate, Days 5-6 increased to 70% of the design flow rate, and Days 7-8 increased to 100% of the design full load. Before each increase in influent flow rate, it was confirmed that the nitrification effect of the previous stage was stable before increasing the load. If the effluent indicators deteriorated, the current flow rate was maintained. When a uniform, yellowish-brown, slippery biofilm formed on the surface of the packing material, and the ammonia nitrogen nitrification effect in the aerobic tank met the design requirements, it was determined that the biofilm formation on the packing material was complete.

[0039] OD of Vibrio vesphingosine mononitrate culture 600 =0.8-1.0, OD of Bacillus subtilis bacterial culture 600 =1.0-1.2, OD of Nitrosomonas bacterial culture 600 =0.4-0.6, OD of *Nitrobacterium vesiculosus* bacterial culture 600 =0.4-0.6.

[0040] Step 7) Final sedimentation and sludge disposal, as detailed below: Secondary biological treated water is transported to the final sedimentation tank with a surface loading rate of 1.0 m³ / (m²・h). Polyaluminum chloride (50 mg / L) and anionic polyacrylamide (1.2 mg / L) are added sequentially. The mixture is stirred slowly at 50 rpm for 5 minutes and allowed to settle for 2.5 hours for solid-liquid separation. A sludge discharge outlet is set at the bottom of the sedimentation tank to periodically discharge the mixed sludge formed by the detached biofilm. A portion of the sludge is returned to the aeration biological treatment tank, and the remaining sludge is discharged into the biological sludge tank. The clear liquid at the top of the sedimentation tank is the treated purified water.

[0041] Physical and chemical sludge and biological waste sludge are collected together, dewatered by pressure filtration, and then disposed of by external parties as hazardous waste.

[0042] The Hansenula saponin was purchased from Beijing Bio-Bio Biotechnology Co., Ltd., platform number: BIO-099763.

[0043] The *Taugella* species is *Taugella limnophora*, purchased from Beijing Bio-Tech Biotechnology Co., Ltd., platform number: BIO-115098.

[0044] Thiobacillus denitrification was obtained from a commercially available source, international code: ATCC 25259.

[0045] Sphingosine monocytogenes was purchased from Beijing BioBio Biotechnology Co., Ltd., platform number: BIO-56705.

[0046] Bacillus subtilis was obtained from a commercially available source, international code: ATCC 23857.

[0047] Nitrosomonas was obtained from a commercially available source, international designation: ATCC BAA-1201.

[0048] Nitrifying bacteria were obtained from commercially available sources; international code: ATCC 25391.

[0049] Example 2

[0050] A process for treating wastewater from printed circuit board manufacturing includes the following steps: Step 1) Wastewater is classified, collected, and treated for chelation and water quality and quantity, as follows: Wastewater from printed circuit board (PCB) production is collected separately. Complexed wastewater is collected separately into a complex-breaking reaction tank. A sodium hypochlorite solution with an effective chlorine mass fraction of 10% is added to the complexed wastewater at a molar ratio of effective chlorine to complexed copper of 12:1. The reaction pH is controlled at 2.5-3.5, and the oxidation and complex-breaking reaction time is 2.5 hours. After the complex-breaking is completed, the pH of the system is adjusted to 8-9. After the total copper in the complex-breaking effluent is tested to be ≤1.5 mg / L, it is then combined with the remaining PCB wastewater and transferred to an equalization tank. The hydraulic retention time in the equalization tank is 12 hours. The tank is equipped with a stirring device to achieve water quality and quantity balance, resulting in balanced wastewater.

[0051] Step 2) Primary chemical precipitation treatment, as follows: The equalization wastewater is pumped into the primary chemical tank with a hydraulic retention time of 2.0 hours. First, 10% lime slurry is added to adjust the pH of the tank to 10.0-11.0. The mixture is then rapidly stirred at 300 rpm for 8 minutes. Next, ferrous sulfate is added at a dosage of 180 mg / L and stirred at 220 rpm for 5 minutes. Then, polyaluminum chloride is added at a dosage of 90 mg / L and stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at a dosage of 2.0 mg / L and stirred slowly at 60 rpm for 12 minutes. After the coagulation reaction is completed, the mixture is sent to an inclined tube sedimentation tank for solid-liquid separation. The sludge produced by the separation is discharged into a physicochemical hazardous waste sludge tank, and the upper effluent is the primary chemically treated water.

[0052] Step 3) Secondary chemical deep removal of heavy metals, as detailed below: The primary chemically treated water enters the secondary chemical tank with a hydraulic retention time of 2.0 hours. The tank is sealed and equipped with a tail gas collection device to maintain the pH in the tank at 9.3-10.0. First, a 15% sodium sulfide solution is added at a molar ratio of 1.8:1 to the residual total copper in the water. The mixture is rapidly stirred at 250 rpm for 10 minutes to precipitate the residual heavy metals as metal sulfides. Then, ferrous sulfate is added at 120 mg / L to remove excess sulfur ions from the system, and the mixture is stirred at 220 rpm for 6 minutes. Next, polyaluminum chloride is added at 70 mg / L, and the mixture is stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at 1.5 mg / L, and the mixture is slowly stirred at 55 rpm for 12 minutes. After the reaction, the mixture enters an inclined tube sedimentation tank to complete solid-liquid separation. The sludge is discharged into a physicochemical hazardous waste sludge tank to obtain the secondary chemically treated water. The residual sulfur ion concentration in the effluent from the secondary chemical tank is controlled to be less than 0.2 mg / L.

[0053] Step 4) Filtration and pH adjustment of pretreated water, as detailed below: Secondary chemically treated water is passed through a quartz sand filter to trap fine copper sulfide flocs. The filtered water is then tested. The pre-treated water indicators are controlled as follows: total copper ≤ 0.5 mg / L, total nickel ≤ 0.2 mg / L, and total zinc ≤ 1.0 mg / L. Water that does not meet the heavy metal standards is returned to the secondary chemical tank for retreatment. For qualified water, dilute sulfuric acid is added to adjust the pH to 7.0-8.0 to obtain pre-treated water.

[0054] Step 5) Anaerobic biochemical denitrification treatment, as detailed below: Pretreated water is fed into an anoxic biological treatment tank with a hydraulic retention time of 10 hours. The tank is filled with anoxic biological suspended packing material at a filling rate of 35%. The packing material has undergone acclimatization and inoculation treatment, and is enriched with Hansenula saturnii, Tauella tauri, and Thiobacillus denitrification. The dissolved oxygen in the tank is controlled online to be ≤0.5 mg / L. When the influent carbon-nitrogen ratio is less than 4.5, sodium acetate is added. The amount of sodium acetate added is calculated based on a carbon-nitrogen ratio of 5:1. To ensure the metabolic conditions of Thiobacillus denitrification, sodium thiosulfate is added quantitatively to control the reduced sulfur concentration in the system at 0.8-1.5 mg / L. The anoxic denitrification reaction is completed by hydraulic stirring, and the effluent is the primary biological treated water.

[0055] Microbial acclimatization and inoculation procedures: Polypropylene MBBR suspension packing is filled into the anoxic biological treatment tank. Then, Saturnian Hansenula polymorpha, Taurella multocida, and Thiobacillus denitrification is mixed in a volume ratio of 2:3:1 and added to the anoxic biological treatment tank. The total amount of mixed bacterial solution added is 800 mL per cubic meter of effective volume of the anoxic biological treatment tank. After inoculation, the initial small flow rate of influent is 30% of the system's designed full load flow rate for acclimatization. The acclimatization lasts for a total of 7 days, with the influent flow rate gradually increased in stages: 30% of the design flow rate on days 1-2, 50% on days 3-4, 70% on days 5-6, and 100% of the design full load on day 7. Before each increase in influent flow rate, the load can only be increased after confirming that the denitrification effect of the effluent in the previous stage is stable. If the effluent effect deteriorates, the current flow rate is maintained and operation continues. When a uniform light yellowish-brown slippery biofilm forms on the surface of the packing and the denitrification effect in the anoxic tank meets the design requirements, the biofilm formation on the packing is considered complete.

[0056] OD of Saturn Hansenula polymorpha 600 =1.0-1.2, OD of *Taurizoctonia solani* culture 600 =0.8-1, OD of Thiobacillus denitrification bacterial culture 600 =0.6-0.8.

[0057] Step 6) Aerobic aeration nitrification treatment, as detailed below: The primary biologically treated water enters the aeration biological treatment tank, which has a hydraulic retention time of 14 hours. The tank is filled with aerobic biological suspended packing material with a filling rate of 30%. The packing material has been acclimatized and inoculated, and is enriched with Sphingomonas vegetans, Bacillus subtilis, Nitrosomonas nitrosamine, and Nitrosobacterium vegetans. The aeration system controls the dissolved oxygen in the tank to be 2.0-3.5 mg / L, and the system operates at a water temperature of 18-35℃.

[0058] The nitrified liquid is returned to the aerated biological treatment tank via a return pipeline. The returned liquid is first sent to the pre-deoxygenation tank, where the hydraulic retention time is 0.8 hours to reduce the dissolved oxygen carried by the returned liquid. After the pre-deoxygenation is completed, the nitrified liquid is returned to the anoxic biological treatment tank with a return ratio of 150%. The effluent from the aerated biological treatment tank is treated as secondary biological water.

[0059] Aerobic tank microbial inoculation procedure: Polypropylene MBBR suspension packing was filled into the aerated biological treatment tank. Then, *Sphingomonas vegetans*, *Bacillus subtilis*, *Nitrosomonas*, and *Nitrobacterium vegetans* bacterial solutions were mixed in a volume ratio of 1:1:2:2 and added to the aerated biological treatment tank. The total dosage of the mixed bacterial solution was 1000 mL per cubic meter of effective volume of the aerated biological treatment tank. After inoculation, an initial low-flow influent was used as 30% of the system's designed full-load flow rate for acclimatization. The acclimatization process lasted for 8 days. The influent flow rate is gradually increased in stages: on days 1-2, the flow rate is maintained at 30% of the design flow rate; on days 3-4, it is increased to 50% of the design flow rate; on days 5-6, it is increased to 70% of the design flow rate; and on days 7-8, it is increased to 100% of the design full load. Before each increase in the influent flow rate, it is confirmed that the nitrification effect of the previous stage is stable before the load can be increased. If the effluent indicators deteriorate, the current flow rate is maintained. When a uniform yellowish-brown slippery biofilm forms on the surface of the packing material, the ammonia nitrogen nitrification effect in the aerobic tank reaches the design requirements, and the biofilm formation on the packing material is considered complete.

[0060] OD of Vibrio vesphingosine mononitrate culture 600 =0.8-1.0, OD of Bacillus subtilis bacterial culture 600 =1.0-1.2, OD of Nitrosomonas bacterial culture 600 =0.4-0.6, OD of *Nitrobacterium vesiculosus* bacterial culture 600 =0.4-0.6.

[0061] Step 7) Final sedimentation and sludge disposal, as detailed below: Secondary biological treated water is transported to the final sedimentation tank with a surface loading rate of 1.0 m³ / (m²・h). Polyaluminum chloride (50 mg / L) and anionic polyacrylamide (1.2 mg / L) are added sequentially. The mixture is stirred slowly at 50 rpm for 5 minutes and allowed to settle for 2.5 hours for solid-liquid separation. A sludge discharge outlet is set at the bottom of the sedimentation tank to periodically discharge the mixed sludge formed by the detached biofilm. A portion of the sludge is returned to the aeration biological treatment tank, and the remaining sludge is discharged into the biological sludge tank. The clear liquid at the top of the sedimentation tank is the treated purified water.

[0062] Physical and chemical sludge and biological waste sludge are collected together, dewatered by pressure filtration, and then disposed of by external parties as hazardous waste.

[0063] The Hansenula saponin was purchased from Beijing Bio-Bio Biotechnology Co., Ltd., platform number: BIO-099763.

[0064] The *Taugella* species is *Taugella limnophora*, purchased from Beijing Bio-Tech Biotechnology Co., Ltd., platform number: BIO-115098.

[0065] Thiobacillus denitrification was obtained from a commercially available source, international code: ATCC 25259.

[0066] Sphingosine monocytogenes was purchased from Beijing BioBio Biotechnology Co., Ltd., platform number: BIO-56705.

[0067] Bacillus subtilis was obtained from a commercially available source, international code: ATCC 23857.

[0068] Nitrosomonas was obtained from a commercially available source, international designation: ATCC BAA-1201.

[0069] Nitrifying bacteria were obtained from commercially available sources; international code: ATCC 25391.

[0070] Example 3

[0071] A process for treating wastewater from printed circuit board manufacturing includes the following steps: Step 1) Wastewater is classified, collected, and treated for chelation and water quality and quantity, as follows: Wastewater from printed circuit board (PCB) production is collected separately. Complexed wastewater is collected separately into a complex-breaking reaction tank. A sodium hypochlorite solution with an effective chlorine mass fraction of 10% is added to the complexed wastewater at a molar ratio of effective chlorine to complexed copper of 12:1. The reaction pH is controlled at 2.5-3.5, and the oxidation and complex-breaking reaction time is 2.5 hours. After the complex-breaking is completed, the pH of the system is adjusted to 8-9. After the total copper in the complex-breaking effluent is tested to be ≤1.5 mg / L, it is then combined with the remaining PCB wastewater and transferred to an equalization tank. The hydraulic retention time in the equalization tank is 12 hours. The tank is equipped with a stirring device to achieve water quality and quantity balance, resulting in balanced wastewater.

[0072] Step 2) Primary chemical precipitation treatment, as follows: The equalization wastewater is pumped into the primary chemical tank with a hydraulic retention time of 2.0 hours. First, 10% lime slurry is added to adjust the pH of the tank to 10.0-11.0. The mixture is then rapidly stirred at 300 rpm for 8 minutes. Next, ferrous sulfate is added at a dosage of 180 mg / L and stirred at 220 rpm for 5 minutes. Then, polyaluminum chloride is added at a dosage of 90 mg / L and stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at a dosage of 2.0 mg / L and stirred slowly at 60 rpm for 12 minutes. After the coagulation reaction is completed, the mixture is sent to an inclined tube sedimentation tank for solid-liquid separation. The sludge produced by the separation is discharged into a physicochemical hazardous waste sludge tank, and the upper effluent is the primary chemically treated water.

[0073] Step 3) Secondary chemical deep removal of heavy metals, as detailed below: The primary chemically treated water enters the secondary chemical tank with a hydraulic retention time of 2.0 hours. The tank is sealed and equipped with a tail gas collection device to maintain the pH in the tank at 9.3-10.0. First, a 15% sodium sulfide solution is added at a molar ratio of 1.8:1 to the residual total copper in the water. The mixture is rapidly stirred at 250 rpm for 10 minutes to precipitate the residual heavy metals as metal sulfides. Then, ferrous sulfate is added at 120 mg / L to remove excess sulfur ions from the system, and the mixture is stirred at 220 rpm for 6 minutes. Next, polyaluminum chloride is added at 70 mg / L, and the mixture is stirred at 180 rpm for 4 minutes. Finally, anionic polyacrylamide is added at 1.5 mg / L, and the mixture is slowly stirred at 55 rpm for 12 minutes. After the reaction, the mixture enters an inclined tube sedimentation tank to complete solid-liquid separation. The sludge is discharged into a physicochemical hazardous waste sludge tank to obtain the secondary chemically treated water. The residual sulfur ion concentration in the effluent from the secondary chemical tank is controlled to be less than 0.2 mg / L.

[0074] Step 4) Filtration and pH adjustment of pretreated water, as detailed below: Secondary chemically treated water is passed through a quartz sand filter to trap fine copper sulfide flocs. The filtered water is then tested. The pre-treated water indicators are controlled as follows: total copper ≤ 0.5 mg / L, total nickel ≤ 0.2 mg / L, and total zinc ≤ 1.0 mg / L. Water that does not meet the heavy metal standards is returned to the secondary chemical tank for retreatment. For qualified water, dilute sulfuric acid is added to adjust the pH to 7.0-8.0 to obtain pre-treated water.

[0075] Step 5) Anaerobic biochemical denitrification treatment, as detailed below: Pretreated water is fed into an anoxic biological treatment tank with a hydraulic retention time of 10 hours. The tank is filled with anoxic biological suspended packing material at a filling rate of 37%. The packing material has undergone acclimatization and inoculation treatment, and is enriched with Hansenula saturnii, Tauella tauri, and Thiobacillus denitrification. The dissolved oxygen in the tank is controlled online to be ≤0.5 mg / L. When the influent carbon-nitrogen ratio is less than 4.5, sodium acetate is added. The amount of sodium acetate added is calculated based on a carbon-nitrogen ratio of 5:1. To ensure the metabolic conditions of Thiobacillus denitrification, sodium thiosulfate is added quantitatively to control the reduced sulfur concentration in the system at 0.8-1.5 mg / L. The anoxic denitrification reaction is completed by hydraulic stirring, and the effluent is primary biological treated water.

[0076] Microbial acclimatization and inoculation procedures: Polypropylene MBBR suspension packing was filled into the anoxic biological treatment tank. Then, Saturnian Hansenula polymorpha, Taurella multocida, and Thiobacillus denitrification were mixed in a volume ratio of 2.1:3.1:1.1 and added to the anoxic biological treatment tank. The total amount of mixed bacterial solution added was 800 mL per cubic meter of effective volume of the anoxic biological treatment tank. After inoculation, the initial small flow rate of influent was set at 30% of the system's designed full load flow rate for acclimatization. The acclimatization lasted for 7 days, and the influent flow rate was gradually increased in stages: 30% of the design flow rate on days 1-2, 50% on days 3-4, 70% on days 5-6, and 100% of the design full load on day 7. Before each increase in influent flow rate, the denitrification effect of the effluent in the previous stage was confirmed to be stable before increasing the load. If the effluent effect deteriorated, the current flow rate was maintained and operation continued. When a uniform light yellowish-brown slippery biofilm formed on the surface of the packing and the denitrification effect in the anoxic tank met the design requirements, the biofilm formation on the packing was considered complete.

[0077] OD of Saturn Hansenula polymorpha 600 =1.0-1.2, OD of *Taurizoctonia solani* culture 600 =0.8-1, OD of Thiobacillus denitrification bacterial culture 600 =0.6-0.8.

[0078] Step 6) Aerobic aeration nitrification treatment, as detailed below: The primary biologically treated water enters the aeration biological treatment tank, which has a hydraulic retention time of 14 hours. The tank is filled with aerobic biological suspended packing material with a packing material filling rate of 32%. The packing material has been acclimatized and inoculated, and is enriched with Sphingomonas vegetans, Bacillus subtilis, Nitrosomonas nitrosamine, and Nitrosobacterium vegetans. The aeration system controls the dissolved oxygen in the tank to 2.0-3.5 mg / L, and the system operates at a water temperature of 18-35℃.

[0079] The nitrified liquid is returned through a pipeline from the aerated biological treatment tank. The returned liquid is first sent to the pre-deoxygenation tank, where the hydraulic retention time is 0.8 hours to reduce the dissolved oxygen carried by the returned liquid. After the pre-deoxygenation is completed, the nitrified liquid is returned to the anoxic biological treatment tank with a return ratio of 200%. The effluent from the aerated biological treatment tank is treated with secondary biological treatment.

[0080] Aerobic tank microbial inoculation procedure: Polypropylene MBBR suspension packing is filled into the aerated biological treatment tank. Then, *Sphingomonas vegetans*, *Bacillus subtilis*, *Nitrosomonas*, and *Nitrobacterium vegetans* bacterial solutions are mixed and added to the aerated biological treatment tank at a volume ratio of 1.1:1.1:2.1:2.1. The total dosage of the mixed bacterial solution is 1000 mL per cubic meter of effective volume of the aerated biological treatment tank. After inoculation, an initial low-flow influent is used for acclimatization at 30% of the system's designed full-load flow rate. The process lasted a total of 8 days, with the influent flow rate gradually increased in stages: Days 1-2 maintained at 30% of the design flow rate, Days 3-4 increased to 50% of the design flow rate, Days 5-6 increased to 70% of the design flow rate, and Days 7-8 increased to 100% of the design full load. Before each increase in influent flow rate, it was confirmed that the nitrification effect of the previous stage was stable before increasing the load. If the effluent indicators deteriorated, the current flow rate was maintained. When a uniform, yellowish-brown, slippery biofilm formed on the surface of the packing material, and the ammonia nitrogen nitrification effect in the aerobic tank met the design requirements, it was determined that the biofilm formation on the packing material was complete.

[0081] OD of Vibrio vesphingosine mononitrate culture 600 =0.8-1.0, OD of Bacillus subtilis bacterial culture 600 =1.0-1.2, OD of Nitrosomonas bacterial culture 600 =0.4-0.6, OD of *Nitrobacterium vesiculosus* bacterial culture 600 =0.4-0.6.

[0082] Step 7) Final sedimentation and sludge disposal, as detailed below: Secondary biological treated water is transported to the final sedimentation tank with a surface loading rate of 1.0 m³ / (m²・h). Polyaluminum chloride (50 mg / L) and anionic polyacrylamide (1.2 mg / L) are added sequentially. The mixture is stirred slowly at 50 rpm for 5 minutes and allowed to settle for 2.5 hours for solid-liquid separation. A sludge discharge outlet is set at the bottom of the sedimentation tank to periodically discharge the mixed sludge formed by the detached biofilm. A portion of the sludge is returned to the aeration biological treatment tank, and the remaining sludge is discharged into the biological sludge tank. The clear liquid at the top of the sedimentation tank is the treated purified water.

[0083] Physical and chemical sludge and biological waste sludge are collected together, dewatered by pressure filtration, and then disposed of by external parties as hazardous waste.

[0084] The Hansenula saponin was purchased from Beijing Bio-Bio Biotechnology Co., Ltd., platform number: BIO-099763.

[0085] The *Taugella* species is *Taugella limnophora*, purchased from Beijing Bio-Tech Biotechnology Co., Ltd., platform number: BIO-115098.

[0086] Thiobacillus denitrification was obtained from a commercially available source, international code: ATCC 25259.

[0087] Sphingosine monocytogenes was purchased from Beijing BioBio Biotechnology Co., Ltd., platform number: BIO-56705.

[0088] Bacillus subtilis was obtained from a commercially available source, international code: ATCC 23857.

[0089] Nitrosomonas was obtained from a commercially available source, international designation: ATCC BAA-1201.

[0090] Nitrifying bacteria were obtained from commercially available sources; international code: ATCC 25391.

[0091] Comparative Example 1 A wastewater treatment process for printed circuit board manufacturing differs from Example 2 only in that: The bacterial culture of *Candida utilis* was replaced with an equal amount of *Hansenula saturniensis*, the bacterial culture of *Paracococcus denitrificans* was replaced with an equal amount of *Tauella*, and the bacterial culture of *Thiobacillus denitrificans* was replaced with an equal amount of *Thiobacillus*.

[0092] OD of Candida utilis culture 600 =1.0-1.2, OD of Paracoccus denitrifying bacterial culture 600 =0.8-1, OD of Thiobacillus thiocyanate solution 600 =0.6-0.8.

[0093] The *Candida utilis* was sourced from commercially available sources, with the international code ATCC 22023.

[0094] The denitrifying paracoccus was purchased from Beijing Bio-Bio Biotechnology Co., Ltd., platform number: BIO-02824.

[0095] Thiobacillus thiocyanate was sourced from commercially available sources; its international designation is ATCC 23647.

[0096] Comparative Example 2 A wastewater treatment process for printed circuit board manufacturing differs from Example 2 only in that: The *Hansenula saturniensis* culture was replaced with an equal amount of *Candida utilis*.

[0097] OD of Candida utilis culture 600 =1.0-1.2.

[0098] The *Candida utilis* was sourced from commercially available sources, with the international code ATCC 22023.

[0099] Comparative Example 3 A wastewater treatment process for printed circuit board manufacturing differs from Example 2 only in that: Denitrifying paracocci replaced the Tauerella bacterial suspension in equal amounts.

[0100] OD of denitrifying paracoccal culture 600 =0.8-1.

[0101] The denitrifying paracoccus was purchased from Beijing Bio-Bio Biotechnology Co., Ltd., platform number: BIO-02824.

[0102] Comparative Example 4 A wastewater treatment process for printed circuit board manufacturing differs from Example 2 only in that: The bacterial solution of *Thiobacillus denitrification* was replaced with an equal amount of *Thiobacillus thiocyanate*.

[0103] OD of Thiobacillus thiocyanate solution 600 =0.6-0.8.

[0104] Thiobacillus thiocyanate was sourced from commercially available sources; its international designation is ATCC 23647.

[0105] Experiment 1 The same batch of wastewater was treated using the wastewater treatment processes employed in the various embodiments and comparative examples of printed circuit board manufacturing. The pH, SS (suspended solids), COD, and Cu content of the effluent were measured. 2+ (Total Copper), Ni 2+ (Total nickel), ammonia nitrogen, total nitrogen.

[0106] SS (suspended solids), COD, Cu 2+ (Total Copper), Ni 2+ The units for (total nickel), ammonia nitrogen, and total nitrogen are all mg / L.

[0107] Detection method: pH: GB / T 6920-1986; SS (suspended solids): GB 11901-1989; COD: HJ 828-2017; Cu 2+ (Total Copper): GB 7475-1987; Ni 2+ (Total Nickel): GB 11912-1989; Ammonia Nitrogen: HJ 535-2009; Total Nitrogen: HJ 636-2012.

[0108] The influent water quality and the purified effluent water quality of the experimental wastewater are detailed in Table 1.

[0109] Table 1

[0110] According to the data in Table 1, even with poor influent quality, all effluent indicators in each embodiment met the direct discharge limits for printed circuit board manufacturers as stipulated in GB39731-2020 "Electronic Industry Water Pollutant Discharge Standard". This demonstrates that the two-stage chemical precipitation combined with anoxic-aerobic biochemical processes significantly improves wastewater treatment efficiency. Furthermore, the denitrification efficiency of each embodiment is significantly superior to that of the comparative examples, with some comparative examples exceeding the discharge standards for total nitrogen. Therefore, the use of a combination of *Hansenula polymorpha*, *Daucus tauraceae*, and *Thiobacillus denitrificationus* can significantly improve denitrification and enhance effluent quality.

[0111] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A treatment process for wastewater from printed circuit board manufacturing, characterized in that: Includes the following steps: Step 1) Collect wastewater by category, break down the chelates, and adjust the water quality and quantity to obtain balanced wastewater; Step 2) Add lime, ferrous sulfate, polyaluminum chloride and polyacrylamide to the equalized wastewater, stir and react, then separate the solid and liquid, and the upper effluent is the first-level chemically treated water. Step 3) Add sodium sulfide, ferrous sulfate, polyaluminum chloride and polyacrylamide to the primary chemically treated water. After stirring and reacting, the solid and liquid are separated, and the upper effluent is the secondary chemically treated water. Step 4) After the secondary chemically treated water is filtered to remove fine heavy metal flocs, the pH is adjusted to 7.0-8.0 to obtain pretreated water; Step 5) Inject the pretreated water into the anoxic biological tank for anoxic denitrification treatment, and the effluent is the primary biological treated water. Step 6) The primary biologically treated water is injected into the aerated biological treatment tank for aerobic aeration nitrification treatment. The effluent is then used to obtain secondary biologically treated water. A portion of the effluent from the aerated biological treatment tank is returned to the anoxic biological treatment tank, with a return ratio of 100%-200%. Step 7) Inject the secondary biological treated water into the sedimentation tank, add polyaluminum chloride and polyacrylamide, stir and react, then separate the solid and liquid, and the upper effluent is the purified water. The anoxic biochemical tank is filled with anoxic biological suspension packing material, which is enriched with Hansenula saturnii, Tauella taurinae, and Thiobacillus denitrificationus. The aerated biochemical tank is filled with aerobic biological suspended packing material, which is enriched with Sphingosine monocytogenes, Bacillus subtilis, Nitrosomonas nitrosamines, and Nitrosobacterium vesiculosum.

2. The treatment process for printed circuit board manufacturing wastewater according to claim 1, characterized in that: In step 5), the filling rate of the anoxic biological suspension packing is 33-37%.

3. The treatment process for printed circuit board manufacturing wastewater according to claim 2, characterized in that: In step 5, the inoculation and acclimatization steps for the microbial strains in the anoxic biological suspension packing are as follows: Polypropylene MBBR suspension packing is filled into an anoxic biological tank. Then, Saturnian yeast solution, Tauella bacteria solution, and Thiobacillus denitrification bacteria solution are mixed and added to the anoxic biological tank at a volume ratio of 1.9-2.1:2.9-3.1:0.9-1.

1. The mixture is acclimated until a uniform yellowish-brown slippery biofilm forms on the surface of the packing, thus completing the biofilm formation on the packing.

4. The treatment process for printed circuit board manufacturing wastewater according to claim 3, characterized in that: The OD of the Saturn Hansenula polymorpha culture 600 =1.0-1.2, the OD of the *Taurizoctonia solani* bacterial culture 600 =0.8-1, the OD of the *Thiobacillus denitrification* bacterial solution 600 =0.6-0.

8.

5. The treatment process for printed circuit board manufacturing wastewater according to claim 4, characterized in that: In step 5), the dissolved oxygen in the pool is controlled online to be ≤0.5mg / L.

6. The treatment process for printed circuit board manufacturing wastewater according to any one of claims 1-5, characterized in that: In step 6), the filling rate of the aerobic biological suspension packing is 28-32%.

7. The treatment process for printed circuit board manufacturing wastewater according to claim 6, characterized in that: In step 6, the inoculation and acclimatization steps for the aerobic biological suspension packing are as follows: Polypropylene MBBR suspension packing is filled into the aeration biological treatment tank. Then, sphingomonas velutipes bacterial solution, Bacillus subtilis bacterial solution, Nitrosomonas nitrosamine bacterial solution, and Nitrosobacterium velutipes bacterial solution are mixed and added to the aeration biological treatment tank at a volume ratio of 0.9-1.1:0.9-1.1:1.9-2.1:1.9-2.

1. The mixture is acclimated until a uniform yellowish-brown slippery biofilm forms on the surface of the packing, thus completing the biofilm formation on the packing.

8. The treatment process for wastewater from printed circuit board manufacturing according to claim 7, characterized in that: The OD of the *Sphingomonas vesiculosus* bacterial suspension 600 =0.8-1.0, the OD of the Bacillus subtilis bacterial solution 600 =1.0-1.2, the OD of the Nitrosomonas bacterial culture 600 =0.4-0.6, the OD of the *Nitrobacterium vesiculosus* bacterial solution 600 =0.4-0.

6.

9. The treatment process for wastewater from printed circuit board manufacturing according to claim 8, characterized in that: In step 6), the dissolved oxygen in the aeration system is controlled at 2.0-3.5 mg / L, and the system operating water temperature is maintained at 18-35℃.

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