Treatment Of Printed Circuit Board (PCB) Wastewater By Interior Microelectrolysis-Heary Meatals Capturing-Sedimentation-Biological Contact Oxidation-Adsorption Integrated Process

Printed circuit board （PCB） wastewater is suggested as one of the major pollution fromthe machinery and electronics industries. Large amount of substandard effluent generatedduring the PCB manufacturing poses great threat to the environment. Treatment of theeffluent to meet the national discharge standard and further advanced treatment for resourcesrecovery are of strong interest to the researchers and industries.No-breakable complexes, high concentrations of heavy metals and ammonia pose a greatchallenge to conventional treatment techniques treatment for printed circuit board （PCB）contained wastewater. In this study, an integrated process of interior microelectrolysis andheavy metals capturing and biological contact oxidation was developed to treat PCBcontained wastewater. This integrated treatment is sufficient and cost-effective for treatmentof PCB contained wastewater and show a great potential for reduction and resourcesrecovery/reuse of wastewater discharged from the machinery and electronics industries.In present study,（Ⅰ） the PCB wastewater was characterized.The disadvantages ofconventional technology for PCB wastewater treatment were analyzed and then the integratedtreatment process was proposed;（Ⅱ） the key aspects of the design and operation of theprocess were identified based on the knowledge of interior microelectrolysis, heavy metalscapturing and biological contact oxidation （BCO）, respectively;（Ⅲ） the pilot/field studieswere conducted in a PCB manufacturer in Guangzhou Economic and TechnologicalDevelopment Zone （Demonstration Project）, and operation conditions were optimized;（Ⅳ）according to the field study, conclusion and evaluation for technology and economic returnswere made.In the field study, average concentrations of COD, Cu²⁺, Ni²⁺and ammonia nitrogen inthe effluent forn the secondary sedimentation tank were28.84mg/L,0.47mg/L,0.014mg/L,respectively, which well above the national first-grade discharge standard for sewage （GB8978-1996） and Guangdong local sewage discharge standard （DB44/26-2001）. The effluentafter advanced treatment could be reused separately because the benzene, methylbenzene,dimethylbenzene and phenyl ethylene were almost completely removed （0.19μg/L、0.13 μg/L、0.15μg/L and0.09μg/L for each）. The effluent quality can meet the standard for reuseof urban recycling water, such as the standard of urban miscellaneous water consumption（GB/T18920-2002）, scenic environment use （GB/T18921-2002）, and industrial uses（GB/T19923-2005）.The capital investments for reduction and advanced treatment of the PCB wasetwater are2426and159RMB/ton wastewater wihle total operating costs are2.020and0.507RMB/ton,respectively. Compared with conventional wastewater treatment technology, the integratedsystem can bring considerable economic returns since the reduction in operating cost isestimated to be423,400RMB/year as a whole. Additionally, the tower-type constructors havethe advantages of small space occupation, automatic operation, limited training formanagement and no-daily operation. Therefore, the integrated process is of great potential fortreatment of wastewater discharged from PCB industries.