Combined Chemical and Biological Treatment of Printed Circuit Board Wastewater

• Main Authors: Chien C. Liao, 廖建治
• Other Authors: Sheng H. Lin
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/71029691614854458805

碩士 === 元智大學 === 化學工程學系 === 90 === Printed circuit board (PCB) manufacturing process consumes a large quantity of high-purity water for surface cleaning. The process thus produces a great volume of wastewater, containing various salts and many metal and organic pollutants. The wastewater, if not properly treated, can be detrimental to the environment. The present study is to investigate treatment of PCB wastewater by combination of physical, chemical and biological methods, including chemical coagulation, electro-Fenton and sequencing batch reactor (SBR) method. Chemical coagulation was adopted as a pretreatment of the raw PCB wastewater. The important operating variables of chemical coagulation included the initial pH, PAC/polymer ratio and the amount of PAC were examined and operating conditions identified for efficient operations. The test results have indicated that removal of suspended solids, color and some organic compounds by the pretreatment is quite good. After chemical coagulation, the wastewater effluent was treated by electro-Fenton in a batch reactor to investigate the effects of operating variables, including the initial pH, current density, the amount of hydrogen peroxide and hydrogen peroxide input method, on the oxidation performances . The results have shown that removal of color and some non-biodegradable organic compounds is excellent. Finally, sequencing batch reactor (SBR) method was considered as a polishing step for final treatment of the wastewater effluent. Various SBR test runs revealed that the SBR method was able to lower the final wastewater COD to below 120 mg/L and ADMI below 100. In the kinetic studies, exponential, lumped and generalized kinetic models were adopted to model the electro-Fenton oxidation process. Best fit of these kinetic models was properly evaluated using the collected test data. The Eckenfelder kinetics of completely mixed type was adopted to model the biological reaction of the SBR process and the parameters of the model were empirically identified.