Study on Development of Automatic Control Sequencing Batch Reactor for Treating Heavy Metal Wastewater by Chemical Precipitation

• Main Authors: Luoh Ming-Yung, 駱明永
• Other Authors: Tseng Dyi-Hwa
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/39660566959487868672

碩士 === 國立中央大學 === 環境工程研究所 === 83 === The purpose of this study was to develope an automatic control sequencing batch reactor (SBR) for chemical precipitation of heavy metals fromelectroplating wastewater. A capacity of 2 cubic meters pilot-scale SBR facility was installed at a plating factory whose wastewater mainly contain Cr,Zn and Fe with the concentration in about 150 mg/l, 450 mg/l and 120 mg/ l, respectively. For a long term on-site test run, the treatment efficiency for heavy metal removal was investigated and the operatingstrategies of SBR were evaluated. The results indicated that the effluent concentration of heavy metals, including Cu, Zn, Cr and Fe, could be treated to as low as to meet the National Effluent Standard of 1998 no matter what operating strategies were employedin this study. There are several discrete operational periods were established during one cycle for each sequencing batch treatment of the plating wastewater.The periods were fill/pH adjustment/rapid mix, slow mix (flocculation), settle, draw, and idle/waste sludge in a time sequence. Idle and/or waste sludge could be eliminated depending on requirements of the treatment problem. When sludge accumulated in the reactor to a high concentration resulted in slow settlingvelocity or poor effluent quality, a portion of sludge should be wasted. Under normal operation condition, the SBR could serve as storage and thicking ofsludge in addition to chemical reaction. The experimental results showed thatthe thickened sludge concentration could be up to 6% of TS. For better sludge storge and thickening, it is suggested that the height of drainage nozzle would be located at 1/3 - 1/2 of the effective height from the bottom of SBR.