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Improvement of Activated Sludge Dewaterability by Electro-flotation  

Choi, Young-Gyun (대구대학교 환경공학과)
Park, Byung-Ju (대구대학교 환경공학과)
Park, Min-Jung (대구대학교 환경공학과)
Kim, Yun-Jung (서울대학교 지구환경시스템공학부)
Chung, Tai-Hak (서울대학교 지구환경시스템공학부)
Publication Information
Journal of Korean Society of Water and Wastewater / v.20, no.5, 2006 , pp. 677-684 More about this Journal
Abstract
Electro-flotation(EF), a novel sludge thickening method, could improve the dewaterability of activated sludge. The gas(microbubbles) generated during EF decreased the solid-liquid separation time below 1/5 of the time required for gravity sedimentation. In addition, over 90% of the sludge volume reduction could be achieved by EF although the settling characteristics of the sludge was very poor. The SRF(specific resistance to filtration) of the thickened sludge by EF was much lower than that of the sludge thickened by gravity sedimentation. The SRF of the thickened sludge decreased exponentially with increase of gas generation rate of the EF system. Gas generation rate could be controlled by varying the current density of the electrode. Degasing of the microbubbles by vigorous mixing of the thickened sludge layer deteriorated the dewaterability of the sludge. Therefore, it is obvious that the gas bubbles entrapped in the thickened sludge play a key role in the observed dewaterability improvement.
Keywords
dewaterability; electro-flotation(EF); gas generation rate; sludge thickening;
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