소규모 하수처리시설에서의 현장 슬러지 퇴비화를 위한 전처리 방법에 관한 연구

Abstract

This study is on the pretreatment of on-site sewage sludge composting at small-scale sewage treatment plant to minimize phosphorus release from the long term storage of excess sludge at storage tank. Composting of sewage sludge which has as high as 99 % of water content requires dewatering process, but small-scale sewage treatment plant is difficult to install and operate dewatering process. In this study, substituting dewatering process, gravitational thickening for 30 hours was installed and 96 % of sludge water content was achieved. To compost sewage sludge, which has high water content and low C/N ratio, thickened sludge was mixed with woodchip to reach water content in the range of 60~70 %, and external heat was supplied for 9 days with aeration to maintain internal temperature of composting reactor in the range of 50~55 ℃. Combination of gravitational thickening, control of initial water content in the range of 60~70 % with woodchip, and external heating for 9 days during 2 weeks aeration can stabilize sewage sludge, and this on-site composting could reduce phosphorus release at the sludge storage tank in small-scale sewage treatment plant.