Improvement of residuals treatment efficiency from water treatment plant by auto supernatant drain system

Recently, a novel system with high efficiency has been developed to drain only supernatant of residuals effectively from water treatment plant, which results in high removal efficiency in water treatment by enhancing the quality of residuals and recycling water. The system could positively cope with the variation of water quality by a monitoring device. It was also operated automatically by an auto-control program. The purpose of the present investigation is to evaluate the treatment efficiency of an auto supernatant drain system (ASDS) in treating the residuals from water treatment plant by operating pilot tests as well as column tests. The ASDS improved BOD of the water flowing into the residuals basin by 40.6% and that of the water flowing into the thickener by 90.8%. The improvement effect of COD by the system were 26.7% and 83.9% for the recycled water and the effluent, respectively. The system also improved 1.62 mgL−1 and 0.17 mgL−1 in terms of the mean TN and TP, respectively. The ASDS improved 4.56% of the mean moisture content and 87.3% of the mean recovery rate.