Cause of Inefficient Solids Separation in the Activated Sludge Process

摘要

Research was conducted to examine why particles are contained in clarified effluent from activated sludge final sedimentation tanks which are not subjected to solids overload, since, in principle, particles should not exist above the feed-level of underloaded sedimentation tanks. Three aspects investigated on this study to assess the cause of solids loss were: closely-controlled pilot scale tests with a surrogate (calcium carbonate) suspension; examining solids properties captured/lost at full-scale activated sludge treatment plants; and operating a pilot-scale final sedimentation tank at an activated sludge wastewater treatment plant. High overflow rates caused a deterioration of pilot plant performance.