SUPERNATANT WATER DISCHARGE APPARATUS OF BATCHWISE SEWAGE TREATMENT TANK

摘要

PURPOSE:To prevent suction of supernatant water along with settled activated sludge to be discharged when supernatant water is drained after org. sewage mixed with activated sludge is subjected to biological reaction treatment. CONSTITUTION:A bottomed cylindrical pump receiving cylinder 5 is vertically inserted in a batchwise sewage treatment tank 1. The upper end of the pump receiving cylinder 5 is made higher than the highest water level H at the time of the injection of sewage and the lower end thereof is made lower than the lowest level L after supernatant water is drained. An auxiliary cylinder 9 is provided so as to be superposed on the outside of the pump receiving cylinder 5 in a revolvable manner. Arrangement slits 16a, 16b crossing each other are provided to the peripheral walls of both cylinders 5,9 and the crossing position thereof is set to a drain port 17. The auxiliary cylinder 9 is rotated to allow the drain port 17 to be lowered so as to follow the water level.