CASS,SBR pool began water Shi, with level constantly rose, decanter water device relies on buoy of buoyancy slowly of along oriented Rod floating, floating in water Shang, dang pool within began exposure gas Shi, decanter water device water mouth valve in close State, water mouth is located in buoy bottom, using exposure gas Shi produced of air will water mouth and exposure gas Shi produced of sludge isolation, effective to improve water.