Cyclic Activated Sludge System (CASS) is a batch fill-and-draw activated sludge process operated in sequences of aeration and non-aeration which can effectively remove nitrogen and phosphorus.

• 循环活性污泥系统(CASS)是一种具有脱氮除磷功能的以序批曝气-非曝气方式运行的充-放式间隙活性污泥处理工艺。