Abstract: The center clarifier of an endless channel type activated sludge sewage treatment plant is provided with a steep conical floor, a conical baffle and a circular effluent launder. The upper periphery of the baffle includes an overflow trough to receive the scum which is allowed to collect between the trough and the tank wall. The feed to the clarifier is directed through a circular series of spaced submerged ports in the tank wall and toward the conical baffle below the scum collection zone to promote and allow separation of the scum which is removed by overflowing into the scum trough.

Abstract: A diffuser assembly of the general type for use in a municipal sewage treatment plant is of plastic and/or resin construction and includes spaced parallel or dual hanger pipes between the two rotary joints. The hoist arm extends between these hanger pipes to reach the lift joint. Opposed detent blocks between and engaging the dual pipes cooperate with a steady bracket into which the assembly is locked with a toggle action.

Abstract: The diffuser connector includes an elastic base part which is in the form of a tube adapted to be inserted into a round opening formed in the air header pipe wall. The connector also includes a rigid insert having a stem which, when pushed through the base, flares the tube to form a grommet which secures the base to the pipe. A cooperating detent means between the base and the insert at the same time secures the latter to the base. The connector provides the quick securement of the diffuser to the pipe with the required air seal therebetween and does not require threading or any other finishing of the pipe opening. The diffuser may comprise separable parts, one of which includes the insert and the other includes the air outlets.