Abstract: A grit extractor includes inlet and outlet flumes arranged to inject and extract liquid tangentially into a round chamber. The velocity entering and leaving the chamber is controlled by the width of the outlet flume. The velocity is maintained within an optimal region over a ten to one flow range. An effective ten to one variation in flow is achieved with a velocity in the range of 1.5 feet per second to 3.5 feet per second.

Abstract: A submersible pump guide rail arrangement which utilizes the discharge conduit as the guide rail about which the submersible pump assembly is raised and lowered within a wet well. The discharge conduit is rectangular in cross-section and a guide means, having spaced apart V-shaped recesses, receives opposing corners of the discharge conduit thereinto.

Abstract: A method and apparatus for biological aerobic treatment of wastewater wherein oxygen is induced into a mixed liquor flow path and a method and apparatus for separating the liquid withdrawn from the mixed liquor flow path into a clear liquid stream and a flock laden stream. A streaming specific gravity separator of unique construction and operation separates the mixed liquor into a clear liquid stream and a flock laden stream, withdrawing the clear liquid stream from the system and directing the flock laden stream back into the mixed liquor flow path. The separator functions within the system to be self-controlling for load increases or decreases.In accordance with preferred embodiments of the system, the separator may be positioned inside or outside of an oxidation ditch. The separator may also be utilized in combination with an aeration basin.