Profile: Purestream, Inc. manufactures standard biological wastewater treatment products, such as extended aeration , sigma low speed surface aerators, rotating biological contactors (RBC's) and sequencing batch reactors (SBR's). We offer the advanced biological treatment solution. The In-Eko Screw Screen that we provide is available in 304 stainless steel and fiberglass reinforced plastic. It is designed for smaller flow applications with opening sizes ranging from 1 to 12 mm.