Ultra filtration is a pressure-driven purification process in which water and low molecular weight substances permeate a membrane while particles, colloids, and macromolecules are retained. Ultra filtration pore ratings range from approximately 1,000 to 500,000 daltons, thereby making UF more permeable than nano filtration.

UF membranes are composed of a polymer, such as poly sulfone or polyamide that is usually extruded into flat sheets or hollow fibres.

UF system is installed after completing the pre treatment with FBBR / SBR Activated sludge process to reduce the BOD level < 10mg/L. Ultra filtration system further treat the STP treated water with hollow fibre membranes and converts the water to suitable for toilet flushing , car washing , general floor cleaning etc.,