Abstract: A method and apparatus for recycling water based workpart cleaning fluid of the type used to wash workparts (B) free of soils, such as emulsified and non-emulsified cutting oils and lubricants, particulate matter and other hydrophobic fluids. A parts washer (12) is provided for cleaning workparts (B) contaminated with soils. The contaminated cleaning fluid is discharged from the parts washer (12) in a slip stream and directed to a process tank (22). The contaminated cleaning fluid is pumped from the process tank (22) to a prefilter (28) where large particles are screened. The cleaning fluid is then directed to regenerated cellulose membrane filters (34) where the water based cleaning fluid and the hydrophilic water soluble substances in the base, i.e., the detergents, are imbibed through the membrane (34) as permeate while the soils pass as retentate. The permeate is returned to the parts washer (12), whereas the retentate is directed back to the process tank (22).

Abstract: An apparatus and process for treating water contaminated with hydrocarbons utilizes a dual membrane apparatus wherein contaminated water is first treated by a cellulose based membrane to produce a permeate fraction that is clarified and has a reduced content of hydrocarbons. The clarified permeate fraction is then treated with a reverse osmosis or nanofiltration membrane to produce a purified permeate water having an additionally lowered content of hydrocarbons.