Over the past several years, Separation Dynamics International (SDI), of Farmington Hills, MI, has developed and patented a separation process which is extremely effective and economical in recycling of aqueous parts washing solutions. This process is based on a cellulose membrane technology, EXTRAN™, which has major technical and commercial advantages over other approaches that have been tried for this application.The EXTRAN Recycling System is designed to continuously clean the fluid in an aqueous parts washer. The results are dramatically improved parts washing performance, re-use of valuable cleaning chemicals, minimized waste, and reduced labor. The unique cellulose membrane allows these benefits to be realized without the operational difficulties traditionally associated with conventional membranes. This system has been successfully field tested during the past two years using both pilot scale and commercial systems.