Three operational modes for removing glycerin from waste streams by reverse osmosis were examined. The three modes were: (1) a single-stage reverse osmosis unit which was demonstrated to be capable of removing 27% of the available glycerin, 92% of the inorganics, and 94% of the polyglycerines available in the feed; (2) a three-battey multi-stage unit with forward feed of the raffinate to subsequent reverse osmosis recovery batteries which provided a product stream containing 31% of the available glycerin, no inorganics, and 3.9% of the available polyglycerines; and (3) an alternate two battery multi-stage counter-current recovery unit which provided a waste stream containing 31% of the available glycerin, no inorganics, and 5.2% of the available polyglycerines. Membranes used were asymmetric cellulose acetate butyrate and cellulose acetate. Experimental pilot scale studies performed with tubular membrane models readily accommodated the sample plant stream being used. Optimum selectivity and good separation was achieved under operating pressures ranging from 600 to 800 psig. Product throughput rate appeared to be the limiting factor, being highly sensitive to both increased turbulence and reduced feed viscosities. A cost analysis of a typical multi-stage forward feed operation operated at 600 psig was estimated. Payout for the operation was 3.8 years at a 26% rate of return, making it an extremely favorable investment. (WRSIC abstract)

"March 1971." Includes bibliographical references (page 65).