Design and operation of a 5000 m 3/d reverse osmosis dual product plant

Abstract

A dual product quality plant was designed and commissioned to supply 3000 m 3/d of very high quality product plus 2000 m 3/d of medium quality product from a single RO process train. In this plant, the high purity product from the first bank may be diverted directly to the end use without further treatment, while the lower purity water from the second and third banks is polished in an existing D.I. plant to supply required ultrapure water. By processing only a portion of the RO product in a D.I. train, a large savings in operating and capital costs were realized. A present-worth analysis showed the ratio of present value to cost to be 3.1 with a payout time of 1.1 year based on comparison with D.I. alone. Original design values for the plant were: Feedwater Quality 1940 ppm as CaCO 3 1st Bank Product 20–25 ppm as CaCO 3 2nd & 3rd Bank Product 30–45 ppm as CaCO 3 Hydraulic Recovery Rate 82% Installed Electric Power 320 Kw