Five new types of Lewabrane membrane-separation elements for reverse osmosis (RO) are now available. As of July, high-rejection (HR) types with membrane surface areas of 370 and 440 ft2, and high-flow (HF) types, with membrane surface areas of 370, 400 and 440 ft2 are available. The HR type elements are designed to provide extremely low salt passage in normal operation, with more than 99.7% salt rejection. The Lewabrane RO products are spiral-wound polyamide composite membranes, with standard lengths of 40 in. and diameters of either 4 or 8 in. The B090 HF 404 membrane element with 4-in. dia. has a unique ATD (anti-telescope devices) design at the end of the element, which extends the surface area of the membranes by almost 6% over other commercially available elements. This leads to higher water productivity. The permeate flowrate is 9.4 m3/d on average, with a salt rejection of 99.5%. — Lanxess AG, Leverkusen, Germany
New RO membranes with high salt rejection
| By Chemical Engineering