Do We Have To Sacrifice Performance To Be Green?

By Karen Lindsey, V.P. Operations, Avista Technologies, Inc.

The global use of membranes is widespread in municipal, industrial, and wastewater applications with reverse osmosis (RO) proving to be a highly effective and reliable method of advanced water treatment.  Reuse applications have been particularly challenging for water treatment chemical companies as these highly variable feedwaters can contain any imaginable constituent, resulting in a wide array of site specific foulants. 

By its nature, RO system flow paths result in diminishing feedwater flow rates along the collective series of elements which concentrates soluble minerals, microbes, and organic matter and eventually leads to membrane fouling.  As particles come out of solution and settle on membrane surfaces, they form a barrier layer that reduces permeate quality and flow and increases the pressure required to pass water through the membrane.  Fouling is inevitable, but proper cleaning can effectively restore permeate flow, increase rejection and reduce delta pressures so that treatment facilities continue to produce the desired water quantity and quality.