Evaluating impact of fouling on reverse osmosis membranes performance

Membrane fouling is commonly defined as an undesirable formation of deposits on membrane surfaces and it is considered a major problem in most brackish, seawater, and waste water reclamation applications. Depending on nature of the scale and foulant, fouling processes will lead to decreased membrane fluxes, increased pressures needs, and/or increased permeate conductivity. In some cases, irreversible damage on membrane rejection properties may also occur. Membrane fouling will adversely affect reverse osmosis systems efficiency and result in increased operational costs and energy consumption. Although extensive research has been done in this field in the past, membrane fouling is an extremely complex process and still not fully understood. Historically, an important part of research conducted in membrane technology has been dedicated to understand fouling mechanisms in experiments designed to compare the effects of different variables in the behavior of one specific foulant (natural organic matter, colloids, etc.). There are fewer published works on fouling studies on membranes from actual operating plants which take into consideration the role of multiple composite fouling. In this article, results from over 500 membrane elements autopsied in Genesys membrane products laboratories in the last decade will be presented and reviewed. Statistical analysis will be used in order to establish relations between different types of foulants and factors affecting the fouling processes notably: feed water type/quality, pretreatment, operational conditions, and membrane position. The authors report the effects on membrane properties and performance derived from results of the autopsy procedure. They advocate the use of this technique to gain important data to improve the efficient operation of membrane plants.