State-of-the-art of reverse osmosis desalination pretreatment

Pretreatment plays the critical role of removing source water constituents, like sediment and microbes, which could hinder the downstream reverse osmosis (RO) desalination process. While some source waters require negligible pretreatment, others like surface waters, require rigorous treatment to protect the RO process operation. The RO industry grew rapidly between 1995 and 2010. Growth pushed the industry to find cost-effective and robust large-scale pretreatment solutions. Over the last two decades, RO manufacturers have also developed membranes with greater fouling resistance and advocated system designs that reduce fouling potential. As a result, the state of the art in pretreatment has progressed significantly since the mid 1990s. Many of the improvements in pretreatment were enabled by a better understanding of fouling processes. Because fouling is complex and dynamic, with biofouling contributing to its complexity, significant research and development have been necessary to identify improvements. This paper provides a basis to understand the various fouling mechanisms found in RO systems and to describe the current state-of-the-art of the pretreatment technologies for fouling control. The paper addresses pretreatment of the myriad water sources in which RO technology is applied, with greater emphasis on seawater RO SWRO pretreatment as the largest single pretreatment market segment. (C) 2014 Elsevier B.V. All rights reserved.