2 Decades Constructed Wetland Experience in Treating Municipal Effluent for Power Plant Cooling at the Shand Power Station, SaskPower Part I: A Review on the Rationale

Emmanuel K. Quagraine



With increasing water shortages, power plants in particular are pinged and are being compelled to consider the reuse of treated municipal wastewater (MWW) for steam condenser cooling. The use of such reclaimed water however poses its own challenges including operational issues such as scaling, corrosion and biofouling that have serious cost implications as well as environmental and health concerns. Post-treatment of the usually permitted secondary effluent for reuse applications is typically required or otherwise to operate with these consequences. Constructed Wetland (CW) is a relatively new technology that holds promise for such post-treatment to make the effluent more fit for the cooling water application and minimize such associated risk, but its actual commercial-scale application within the power industry is still wanting, although there are recent intense interests for such application. The Shand Power Station of SaskPower, is one Canadian example, which has since 1994 been using CW as tertiary treatment of municipal effluent, which constitutes a dominant portion of the Cooling Tower (CT) re-circulating make-up water during the warmer months. The paper is the first of a series of publications that seek to broadly outline experiences and lessons learnt with CW as treatment technology in polishing municipal effluent for reuse in power plant cooling, whilst also highlighting other capabilities inherent in the technology for enhancement in this application. Specifically, this current paper reviews the literature on municipal effluent quality and the concerns and limitations associated with its reuse in power plant cooling; CWs performance in treating various municipal effluent qualities; current CW treatment applications within the power industry; and lastly discusses the associated benefits as rationale for why SaskPower would have adopted this technology 2-decade ago.