Case Study: ZwitterCo RO Reduces Cleaning Frequency by Over 70% at US-Based Power Plant
Water is a critical component of power generation – in conventional power plants, water is heated to transform it into steam, which then spins the turbines that produce electricity. To meet their high-water demands, plants are often located near rivers, lakes, or oceans, where surface water contains impurities like suspended solids, bacteria, algae, and natural organic material (NOM). These must be removed before make-up water enters the boilers. Pretreatment methods are used to remove larger floating and suspended materials, reverse osmosis (RO) membrane elements are implemented to remove dissolved solids, and usually, downstream ion exchange systems are used to polish the water further before it is sent to the boilers. Despite pretreatment, surface water’s high organic and biological content may cause organic fouling and biofouling in RO systems. Organic deposits on membranes may lead to a decline in RO system performance, requiring chemical cleaning. The more fouling the feed stream, the more frequent cleanings are required, leading to increased downtime, shorter membrane life, and higher operating costs.
The Challenge
A power plant in the Northwestern U.S. treats organic-laden river water for boiler make-up. Despite extensive pretreatment, organic fouling remains a challenge, causing frequent maintenance and downtime and ballooning operating costs. The plant performs chemical cleanings monthly or more and replaces RO elements every 12–18 months when they no longer meet water quality or production objectives. The site had also experienced a major fouling event that caused unexpected downtime which forced it to rent mobile units to keep the power plant running, costing tens of thousands of dollars in operating expenses. Because reliable water production is critical for power generation, the plant aimed to find a more economical solution that could reduce the frequency of chemical cleaning, improve system uptime, and extend membrane lifespan.