To ensure sufficient thermoelectric power production in the future, the use of alternative water sources to replace freshwater consumption in power plants will be required. The amount of municipal wastewater (MWW) being produced and its widespread availability merit the investigation of this potential source of cooling water. This is particularly important for thermoelectric power plants in regions where freshwater is not readily available. Critical regulatory and technical challenges for using MWW as makeup water in recirculating cooling systems are examined. The existing regulations do not prohibit wastewater reuse for power plant cooling. The challenges of controlling corrosion, mineral scaling, and biofouling in recirculating cooling systems need to be carefully considered and balanced in a holistic fashion. Initial investigations suggest that many of these challenges can be surmounted to ensure the use of MWW in recirculating cooling systems.

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Secondary treated municipal wastewater is a promising alternative to fresh water as power plant cooling water system makeup water, especially in arid regions. Laboratory and field testing was conducted in this study to evaluate the corrosiveness of secondary treated municipal wastewater for various metals and metal alloys in cooling systems. Different corrosion control strategies were evaluated based on varied chemical treatment. Orthophosphate, which is abundant in secondary treated municipal wastewater, contributed to more than 80% precipitative removal of phosphorous‐based corrosion inhibitors. Tolyltriazole worked effectively to reduce corrosion of copper (greater than 95% inhibition effectiveness). The corrosion rate of mild steel in the presence of free chlorine 1 mg/L (as Cl2) was approximately 50% higher than in the presence of monochloramine 1 mg/L (as Cl2), indicating that monochloramine is a less corrosive biocide than free chlorine. The scaling layers observed on the metal alloys contributed to corrosion inhibition, which could be seen by comparing the mild steel 21‐day average corrosion rate with the last 5‐day average corrosion rate, the latter being approximately 50% lower than the former.

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The gravimetric weight loss method and the electrochemical polarization resistance methods were combined to evaluate instantaneous corrosion rates for metals and metal alloys in industrial cooling-water systems. Metal and metal−alloy samples were exposed to synthetic cooling water in a bench-scale recirculating system constructed to study corrosion under flow conditions similar to those of a cooling-water system. The measurements yielded by both methods were related through a coefficient, B′, to convert polarization resistance measurements to instantaneous corrosion rates. The metals and metal alloys tested in this study included mild steel, aluminum, copper, and cupronickel. B′ was observed to change with time initially but approach a constant value for long-term exposure (>3 days) for most metal materials. B′ values varied with metal or metal alloy studied. It was concluded that combining both methods to determine the B′ value for a metal or a metal alloy under particular exposure conditions provides a means of obtaining an accurate instantaneous corrosion rate.