Wastewater reuse as cooling-tower makeup: Final report

The objectives of this program are to document electric utility experience and concerns on the use of municipal wastewater as makeup to cooling towers and to identify areas lacking sufficient information for their application as well as to identify problem areas. Current users of municipal wastewater in electric utility cooling towers have been contacted and the literature has been reviewed. In addition, literature on the reuse of industrial wastewater has been reviewed. The findings are summarized in this report with emphasis on the use of municipal wastewater in electric utility cooling towers. It was found that this practice has been going on for sufficient time at sufficient places that the problems are fairly well understood. Scale formation by calcium phosphate is a problem. It is controlled by pH reduction or by removal of phosphate and suggested techniques are given. Fouling by slime is a problem. It is controlled by heavy doses of chlorine and other biocides or by mechanical and other non-chemical means without use of any biocide. Foaming, corrosion and blowdown disposal are not problems. There are a number of problem areas where more information is desired to establish a higher level of confidence in using sewage water asmore » makeup. Three areas of research are recommended: (1) a study comparing the technological and environmental problems and costs of various technologies used to control the formation of biological slime, (2) laboratory and pilot scale testing to verify the prediction techniques for phosphate precipitation, and (3) to determine whether the health hazards of using sewage water are worse than the use of normal waters.« less