During the second quarter of 2004, following several years of drought in Colorado, two vintage
coal-fired power plants began using reclaimed water in their main condenser cooling systems instead
of fresh water and drinking water. The first power plant had a smooth transition from fresh water to
reclaimed water, uses only sulfuric acid and sodium hypochlorite for cooling water treatment and is
very satisfied with the results. However, this has not been the case with the second power plant. The
transition from drinking water to reclaimed water resulted in biofouling and iron deposition issues and
the plant reverted to drinking water until the problems could be solved. This led to a multi-phase test
run of the tertiary treatment plant, as well as changes in cooling water treatment at the power plant to
overcome these serious issues. This paper will explore why these two reclaimed water case histories
have had such different experiences even though the power plants and reclaimed water production
facilities are very much alike.