Timothy Keister, CWT, the chief chemist at ProChemTech International Inc., Brockway, Pa., has received U.S. patent No. 7,595,000 for “Operation of Evaporative Cooling Towers with Minimal or No Blowdown.”

The patent discloses a means to reduce blowdown — water wasted to sewer — from operation of evaporative cooling towers. The technology involves softening of the makeup water, use of a specific chemistry to control the high corrosivity of concentrated soft water, bypass filtration, and the use of bromine as a biocide for microbiological control. The combination of this technology with the company’s side-stream electrolytic bromine generator for control of microbiological growth reduces cooling tower fresh-water needs while eliminating use of toxic biocides, according to ProChemTech.

Economic analysis shows a typical payback of less than one year on required equipment and reductions of up to 25 percent in fresh makeup water use and a 70 percent or better reduction in water discharge to sewer, the company says. The technology has been in operation for more than a year at the Tempe Transportation Center Building in Tempe, Ariz.

ProChemTech says it anticipates the technology will be especially applicable for use in water-short areas of the country and where high hardness makeup water sources limit the cycles of concentration that can be obtained in an evaporative cooling tower.