ProChemTech International Inc.'s chief chemist, Timothy Keister, CWT, has received US patent No. 7,595,000, "Operation of Evaporative Cooling Towers with Minimal or No Blowdown."

The Brockway, Pa., maker of water treatment products, says the patent discloses an effective, economical way to reduce evaporative cooling tower blowdown, which is wasted to the sewer. 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 use of bromine as a biocide for microbiological control. Combining the technology with a recently developed side-stream electrolytic bromine generator for control of microbiological growth represents reduces fresh water needs while eliminating use of biocides.

According to ProChemTech, economic analysis shows a typical payback of less than a 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 technology has been in operation for more than a year in an HVAC application, the USGBC LEED Platinum certified, Tempe Transportation Center Building in Tempe, Ariz.

ProChemTech expects the technology to be especially applicable for use in water-short areas of the country and anywhere that high-hardness make-up water sources limit the cycles of concentration that can be obtained in an evaporative cooling tower.