Replacement of Organic Biocides by Electrolytic Bromine - Sponsored Whitepaper

large zinc and aluminum die casting plant in Western Pennsylvania was using over $300 per week worth of proprietary isothiazolin and glutaraldehyde based organic biocides to control biological growth in one 16,000 gallon volume cooling tower system, the “ZDCW” system. Even at this high biocide dosage, control was borderline; the cooling water was very turbid with a strong septic odor. Controlling biological growth in this system was difficult due to significant contamination by overspray of die lube, which contains various surfactants and emulsified oils. The following table summarizes typical analytical results obtained on softened makeup and cooling water samples from this system as operated with organic biocides.

The plant operators and management were not pleased with either the results or the cost of the biological control program on this, or any of the other four cooling towers in the plant.

Solution We suggested in March, 2007, that the organic biocides could be totally replaced by electrolytic bromine generated on-site using a PCT ElectroBrom unit. Based on an initial sampling, we suggested trial installation of a Model EB-4, capable of producing up to 4 lb/day of bromine. The plant agreed to the trial proposal and a Model EB-4 was delivered and installed with start-up around July 1, 2007. Use of organic biocides was discontinued and after some experimentation the system was deemed to be in excellent biological control with a daily three hour dose of electrolytic bromine.

Results were deemed so good that a second electrolytic bromine unit was ordered for another 8,000 gallon volume cooling tower system, “ADCC”. This second unit, an MB-2.5 capable of generating 2.5 lb/day of bromine, was delivered and installed in early October, 2007.