A Low-cost, Safe, Effective Halogen Disinfectant for Cooling Towers

On-site, on-demand generation of MIOX mixed oxidant disinfecting solution provides several advantages for the cooling tower industry. These include excellent control of microbial populations even at the elevated pH typical of cooling tower waters, no negative impact on traditional scale and corrosion inhibitors, and environmentally friendly operating conditions. As an inherently safe technology, it only uses common sodium chloride salt as a feed stock. The solution can be fed directly to the cooling tower and controlled via Oxidation Reduction Potential (ORP). Case studies demonstrate significant reductions in operational costs when compared to conventional biocide chemicals, not only on a commodity cost basis, but also for elimination of safety related costs. This paper uses case studies and laboratory data to demonstrate mixed oxidant advantages for cooling tower disinfection. Introduction The cooling industry must address five major challenges for cooling tower maintenance. They include traditional issues such as 1) controlling inorganic scale deposition on cooling surfaces (Ca Co3, CaSo4 and silica deposits), 2) providing corrosion protection for steel, copper, copper/nickel tubing, and cooper alloys (admiralty), 3) controlling microbiologic growth, including biofilms on cooling surfaces and bacterial counts in the cooling tower basin water, 4) preventing fouling in heat exchangers and condensers and 5) controlling airborne impurities and contaminants that enter external to the water source. More recently, disease outbreaks caused by the aerosolization of waterborne bacteria from inadequately managed cooling towers have caused concern and, in some cases, legal action. The cooling industry addresses many of these traditional challenges through chemical addition programs using various combinations of antiscalants, corrosion inhibitors, dispersants, biocides, and the use of disinfectant(s) to provide a free halogen residual. Chemical disinfection of the water is the primary means for controlling biological growths and biofouling, in conjunction with other physical process such as settling and filtration. Bulk hypochlorite (chlorine), bromine and/or combinations of bromine and chlorine are often used to control bacterial growth and provide the disinfection residual, in addition to use of costly specialty organic biocides and algecides. However, regulatory trends at both the state and federal level concerning the safe and secure transport, storage and use of biocides, are pushing the industry to consider safer, less costly technologies. Regulatory drivers include chemical security regulations, registration of chemicals and mil taxes in some states, and biocide discharge residues of cooling tower blowdown. Meeting new regulations can be costly and time-consuming.