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In order to reduce the concentration of contaminants in HVAC cooling towers, a substantial amount of water must be periodically discharged. However, this discharged water, or blowdown, contains anti-scalant, anti-corrodant and an-ti-microbiological toxic chemicals used to control scaling, fouling and corrosion. The blowdown is discharged into local sewage or stormwater systems and ultimately into the environment. Some municipal sewer agencies charge a fee to accept the discharged water from buildings because it contains hazardous materials that must be treated.

Key Facts

  • While high-efficiency cross-flow microsand filtration (CMF) is a uniquely effective solution for reducing fouling, according to research by Eneref Institute only about 15% of all US commercial buildings use CMF systems in their cooling towers.
  • Unlike total dissolved solids, total suspended solids (TSS) can be reduced by filtration. Reducing TSS makes chlorine and other disinfectants more effective, allowing chemical treatments to be reduced by as much as 35%.
  • In the United States, Legionnaires’ disease is fairly common and serious—one of the top three causes of non-epidemic, community-acquired pneumonia. According to US Dept of Labor, OSHA estimates that over 25,000 cases of the illness occur each year, causing more than 4,000 deaths. Only preventive measures, such as more effective water filtration, can minimize the potential for Legionella outbreaks.
  • CMF systems require less than 5% of the cooling tower water to flow into the filtration media at a time. Traditional technologies may require up to 30% of the cooling tower flow. The shallower bed of CMF systems also requires 50% less water for backwash than traditional deep-bed systems.