The costs of maintaining good water quality were increasing at Gehl Guernsey Farms, a 100 year-old dairy in Germantown, WI. Cooling towers showed as much as 18 lb of dirt and debris, and the operating staff was forced to drain the towers and shovel out dirt three times per year. In addition, dip slid tests to check biological growth counts showed regular treatment was required. Gehl was using six drums of biocide chemicals per year - at a cost of $1,500 per drum - to keep the growth in check.
Screen filters, disposable cartridges, centrifugal separators and media filters were considered as solutions. Because 90% of the contaminants had a particle size of 10 Km or less, the filtering equipment selected had to be able to remove particles of this size. Cartridge filters could clean up the problem but were costly in terms of operating and maintenance. Centrifugal separators did not have the required removal efficiency, so media filters from Process Efficiency Products (PEP), Mooresville, NC, were selected.
Within the first month of installing PEP's media filter on the remote sump, the biological growth counts were reduced by 50%. Over time, Gehl has reduced its biocide usage to two drums per year, saving more than $6,000. The June bug problem that helped increase biocide usage also was reduced by the media filter.