Groundwater Contamination

Because percolate from SR and SAT land treatment can reach groundwater aquifers, the risk of pathogenic contamination must be considered. The removal of bacteria and viruses from the finer-textured agricultural soils used in SR systems is quite effective. A 5-year study in Hanover, New Hampshire, demonstrated almost complete removal of fecal coliforms within the top 5 ft of the soil profile (Reed, 1979). Similar studies in Canada (Bell and Bole, 1978) indicated that fecal coliforms were retained in the top 8 cm (3 in.) of the soil. About 90% of the bacteria died within the first 48 hr, and the remainder was eliminated over the next 2 weeks. Virus removal, which depends initially on adsorption, is also very effective in these soils.

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