Fate and Enumeration Problems of Fecal Coliform Bacteria in Runoff Waters from Terrestrial Ecosystems

摘要

Field and greenhouse model tests were conducted, using both natural wastewater or tracer fecal coliform bacteria as overland flow system inocula. Greenhouse models contained soils previously uncontaminated or contaminated by human versus cattle fecal wastes: application rates were varied to determine best treatment conditions. The fecal coliform (M-FC) test isolates were identified to determine their origin, fate, and enumeration problems. Modifications to the standard method for fecal coliform testing were conducted to develop improved testing methodology. Escherichia coli was considered the best indicator bacterium for assessing recent fecal pollution and disease potential of overland runoff. The e. coli plate counts were highest in effluent runoff during the hot summer and above-freezing fall period. Enumeration problems of E. coli were less severe during the cool weather because of great reductions in interfering bacteria on test plates at this time. Field and greenhouse observations indicated that the continuously treated plots provided better conditions for protozoan predation of fecal bacteria and also for the development of a surface organic layer on the plots that aided in the removal of wastewater bacteria through filtration and entrapment.