Chemical and microbiological studies on leachates from a waste tip.

SOME FACTORS affecting the chemistry and microbiology of waste tips are rainfall, surface water runoff, ground cover, types of tip and types of soil within the tip. Previous studies by Qasim & Burchinal (1970), on both simulated and natural tips, showed that anaerobic activity released CO,, H,, N, and CH,, and from acetone extracted tip solids, they obtained several aliphatic acids, ranging from acetic to isocaproic. As part of that study, Cook et al. (1 967) isolated from leachates, Escherichia, Bacillus, Lactobacillus, Streptomyces, Micromonospora, Thermomonospora, Nocardia and Clostridium spp. Isolated fungi consisted mainly of Aspergillus and Penicillium spp. Engelbrecht et al. ( 1 974) noted that faecal and total coliform counts of 103/ml, at 5 5 days in a simulated tip study, had decreased to 2-3 celldm1 at 110 days. Faecal streptococci persisted for 47 days after leaching began, but none could be found at 86 days. When they added faecal coliforms, faecal streptococci, Salmonella typhimurium and polio virus, the latter disappeared rapidly, but S. typhimurium outlived the other bacterial cells. The current study involved sample collections at four sites surrounding the 920 acre Cedarhills tip, located about 40 km southeast of the University of Washington campus. Established in 1964, at an altitude of 180 m, it has an annual rainfall of 100-125 cm and receives ca. 830 x lo3 kg/day solid wastes, consisting mainly of paper, animal and vegetable wastes, grass clippings, metal cans and glass.