EFFICIENCY OF FECAL BACTERIAL REMOVAL IN WASTE STABILIZATION PONDS IN KENYA

Results for faecal coliform die-off rates are presented for seven different waste stabilisation pond systems in Kenya, which were sampled as part of a national pond monitoring and evaluation study carried out during 1988-1989. The results showed that average die-off rates through each pond series were considerably lower than those predicted from traditional design equations which are based on temperature (Marais 1974). Die-off rates were surprisingly higher in the primary ponds, which are designed for BOD removal, than in the maturation ponds which are designed for pathogen removal. Good correlations were found between faecal coliform first order removal rate constants and (a) temperature for the pond series as a whole, and (b) influent faecal coliform concentration for individual ponds.