Guidelines for the minimum evaluation of the performance of full-scale waste stabilization pond systems

Abstract

Guidelines are presented for the minimum evaluation of the performance of existing full-scale waste stabilization ponds. It is recommended that 24-h flow-weighted composite samples of the raw wastewater and pond effluents be taken over a 5 week period at the hottest and coldest periods of the year and analysed for BOD, COD, SS, NH₃-N, NO₃-N and total P; faecal coliform numbers should be determined on grab samples, and algal biomass estimated by measuring chlorophyll concentrations in samples of the pond water column. Pond mid-depth mean daily temperatures and pond sludge depths should also be measured, and local meteorological data obtained. The diurnal variation of pond effluent quality and of dissolved oxygen and temperature with depth should be measured at least once during each sampling season. Recommendations are also given for a more simplified estimate of pond performance in areas where the lack of skilled manpower, materials and equipment preclude the complete minimum evaluation procedure.