ABSTRACT
The management of wastewater should aim at pollution prevention first, followed by pollution control aimed at resource recovery and reuse. This approach offers great potential to enhance water availability and to protect water resources from pollution. This Chapter deals with wastewater management in Harare, the capital city of Zimbabwe, which is located upstream in the Lake Chivero catchment area. The Chapter aimed at developing a sustainable system for managing water and nutrients (nitrogen and phosphorus) with particular emphasis on wastewater. Data from previous studies and findings from a water quality monitoring study of June 2000 - December 2001 were used. A so-called "3-Step Strategic Approach" to urban (waste)water management was used as a basis for formulating solutions. Under each of the three steps, short-term, medium-term, and long-term solutions were considered. The short-term solutions include reduction of wastewater volume through cleaner production approaches and process re-engineering in industries, with the overall objectives of enhancing water availability and controlling pollution. The medium-term solutions involve treating wastewater to high standards, introducing or improving resource recovery and reuse options, and controlling upstream point and non-point sources of pollution. A long-term solution was suggested based on pollution prevention and direct reuse, treatment at onsite and decentralised levels followed by reuse, and minimal disposal of remaining effluents combined with the stimulation of the self-purification capacity of the receiving rivers. Short-term measures would reduce wastewater flows by 24% and TP by 5%. It is predicted, through modelling, that respective lake TN and TP would be reduced to 0.4 mg/I and 0.0?mg/1 via mea£ures proposed for the medium-term. The long-term measures would aim at sustaining this lake water quality under increased urbanisation conditions. It was concluded that it is feasible to reduce pollution levels in the catchment by applying these phased developments.
