The Development of Health Guidelines for Wastewater Reclamation

Wastewater reclamation has multiple benefits including water conservation and supplementing available water resources, while providing valuable nutrients to the soil. It also contributes to the reduction of environmental pollution, by reducing wastewater discharges to surface and underground water sources. However, potential health problems associated with reuse of wastewater must be carefully assessed and health guidelines developed which effectively reduce health risks and allow for the full social and economic benefits of wastewater reuse to be achieved. This paper reviews the major findings of a World Bank/United Nations Development Program study aimed at evaluating health guidelines for wastewater reuse in agricultural irrigation. This study concludes that early guidelines were often unjustifiably conservative and recommends for unrestricted irrigation of all crops including edible vegetable crops, a microbial quality of the effluent of 1000 fecal coliforms/100 ml and l or less helminth eggs/litre. This microbial standard can be achieved in well designed multi-celled stabilization pond systems which are low cost, robust and simple to operate and are particularly suited to developing countries in warm climates. Alternative advanced treatment technologies can also meet these guidelines. The World Health Organization has recently provided a new impetus to wastewater reclamation in agriculture throughout the world with its official approval of these guidelines.