As urban and industrial development increases, the quantity of waste generated also increases. These wastes pose a serious threat to public health when they are not readily disposed off. When these wastes are removed by water carriage system, they are termed wastewater. Wastewater is the used water or liquid waste of a community, which includes human and household waste together with street washings. Industrial waste and such ground and storm water may be mixed with it. The use of domestic wastewater for irrigation is advantageous for many reasons including water conservation, ease of disposal, nutrient utilization, and avoidance of surface water pollution. Nevertheless, it must be borne in mind that although the soil is an excellent adsorbent for most soluble pollutants, domestic wastewater must be treated before it can be used for crop irrigation to prevent the risk to both public and the environment.
This study aimed at designing and constructing a model waste stabilization pond and final contact filtration unit, for the treatment of influent domestic wastewater for environmentally friendlier discharge.
Overview of Waste Stabilization Ponds
The most appropriate wastewater treatment that could be applied before effluent discharge to a watercourse would be that which produced as effluent meeting the recommended microbiological and chemical quality guidelines both at low cost and with minimal operational and maintenance requirements (Arar 1988). Adopting as low a level of treatment as possible is especially desirable in developing countries, not only from the point of view of cost but also in acknowledgement of the difficulty of operating complex systems reliably. In many locations it would be better to design the reuse system to accept a low-grade of effluent rather than to rely on advanced treatment, which continuously meets a stringent quality standard. Waste stabilization ponds (WSP) are now regarded as the method of first choice for treatment of wastewater in many parts of the world. In Europe, for example, WSP are very widely used for small rural communities (up to populations of about 2000, but large systems exist in Mediterranean France, and also in Spain and Portugal) (Bucksteeg 1987). However, in warmer climates (the Middle East, Africa, Asia and Latin America) ponds are commonly used for large populations (up to 1 million). In developing countries like Nigeria, and especially in the tropical and equatorial regions, wastewater treatment by WSP’s has been considered an ideal way of using natural processes to improve wastewater effluents. In natural treatment systems such as WSP, the pathogens are progressively removed along the pond series with the highest removal efficiency taking place in the maturation ponds (Mara etal. 1998).