Efficiency of Wastewater Treatment System and Its Use for Irrigation - A Case Study of a private University in Ghana

Abstract

The reuse or utilization of treated wastewater for irrigation is conventionally considered as a means of mitigating water shortage or abating water pollution. Wastewater treatment plants designed for reuse in irrigation are more appropriate for developing countries striving to enhance access to improved sanitation. It is well known that successive stages of treatment of sewage effluent reduces the quantity of suspended solids, organic matter and nutrient load, bacteria population as well as biological oxygen demand to the extent that the final treated effluent contains virtually a small fraction compared to the influent sewage. A short-term assessment of the decentralised reuse-oriented effluent system of a private University (in Ghana) was carried out to determine its effluent quality for the purpose of irrigating its landscape. The investigation showed that Total Coliform, E. coli and Vibrio spp. were significantly reduced, through the treatment stages, but not to within Internationally accepted guideline values. Salmonella spp. was not significantly reduced. Physical parameters, nutrients as well as biological oxygen demand did not show any variation along the treatment stages. Suspended solids, optimum temperature and pH were identified as contributing to treatment inefficiency of the plant. It is therefore recommended the treated wastewater, prior to disinfection, should be filtered to reduce suspended solids. This will enhance effective chlorination and by extension, significantly reduce bacteria population. Furthermore Regular monitoring and laboratory analysis of the recycled effluent from the plant should be carried out by the EPA or other professional organisation to ensure compliance.

Keywords: Reuse, Wastewater, Irrigation, Chlorination