Improvement of River Water Quality Through a Seasonal Effluent Discharge Program (SEDP)

Abstract

In an attempt to improve water quality in rivers and streams or to maintain water quality without further degradation, most Environmental Protection Authorities throughout the world set stringent effluent discharge limits on sewage treatment plants. In most cases, these limits are based on Best Available Technology. The use of this technology is expensive, and does not consider the ability of the flow condition of receiving waters in digesting wastewater. An alternative strategy called ‘seasonal effluent discharge program’ (SEDP) was investigated in this study, which utilises different flow conditions in the river, in different periods in order to accommodate various wastewater discharge concentrations. A river water quality model was developed for Yarra River in Victoria (Australia). A genetic algorithm optimisation procedure was used for estimating the reaction parameters and calibrating the model. The river water quality model was then used to study the effectiveness of SEDP. The results of the study revealed that the SEDP is a feasible strategy for improving water quality in Yarra River, since the river has high assimilative capacity in winter compared to summer. This allows a lower wastewater treatment (via a lower chemical dosage) during winter, because of the high dilution capacity in the river.