Deoxygenation andReaeration Coupled hybridMixing cells Based Pollutant Transport Model to Assess water Quality Status of a River

Abstract

Prediction of spatial and temporal variation of water quality is vital for managing pollutants<br />disposal into the rivers. Depletion of dissolved oxygen (DO) takes place due to the consumption of oxygen by<br />microbes to digest bio-degradable pollutants which enter a water course. Reaeration takes place in a specific<br />rate depending on DO deficit. Many investigators have formulated models as an alternative to the Fickian<br />Model for the advection dispersion pollutant transport. Since Streeter-Phelps research on BOD-DO modeling,<br />many researchers have studied fate of pollutant considering first order reaction along with only advection. The<br />Streeter-Phelps dispersion model includes deoxygenation and reaeration along with advection and dispersion<br />and which has been solved by defining an axillary variable relating DO deficit and BOD concentration. Thus<br />this paper considered first order decay and reaeration along with advection and dispersion to simulate spatial<br />and temporal variation of DO concentration using a hybrid mixing cells model. The proposed model has been<br />successfully applied for a hypothetical flow conditions and the River Brahmani, India. River flow requirement<br />and regulation for pollutant disposal with pre-treatment were optimized using the responses of proposed<br />model for this River. This research analyzed the selected river reach using proposed model having a particular<br />flow and channel characteristics and found that release of 1180m3/s from Rengali Dam is required to avoid<br />pollution problem. However, in absence of this flow at least 50% of pretreatment pollutants are required<br />before released into river Tikira.