Evaluation and Verification of Thermal Stratification Models for Waste Stabilization Ponds

Abstract

Stratification is a usual phenomenon occurring in waste stabilization ponds which needs to be incorporated in prediction models. The occurrence of stratification in waste stabilization pond (WSP) alters the flow pattern of the pond. Hence, its study is important for complete and accurate modeling of the WSP. In this study, two mathematical models developed for prediction of the condition of thermal stratification in WSPs under different hydraulic conditions and flow regimes were compared. Also the pond depth is divided into ‘N’ parallel layers, each of which is considered to possess a different dispersion number and bacterial die-off coefficient. The models are verified with data collected from the full scale waste stabilization pond at Nsukka. Results of field experiments show that the same result under the plug flow and completely mixed flow condition and hence gives reliable comparison. Also the coefficient of correlation ranged from 0.992007322 to 0.939220284 for plug flow model and 0.995915575 to 0.9388977 for completely mixed flow model, showing that the two models produced almost the same results.