Dynamic Prediction of Wastewater Aeration Basin Temperature

Abstract

A dynamic model was developed to predict activated-sludge aeration basin temperature. The model accounts for hourly or more frequent changes in weather conditions and input parameters such as wastewater temperature, aeration, and biological reaction. The model was verified using data from full-scale treatment plants located across the United States. The various heat transfer terms are evaluated, and the relative contribution from each is shown. Evaporation from aeration can be a major component. Surface aerators cool the basin much more than diffused aeration systems. Diffused aeration systems are preferred for cold climates. The heat of biological reaction is small, except for very high rate processes. The effect of changing weather conditions, such as a cold front, can be predicted. Local relative humidity has a major impact on cooling. The impact of design changes, such as covering an aeration basin, insulating walls, or changing retention times, can be determined using the developed model.