Effect of Aeration on Residence Time in Biological Wastewater Treatment

Abstract

Aerobic wastewater treatment requires extensive aeration, which primary function is to provide oxygen to the biomass responsible fordegradation of wastewater constituents. Besides the effective oxygen transfer efficiency aeration is responsible for fluid flow created by bubbles. In this research bubbles were released from plate diffusers and the impact on mixing were analyzed. Various aeration flow rates and initial bubble sizes were calculated. Residence time distributions in each scenario were compared applying numerical tracer study. Outcome of the calculations is that the aeration reduces the theoretical residence time significantly and therefore the traditional sizing methods needs to be revisit in wastewater treatment.