Dynamic Models for Clarifiers of Activated Sludge Plants with Dry and Wet Weather Flows

Abstract

Dynamic simulation of wastewater treatment plants becomes more realistic, if models of primary and secondary clarification are implemented. A simple model of the primary clarifier can describe dynamics of buffered influent or sludge water concentrations. Different changes in ratios of particulate fractions of COD depending on influent flows are modelled as well. Processes in activated sludge plants are affected by the replacement of sludge to the clarifier and by the loss of solids through the effluent. These effects are very strong at combined water flows. The two models best applicable as of yet did not meet measured values for effluent solids. One of them describes thickening and storage of sludge quite well. The developed two component model presented here is able to represent the behaviour of secondary clarifiers at dry and wet weather flows.