Comparison of Sludge Wastage Control Strategies

In order to compare whether sludge age control by wastage from the biological reactor is more efficient than wastage from the final clarifier in wastewater treatment plants by activated sludge, the Benchmark Simulation Model 1 has been modified. The secondary settler has been made reactive and the sludge settling characteristics vary as a function of the amount of gas produced by denitrification. Proportional-integral controllers were implemented with success to control the sludge age by wastage from the biological reactor or the clarifier and were tested under different dynamic situations. It was confirmed that a simple strategy of constant wastage from the biological reactor could be a good alternative when no suspended solids sensor is available.