Comment

Activated Sludge System Design

Response

The step-wise approach excerpted by the reviewer from textbooks on activated sludge and aerobic digestion design are an out-dated, overly simplistic approach to activated sludge, nutrient removal and aerobic digestion process design. Process models have been developed over the last 30 years specifically to better capture the complexity and number of biological, physical and chemical interactions occuring in activated sludge and aerobic digestion systems. The Biowin model is routinely calibrated against data collected from hundreds of treatment plants worldwide. A more comprehensive listing of parameters used in the Biowin process model can be added to the Final Draft Report, but Biowin’s parameters are also available online.