Properly and Easily Baffled

Activated sludge processes that use bioselection and provide treatment for nutrient removal, such as biological phosphorus removal or biological nitrogen removal, require discrete stages or zones for optimum results. For example, biological phosphorus removal operates best under anaerobic conditions (no dissolved oxygen or nitrates), while nitrification requires dissolved oxygen (DO) and denitrification occurs most efficiently without DO and with the recycle of nitrates. Thus, each process has specific environmental conditions that produce the most efficient treatment and avoid back-mixing zones.