Economic Benefits of Advanced Control Strategies in Biological Nutrient Removal Systems

Advances in on-line monitoring of nutrient salt concentrations and computer technology has created a large potential for the implementation of advanced and complex control strategies in biological nutrient removal systems. The majority of wastewater treatment plants today are operated with very little regards to the variations in load and biomass activity.

However, these dynamics can be evaluated on-line using grey box models to describe the most important features of the hydraulic and biological processes. Simulation studies of plants with an alternating process have shown that control strategies incorporating information from the grey box models are capable of reducing the total nitrogen discharge as well as energy costs.

These results have a major impact on both existing and future plants. In fact, it is expected that future plants can be reduced with 10-20 per cent in size, and that the complexity in reactor design of biological nutrient removal systems will be substituted by complexity in control in the future.