Reduced energy consumption and improved nitrogen removal by using more effective aeration
In this study, an aeration volume control strategy for an activated sludge process is evaluated in a pilot plant at Hammarby Sjöstad in Stockholm, Sweden. The main idea has been to let the DO concentration in some of the aerated compartments be determined by the DO concentration in other compartments. In this way only sensors for measuring the DO concentrations are needed for the decision of time varying DO set-points. The high reliability of such sensors implies robust input values for the proposed control strategy. The suggested manipulations of the DO set-points are indirectly determined by the current load into the plant. Compared to constant DO control, the suggested aeration volume control strategies could reduce the effluent nitrate and ammonium concentrations significantly without increasing the aeration energy. A simulation study including an evaluation of different controller design parameters has also been performed.