IMPROVEMENT OF A RECIRCULATING PLANT BY INTRODUCING STAR CONTROL

During the last 20 years, control of wastewater treatment plants has d eveloped from very simple to advanced computer control methods based o n on-line measurements. Fortunately, both on-line equipment and comput er system technology are still developing fast and have become applica ble at WWTPs. The use of online measurements for real time control is advantageous at most plants over 15.000 personal equivalent performing biological nutrient removal. Control strategies have demonstrated the ir efficiency at several Scandinavian wastewater treatment plants. Exp erience shows that the applied control strategies are efficient and ro bust for practical implementation, provide savings in energy and chemi cal consumption and decreases the nitrogen content in the effluent. Ex perience from a recirculating BNR plant using the STAR concept for adv anced real time control is described. The on-line nutrient measurement s and excitation of the processes through control strategies have impr oved the process understanding. Control has reduced the consumption of energy by about 30% and eliminated the need for external carbon addit ion, as well as improved the effluent quality of total nitrogen from t he plant The new measurements and data handling methods will make it p ossible to perform dynamic identification of activity in recirculating plants (Nielsen et.al., 1994), and hence give information as to which control strategies improve the biomass activity or favour desired cul tures of micro-organisms.