NUTRIENT REMOVAL - ONLINE MEASUREMENTS AND CONTROL STRATEGIES

New control strategy principles with respect to nitrogen and phosphoru s removal in activated sludge plants are described. The principles inc lude control of phase length and oxygen set point based on criteria fu nctions and continuous on-line measurements of ammonium, nitrate, phos phate and pH. Five case studies are stated which describe improvements in biological nitrogen and phosphorus removal and in chemical phospho rus removal at activated sludge plants ranging from 5000 to 220000 pop ulation equivalents (0.25 to 11 MGD). The improvements due to the new strategies are basically a reduction of nutrients in the effluent and a reduction in the amount of chemicals and electricity consumed.