EVALUATION OF THE IMPACT OF RETURN FLOWS ON THE OPERATION OF A WASTE-WATER TREATMENT-PLANT

A systemic analysis of a wastewater treatment plant quickly reveals th at return flows from the sludge treatment line affect the water treatm ent process. These return flows have a maximum value that is character istic of a steady state of plant operation and the effects are detecta ble at several levels. It can, for example, influence the operation of the clarifier indicated by changes in the Sludge Volume Index, induce anaerobiosis in the separation works that stems from excess sludge pr oduction or decrease the dewatering of sludges. All these observations lead to the conclusion that the sludge treatment line should be desig ned that it could take up production overloads. It was also found that it is indispensible to monitor the water treatment line operation ste p by step in order to detect rapidly any drift of the operating parame ters from their normal values.