This paper describes the strategies used to optimize a cardboard paper factory wastewater treatment plant regarding operational problems caused by the occurrence of foaming and filamentous organisms. The operational modifications involved the use of an equalization tank, the reduction of oil and grease from the industrial process, the addition of sodium hypochlorite at the inlet of the secondary settler to control filamentous organisms and phosphoric acid to correct the nutrients balance and BOD. A correct value of biomass concentration and sludge age were maintained constant all the time. The first results showed that the TSS removal efficiency in the primary settler was higher than 70%, followed by an improved performance of the biological reactor due to the control of filamentous organisms and better performance of the secondary settler.
Process optimization; activated sludge; foaming control; industrial wastewater
