New combined system of biological process and intermittent ozonation for advanced wastewater treatment

A new system combining both biological treatment and intermittent ozonation has been developed to reduce excess sludge production with a small amount of ozone. In this system, activated sludge in the aeration tank was circulated via intermittent ozonation. Experimental results have shown that 50% of the sludge generation was cut down with only 30% of the ozone dose required for continuous ozonation. Furthermore, the process had a remarkable effect on maintaining the sludge settling characteristics. The sludge ozonation was almost of little influence on the effluent quality though the slight degradation of effluent quality was observed in few cases. These facts suggested the effectiveness of the newly proposed system for saving costs and stabilizing treatment performance of biological waste water treatment processes. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.