NOVEL HIGH-RATE PROCESSES FOR SEWER OVERFLOW TREATMENT

There is a demonstrated need for high-rate processes, for the treatmen t of storm induced sewer overflows, that are capable of removing parti culate solids down to at least 10 microns in size. Chemical coagulatio n processes are capable of producing a high quality treated sewage eff luent that would be suitable for discharge to a receiving water such a s a separate stormwater system. Compact, high-rate methods of solids s eparation within these processes will make them more attractive for us e in areas where land is expensive or unavailable for large storage ba sins or settling tanks. Two approaches that are being developed at the CSIRO, Division of Chemicals and Polymers, appear to fulfil this requ irement; these are magnetite assisted sedimentation and a high-rate fi ltration process. Both approaches combine the advantages of chemical c oagulation with a high-rate separation of the flocculated solids and a re discussed in this paper. Copyright (C) 1996 IAWQ. Published by Else vier Science Ltd.