FATE OF COLIFORMS AND COLIPHAGES IN THE SEQUENCING BATCH REACTOR (SBR)

Performance of the SBR in terms of commonly used physical, chemical an d biological parameters has confirmed it to be a viable wastewater tre atment option. This study further investigates the use of total colifo rms, fecal coliforms and coliphages to evaluate the removal of selecte d microbiological indicators of potential pathogens by the SBR. Result s from a pilot-scale SBR which received clarified sewage from a local treatment works treating a combined (domestic and industrial) sewage s howed that increases in REA CT time led to increases in the overall re moval of the selected microorganisms. On average, up to 96% of total c oliform and fecal coliform removals and up to 90% of coliphage removal was possible with the SBR operated with 2.5 h of REACT. During FILL, a long FILL (3 h) resulted in reduction of coliforms while there was g enerally only a small reduction of coliphages. During REACT, a short R EACT resulted in increase in selected microorganisms and the increase in coliphage numbers was sequential to that of coliforms. The SETTLE p eriod was found to be crucial An effective SETTLE could be achieved by operating the SBR with a REA CT time of 2-2.5 h.