COMPARATIVE DISINFECTION OF SECONDARY-TREATED SEWAGE WITH CHLORINE DIOXIDE AND BROMINE CHLORIDE

A comparison was made of the inactivation rates of Arcobacter butzleri , coliphages, total coliforms, fecal coliforms, fecal streptococci and heterotrophic plate count in secondary sewage effluent using chlorine dioxide (2 and 4 ppm) and bromine chloride (4 or 8 and 12 ppm) as dis infecting agents. Using these doses the ClO2 gave higher reduction per centages (on average more than 99% at 4 ppm) than those obtained with BrCl. The average values of the fecal indicators are well within the l egal limits. Arcobacter butzleri was more sensitive to the disinfectan ts than other bacteria while fecal streptococci were seen to be more r esistant. From the chemical point of view no differences were seen bet ween the two disinfectants except that the action of ClO2 was stronger regarding BOD5 than that of BrCl. With the exception of dichlorometha ne, the concentration of volatile halogenated compounds showed little variation and values were often lower than detection limits.