| occurrence of gram-negative bacteria in drinking water undergoing softening treatment. | a study was carried out on the presence of gram-negative bacteria in the municipal waters of bologna (italy) undergoing softening using domestic ion exchangers with an automatic disinfection mechanism. the softening process was seen to cause a 15 fold increase in 22 degrees c and 36 degrees c heterotrophic plate counts. there was a 30 fold increase in gram-negative bacteria and their number correlated directly with temperature and inversely with active residual chlorine. organic matter had no ef ... | 1997 | 9636986 |