Study on inactivation of iron bacteria isolated from real drinking water distribution systems by free chlorine and chloramine

To study the inactivation characteristic of iron bacteria isolated from real drinking water distribution systems and investigate the influence of disinfectants, pH and temperature on inactivation process. Two kinds of iron bacteria were isolated from the water phase in distribution systems and identified as Acinetobacter baumannii and Microbacterium oxydans . Bench-scale study on inactivation of the two kinds of iron bacteria were carried out, with the impact of disinfectants, pH and temperature under different levels concerned. Free chlorine and monochloramine could achieve an inactivation rate of 99.9% on both A. Baumannii and M. Oxydans with the CT-value of 10 mg/L·min. Free chlorine was more effective than monochloramine with 1∼2 log higher inactivation rate. Microbacterium oxydans was more resistant to disinfectant than A. Baumannii . High pH enhanced the inactivation of A. baumannii and low temperature availed the inactivation of both A. Baumannii and Microbacterium . For iron bacteria in the water, inactivation ratio could not reach 99% when residual chlorine was 0.05 mg/L in drinking water distribution systems according to Standards for Drinking Water Quality.