AWWA WQTC55169

The method of disability adjusted life-years (DALYs) was used to compare positive and negative health effects of drinking water disinfection by ozone at Neuilly-sur-Marne water treatment plant. The reduction of the risk of infection with Cryptosporidium parvum was compared with the risk of renal cell cancer arising from bromate. Different pretreatment and ozonation practices were evaluated: first current or degraded pretreatment efficiency resulting in 2.5 or less log removal of C. parvum. Four ozone doses (from 0 to 4g/m 3 ) were considered at two water temperatures. The impact of improving the hydraulic efficiency of the ozone contractors, and of pH reduction was also evaluated, as the two factors are considered possible means to improve disinfection while limiting bromate formation. It appears that in the case of the Neuilly-sur-Marne treatment plant, the health impact of producing moderate amounts of bromate is outweighed by the health benefits of reducing the risk of cryptosporidiosis. Under current practices, minimal disease burdens were found for ozone doses between 1.5 and 2.5 mg/L. Includes 12 references, table, figures.