The research comparing the action of sodium hypochlorite and peracetic acid to disinfect drinking water with high concentration organic matter was carried out in similar conditions. The dissolved organic carbon (DOC) concentration was from 4.652 to 30.13 mg/L in raw water, from 5.105 to 26.16 mg/L in water disinfected with chlorine and from 15.89 to 32.72 mg/L in water disinfected with peracetic acid. The efficiency of the two disinfectants was evaluated comparing the inactivation of three indicator microorganisms: Escherichia coli ATCC 11229, coliphages and Clostridium perfringens ATCC 13124 previously cultivated and inoculated to the water just before the essay. The Chlorine and peracetic acid concentrations applied was 2.0, 3.0, 4.0 and 5.0 mg/L each of them with contact time of 5, 10, 15 and 20 minutes. When applying 3.0 mg/L of chlorine 3 log inactivation of E. coli with 20 minutes contact time, 2.92 log inactivation of coliphages with 10 minutes contact time and 2 log inactivation of C. perfringens with 15 minutes contact time was obtained. The peracetic acid was effective for the inactivation of all indicator microorganisms even to water with high concentration organic matter. Using peracetic acid dosage of 5 mg/L more than 6 log inactivation of E. coli with 15 minutes contact time, more than 5 log inactivation of coliphages with 20 minutes contact time and more than 4 log inactivation of C. perfringens with 10 minutes contact time was obtained.
Chlorine; C. perfringens; coliphages; E. coli; peracetic acid; water disinfection
