[Comparison of the effects of chlorine dioxide, sodium hypochlorite and their combination on simulative water disinfection].
OBJECTIVE
To compare the effects of disinfection of chlorine dioxide (ClO2), sodium hypochlorite(NaClO) and their combination (ClO + NaClO) on simulative water samples.


METHODS
The simulative water samples containing 5.0 x 10(4) - 5.0 x 10(5) cfu/100ml Escherichia coli were prepared in laboratory and disinfected by different doses of chlorine dioxide, sodium hypochlorite and their combination for 60, 60, 30 + 60 min respectively. The kill ratio for Escherichia coli, and the residual chlorine dioxide, and the product of chlorite ion (ClO2-) and total residual chlorine were detected and compared by the membrane filter(MF) technique and electrometric titration.


RESULTS
The minimum effective dosage (MED) for disinfect of simulative water samples were 0.4 mg/L of chlorine dioxide, 0.5 mg/L of sodium hypochlorite, and the 0.1 mg/L + 0.3 mg/L or 0.2 mg/L + 0.2 mg/L of their combination. By comparision with disinfection of ClO2 and NaClO alone, the residual chlorine dioxide increased 13.43% - 166.67% in simulative water sample under disinfection by the combination of ClO2 + NaClO, While chlorite ion decreased 13.11% - 19.97% and total residual chlorine increased 9.34% - 40.15%.


CONCLUSIONS
The combination of chlorine dioxide and sodium hypochlorite for disinfection of drinking water could achieve better effect of disinfection and decrease disinfection by-products as well.
Wang
Ying
Y
Institute of Environmental Medicine, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, MOE Key Lab of Environmental Health, Wuhan 430030, China. happywy1980@163.com
Li
Na
N
Lu
Yi
Y
Wang
Yazhou
Y
D017606:Chlorine Compounds / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects*; D010087:Oxides / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide; D012973:Sodium Hypochlorite