Effect of point-of-use disinfection, flocculation and combined flocculation–disinfection on drinking water quality in western Kenya*


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    Presented in part at the International Water Association Health-Related Water Microbiology Symposium, Cape Town, South Africa, Abstract 96, 14–19 September 2003.

John A. Crump, Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, MS A-38, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA (e-mail: jcrump@cdc.gov).


Aims:  Point-of-use drinking water disinfection with sodium hypochlorite has been shown to improve water quality and reduce diarrhoeal disease. However, the chlorine demand of highly turbid water may render sodium hypochlorite less effective.

Methods and Results:  We evaluated a novel combined flocculant-disinfectant point-of-use water treatment product and compared its effect on drinking water quality with existing technologies in western Kenya. In water from 30 sources, combined flocculant-disinfectant reduced Escherichia coli concentrations to <1 CFU100 ml−1 for 29 (97%) and reduced turbidity to <5 nephelometric turbidity units (NTU) for 26 (87%). By contrast, water from 30 sources treated with sodium hypochlorite reduced E. coli concentrations to <1 CFU 100 ml−1 for 25 (83%) and turbidity to <5 NTU for 5 (17%).

Conclusions:  For source waters over a range of turbidities in western Kenya, combined flocculant-disinfectant product effectively reduces turbidity to <5 NTU and reduces E. coli concentrations to <1 CFU 100 ml−1.

Significance and Impact of the Study:  The novel flocculant-disinfectant product may be acceptable to consumers and may be effective in reducing diarrhoeal disease in settings where source water is highly turbid.