R. G. Qualls, M. P. Flynn and J. D. Johnson, “The Role of Suspended Particles in Ultraviolet Disinfection,” Water Pollution Control, Vol. 55, No. 10, 1983, pp. 1280-1285.
ABSTRACT: Limited water availability coupled with the lack of hygienic and reliable water sources plague rural areas throughout the developing world. Tanzaniahas abundant fresh water sources, yet delivery, disinfection, and conservation outside of large towns is lacking or minimal at best. Here we examine drinking water sources in two climatologically distinct regions in Tanzania. We consider their chemical and microbiological characteristics specifically with respect to the potential for ultraviolet (UV) disinfection treatment. Interviews with local villagers provided information on collection means, frequency, storage, and incidences of water related illnesses. Total suspended solids, iron (Fe) and manganese (Mn) concentrations, total bacterial abundances, presence of fecal coliforms, and evidence of Escherichia coli contamination were measured in 31 water sources. Total suspended solids exceeded 15 mg/L, the limit for effective UV treatment, in more than half the sources. Principal component analysis indicated a positive correlation of bacterial abundances with levels of Fe. Water with elevated levels of Mn was associated with greater incidences of diseases. Levels of both Fe and Mn appeared to be more dependent on water source than on climatic differences with the chemical composition of the source rock and redox conditions of the water source at time of collection likely contributing to measured concentrations. E. coli was detected more frequently in water sources in the drier Kondoa district than in the wetter Arusha region. Water quality and socio-economic conditions within villages were linked to incidences of water-borne diseases. The maximum risk of exposure to diarrhea-causing pathogens, for example was strongly related to household income level. Nonetheless, incidences of diarrhea were reduced by more than 40% when the average monthly household expenses increased from US $10 to $20. Finally, to the best of our knowledge, this is the first study known to derive an empirical relationship between water-related diseases and poverty.