ABSTRACT
This research assessed the public health risk of bacteriological water contamination of the Kafubu River in Zambia against the backdrop of limited research on the ambient surface water quality of the river that is flowing in a catchment area characterised by high human activity. Human activity, particularly sewer effluent disposal, is continually loading the river with bacteria that could pose adverse health risks to the public. The study was based on a systematic sampling design by which geo-referenced sampling points were selected at 500 m intervals along the section of the river where the intensity of human activity was very high. Grab water samples were then collected in the months of October and November, 2017 and were analyzed for the bacteriological concentrations of total coliforms, faecal coliforms and Escherichia coli known to have a bearing on public health. Using exploratory data analysis to generate descriptive statistics, followed by single-factor analysis against the threshold for the ambient water quality of rivers, it was found that the bacteriological concentrations of total coliforms (2,497-17, 101cfu/100ml), faecal coliforms (925 - 13,083 cfu/100ml) and Escherichia coli (27 – 4,302 cfu/100ml) indicated that the ambient water quality of the Kafubu River was impaired. Geo-statistical modeling further showed that the bacteriological concentrations were spatially concentrated around the sewer effluent discharge points along the river. This water pollution scenario could then be attributed to ineffective wastewater treatment at the sewerage plants within the river catchment. The study concludes that there is a public health risk of water-borne disease in direct use of raw water from the Kafubu River on account of the significantly high bacteriological water contamination, and it is recommended as such that best management practices for sewer effluent disposal into the river should be enforced, and further research is required to model water pollution at varying time scales across the river continuum.
