Impact of informal settlements and wastewater treatment plants on helminth egg contamination of urban rivers and risks a
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Impact of informal settlements and wastewater treatment plants on helminth egg contamination of urban rivers and risks associated with exposure Isaac Dennis Amoah & Sheena Kumari & Poovendhree Reddy & Thor Axel Stenström & Faizal Bux
Received: 19 March 2020 / Accepted: 5 October 2020 # The Author(s) 2020
Abstract The quality of surface water could be influenced by both anthropogenic and natural factors. This study was designed to determine the impact of informal settlement and wastewater treatment plants on helminth egg contamination of urban rivers and the risks associated with everyday use. We also ascertained the accumulation of these eggs in the river sediments. The study was carried out in two rivers in the eThekwini Municipality of South Africa. Grab samples were taken at different points over a 10-month period. Ascaris spp., hookworm, Toxocara spp., Trichuris spp. and Taenia spp. were the helminth eggs detected in both the water column and sediments, with mean Ascaris spp. eggs of 0–6.3 (± 5.1)/L in the water and 0–6.8 (± 5.2)/kg in sediment samples. The helminth egg concentrations showed seasonal variation, probably due to changes in infection levels of the populations or natural factors, such as rainfall. The informal settlements had a greater impact than treated wastewater. For every 10,000 recreational users of the rivers 19 to 58 may be infected under undisturbed conditions, increasing to 29–88 individuals when the riverbed is disturbed. The risk from agricultural use of the rivers was above the tolerable risk values applicable for wastewater reuse, rec-
I. D. Amoah (*) : S. Kumari : T. A. Stenström : F. Bux Institute for Water and Wastewater Technology, Durban University of Technology, Durban 4000, South Africa e-mail: [email protected] P. Reddy Department of Community Health Studies, Faculty of Health Sciences, Durban University of Technology, Durban 4000, South Africa
ommended by the World Health Organization. This calls for a re-evaluation of the policies governing surface water quality assessment, where the inclusion of helminth eggs and sediment monitoring will be critical. Keywords Helminths . Surface water . Wastewater treatment . Informal settlements . Irrigation . Risk assessment
Introduction Surface water quality is an important factor affecting not only human health but the entire ecological system (Wang et al. 2013). This is most important in urban areas where rivers are impacted by several anthropogenic and natural factors. For example, anthropogenic activities such as industrial, agricultural and chemical spills and dam construction are major contributors to the quality of surface water (Qadir et al. 2008). These are cumulative in nature over time and space (Gazzaz et al. 2012a). Additionally, natural processes such as erosion and climatic conditions may also affect surface water quality (Zhang et al. 2010). River quality is not only an indication of the health of the river but may also reflect the health of the surrounding landscapes (Zhou et al. 2012). Pollution from other sources s
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