Addressing Environmental- and Public Health through Urban Water Profiling of Emerging Contaminants in a South African Urban Setting

The study evaluated the mass balance of various contaminants of emerging concern (CEC) from a South African wastewater treatment works (WWTW) and surface waters located upstream and downstream from the point of discharge. A total of 45 CECs, that are grouped into 16 drug classes, were quantified during multiple sampling events that spanned over a period of two years in the study area. Daily loads (DL; in g/day) of the target analytes in the WWTW showed persistence of various CECs, along with population-normalised daily loads (PNDL; in mg/day/1000inh) of pharmaceuticals and drugs of abuse (DOA) that were estimated for the first time in the study area, using the wastewater-based epidemiology (WBE) approach. Multiple chemical markers were recorded in river water located upstream of the WWTW discharge, suggesting other urban pollution sources that contribute towards the CEC loading in the surface water environment. Environmental risk characterisation for the WWTW effluent and surface waters was done to calculate multiple risk quotients (RQs) for each CEC spanning over various sentinel trophic levels. High risk profiles (RQ>1.0) with a frequency of exceedance (FoE) larger than 75% were recorded for several CECs in both WWTW effluent and surface water locations that warrants the need for more refined surveillance of pollution hotspots in the urban catchment. These findings highlight the need for developing an urban water profiling (UWP) approach similar to conventional WBE approaches, at least for low- and middle-income countries (LMICs) where some (peri)urban communities are not connected to municipal sewage infrastructure and thus lead to direct discharge of human waste products into the natural environment.