Contaminants of Emerging Concern in African Wastewater Effluents: Occurrence, Impact and Removal Technologies

Abstract

Worldwide, the pollution of water bodies by contaminants of emerging concern (CECs) such as pharmaceuticals, endocrine disrupting compounds, flame retardants including brominated flame retardants (BFRs) and perfluorochemicals (PFCs), micro plastics, nanomaterials, and algal toxins, to name just a few, is creating a new set of challenges to the conventional wastewater treatment facilities, which demonstrate inefficiency in removing/degrading many CECs. As a consequence, environmentalists started to detect the presence of some of those contaminants at alarming levels in certain countries, with possible negative effects on aquatic species and often increased potential for human health risks through the exposure to the contaminated waters, or the reuse of treated wastewater in agriculture and household use. Such issues are more accentuated in the African continent due to various socio-economic problems giving rise to poor sanitation systems and serious shortages in wastewater treatment plants in many regions, making it difficult to tackle the problem of conventional pollutants, let alone to deal with the more challenging CECs. Thus, in order to effectively deal with this emerging environmental threat, African researchers are working to develop and optimize sound sampling and analytical procedures, risk assessment models, and efficient remediation technologies. In this review, related recent research efforts conducted in African universities and research institutions will be presented and discussed with respect to the occurrence and assessment of CECs in African wastewater effluents, the potential risks to aquatic ecosystems and humans, the tailored remediation techniques, along with some knowledge gaps and new research directions.