Bromides in treated wastewater: limiting the choice of quaternary wastewater treatment technologies for residual micropollutant removal. An Estonian case study

The recent changes in the European Union Wastewater Directive require micropollutant elimination from the effluents of wastewater treatment plants serving at least 150 000 population equivalents, and in some cases even starting from 10 000. While ozonation can degrade micropollutants without secondary wastes, the treated effluent composition must be considered, specifically the concentration of bromide (Br–). Depending on its amount and oxidant dose, bromide can potentially be oxidised to carcinogenic bromate (BrO3–). This research investigates bromide amounts in the effluents of Estonian wastewater treatment plants serving at least 10 000 population equivalents as preliminary work for quaternary wastewater treatment aimed at micropollutant removal.