Fixed biomass process and its resistance to elevated copper loads during carbon removal and nitrification of industrial wastewater.

Metal compounds such as copper are known to be inhibitory or toxic to biological activity within wastewater treatments when reaching a certain threshold concentration. Little information on threshold values can be found for biofilm process like Biological Aerated Filters (BAFs). In this study, a BAF pilot plant (Biostyr®) for carbon removal and nitrification was operated to study its response to copper concentration variations. Biological activity was maintained at copper concentration higher than the stated thresholds for heterotrophic and autotrophic biomass in activated sludge systems. Carbon removal was not affected at copper concentrations around 20 mg/l. Autotrophic biomass growth was inhibited at a concentration above 2.5 mg Cu/l.