Hydrogen supplementation enhances microbial removal of selected organic micropollutants, reduces associated ecotoxicity, and improves nutrient removal in domestic wastewater effluent
Organic micropollutants (OMPs) compose a group of emerging contaminants that occur in environmental waters at trace concentrations (microgram/L to nanogram/L) with suspected adverse effects on ecosystems and human health. Conventional wastewater treatment plants (WWTPs) are not designed to eliminate the more recalcitrant OMPs. As such, WWTP-effluents are a major source of OMPs in the aquatic environment, and sustainable advanced treatment options are required. One option concerns the biodegradation of OMPs, but several studies show that it might be constrained by the residual low energy content in effluent waters. Since molecular hydrogen (H2) has been identified as a universally available energy source utilised by various bacteria in oligotrophic environments, supporting mixotrophic growth, we examined the hypothesis that H2 can enhance OMP-removal and concomitant ecotoxicity from domestic wastewater effluent. To this end, a lab-scale biological trickling filter supplemented with H2 (1.5% in the aeration with ambient air) was operated in continuous mode for treating a field-collected domestic WWTP-effluent.