Efficient treatment of synthetic wastewater contaminated with emerging pollutants by anaerobic purple phototrophic bacteria

Abstract

This work investigates the biological treatment of synthetic wastewater contaminated with emerging pollutants (EPs) by anaerobic purple phototrophic bacteria (PPB) in a continuous photo-anaerobic membrane bioreactor. The effect of the hydraulic retention time (HRT) on the reactor performance has been analysed. Results indicate that the reactor performance is stable and the PPB can settle inside the reactor. A COD removal efficiency higher than 90% is achieved at a HRT of 24 h. Lowering the HRT to 12 h caused an initial drop of the COD efficiency that was subsequently recovered along the curse of the experiment. Biomass showed a high activity (close to 1 g COD/g COD d) and good settling characteristics when the attached growth was avoided, indicating a good link to downstream processes. Anaerobic digestion of PPB biomass was performed by dedicated BMP tests. Results indicate that lowering the HRT considerably improves the biogenic methane potential, presumably due to accumulation of organic compounds. A further analysis of EPs balances is being carried out and will show the fate of these compounds within the reactor.