Evaluation of a membrane bioreactor system as post-treatment in waste water treatment for better removal of micropollutants

• Published in: Water research (Oxford) 2016-12, Vol.107, p.37-46
• Main Authors: Arriaga, Sonia, de Jonge, Nadieh, Nielsen, Marc Lund, Andersen, Henrik Rasmus, Borregaard, Vibeke, Jewel, Kevin, Ternes, Thomas A., Nielsen, Jeppe Lund
• Format: Article
• Language: English
• Subjects: Bioreactors; Degradation; Emerging organic; Hydrogenophaga; Ibuprofen; Membrane reactor; Membranes; Microorganisms; Micropollutants; Naproxen; Nitrospira; Polishing; Polishing step; Waste Disposal, Fluid; Waste Water; Wastewater treatment; Water; Water Pollutants, Chemical; Water Purification
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2016.10.046

Organic micropollutants (OMPs) such as pharmaceuticals are persistent pollutants that are only partially degraded in waste water treatment plants (WWTPs). In this study, a membrane bioreactor (MBR) system was used as a polishing step on a full-scale WWTP, and its ability to remove micropollutants was examined together with the development and stability of the microbial community. Two stages of operation were studied during a period of 9 months, one with (S1) and one without (S2) the addition of exogenous OMPs. Ibuprofen and naproxen had the highest degradation rates with values of 248 μg/gVSS·h and 71 μg/gVSS·h, whereas diclofenac was a more persistent OMP (7.28 μg/gVSS·h). Mineralization of 14C-labeled OMPs in batch kinetic experiments indicates that higher removal rates (∼0.8 ng/mgTSS·h) with a short lag phase can be obtained when artificial addition of organic micropollutants was performed. Similar microbial populations dominated S1 and S2, despite the independent operations. Hydrogenophaga, Nitrospira, p55-a5, the actinobacterial Tetrasphaera, Propionicimonas, Fodinicola, and Candidatus Microthrix were the most abundant groups in the polishing MBR. Finally, potential microbial candidates for ibuprofen and naproxen degradation are proposed. •Polishing of WWTP effluent by MBR can efficiently remove micropollutants.•Biomass actively removing pollutants can be accelerated by amendment of exogenous pollutants.•Microbial community structure development reveals removal candidate organisms.•Polishing by MBR efficiently removes COD under stable operation at full scale WWTP.