Comparison of two treatments for the removal of selected organic micropollutants and bulk organic matter: conventional activated sludge followed by ultrafiltration versus membrane bioreactor

Abstract

The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8-10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin - at an MLSS of 6-9 g/L - showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.

Performance of a novel osmotic membrane bioreactor (OMBR) system: Flux stability and removal of trace organics

“…Recent developments in water science and technology have established membrane bioreactor (MBR) systems as a potential alternative to conventional activated sludge (CAS) treatment processes (Guo et al, 2008;Sahar et al, 2011). In comparison to CAS, MBR is more robust with a much smaller physical footprint and improved effluent quality (Judd, 2008).…”

Removal of emerging trace organic contaminants by MBR-based hybrid treatment processes

“…Recent evidence points to adverse impacts of TrOC even at such low concentrations on aquatic organisms and potentially on human health (Schwarzenbach et al, 2010). The conventional activated sludge (CAS) wastewater treatment process may not be adequate for the effective removal of many TrOC (Paxéus, 2004, Sahar et al, 2011. Thus, in recent years, there have been a number of dedicated investigations on advanced treatment processes or their combinations to prevent the release of TrOC into the aquatic environment via effluent discharge.…”

Trace Contaminants: Implications for Water Quality Sustainability

“…The processes employed as secondary wastewater treatment include aerated conventional activated sludge (CAS) systems, or membrane bioreactors (MBRs), as a potential alternative (LeClech et al, 2006;Sahar et al, 2011). The processes employed as secondary wastewater treatment include aerated conventional activated sludge (CAS) systems, or membrane bioreactors (MBRs), as a potential alternative (LeClech et al, 2006;Sahar et al, 2011).…”