Investigation of Membrane Bioreactor Effluent Water Quality and Technology
Year Released: 2012
Type: Scientific Investigation
Funding Partners: Bureau of Reclamation, Veolia Water Russia (Anjou Recherche), STOWA (Foundation for Applied Water Research in the Netherlands), Singapore PUB
Total Investment: $353,315.58 (Cash: $199,999.99, In-Kind: $153,315.50)
Principal Investigator: Joan A. Oppenheimer, MWH
Membrane Bioreactor (MBR) technology has become well established worldwide over the last decade as an activated sludge process option for advanced treatment and recycling of municipal and industrial wastewater. The MBR process utilizes low-pressure membrane filters that are submerged within or adjacent to the conventional activated sludge (CAS) reactor, which eliminates the need for a secondary clarifier or tertiary filters. Although the effluent water quality of MBR processes has been reported to be superior to that of CAS systems, largely attributed to the membrane barrier, the water quality performance of pilot- and full-scale MBR processes indicate varying degrees of performance with respect to microbes, nutrients, aggregate organics, trace organic compounds, and trace metals.
Goals and Objectives
The project synthesizes a dispersed body of research on the application of MBR technology for municipal wastewater treatment available from literature reviews, case studies, bench and pilot-scale testing, system comparisons, and full-scale demonstrations, and supplements it with effluent quality data predictions obtained from operation scenarios with an MBR model developed as part of the study.
The project included these tasks:
- Comprehensive analysis of MBR effluent quality and operational data collected from a wide variety of sources that included peer-reviewed and grey literature of pilot studies and full-scale plant operations;
- Comprehensive analysis of data obtained through surveys of vendor suppliers and operating full-scale installations; and
- Synthesis of data obtained for aggregate organics and trace organic compounds with the predictions of a mechanistic MBR model developed to simulate different operating scenarios.
Findings and Conclusions
MBR installations above 1 MGD have increased 300% in the last five years. Overall aggregate organic removal is similar to conventional activated sludge (CAS) processes, but biologically degradable or assimilable organic carbon (BDOC and AOC) content is lower due to the membrane’s retention of some portion of the biomass associated products (BAP). Removal of nutrients, trace metals, and trace organics is similar in MBR and CAS systems, but the MBR will have better removal performance when these compounds are associated with particles either naturally or through use of chemical precipitation.