600 MLD Membrane Bioreactor for Tertiary Nitrification in Hamilton, Ontario
The City of Hamilton is faced with increasing pressure from growth and development, greater wet weather treatment needs, and stringent effluent targets. In order to address these challenges, the City of Hamilton has initiated an ambitious program to identify alternative upgrade options for the Woodward Avenue WWTP. One of the alternatives identified for further investigation is a tertiary nitrifying membrane bioreactor (T-MBR) concept. The concept generally involves installing a membrane bioreactor after the existing secondary clarifiers. The MBR would be operated to allow for full nitrification while also polishing the secondary effluent to meet stringent limits with respect to total phosphorus. The primary advantages of the T-MBR concept compared to the other alternatives included the small footprint requirements (site has limited opportunity for expansion), the opportunity for phased construction to meet changing effluent requirements, the ability to meet very low targets (which may be required), the reduced impact of sludge bulking on performance, and the minimal impact to the existing facility during construction. This paper describes the general treatment concept and some potential alternative treatment schemes, the expected effluent quality, as well as the expected design requirements and operating parameters of the T-MBR. Because the technology is relatively unproven, the City is currently undertaking an extensive 8-month pilot test to prove the treatment concept and provide operational and design information to permit a more detailed evaluation. The pilot testing will also include the testing of tertiary membrane filtration to allow comparison with the T-MBR concept and to gather further information on the use of membranes for other potential upgrade alternatives that are being evaluated as part of an ongoing Wastewater Master Plan.