Process Evaluation and Selection for the 500 MLD Woodward Ave. WWTP Membrane Facility

The City of Hamilton, Ontario 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 initiated an ambitious program to identify alternative upgrade options for the Woodward Avenue WWTP. Two alternative treatment strategies were short-listed for further study. The first option, termed Parallel MBR / MF, included a more conventional style membrane facility with a MBR facility treating approximately half of the primary effluent in parallel with a membrane filtration facility filtering nitrified secondary effluent from the existing secondary treatment plant. The second option, termed Tertiary Nitrifying MBR or TMBR, involves installing a membrane bioreactor using feed consisting of non-nitrified secondary effluent from existing high rate secondary treatment plants. A detailed triple bottom line (Economic, Social, and Environmental) evaluation was carried out on the two alternatives. The evaluation revealed that the two options are very similar in most respects, with the exception of energy efficiency. More specifically, the T-MBR option was found to require significantly lower energy, primarily due to reduced oxygen demand and more efficient oxygen transfer characteristics within the MBR processes. Annual savings with T-MBR are expected to be 500K. In addition, the additional biogas production with T-MBR is expected to result in additional revenues approaching $600K annually. These factors drove the selection of the T-MBR strategy as the preferred alternative for the expansion of the Woodward Ave. WWTP.