Primary Sludge Fermenters in BNR Plants: Are they Cost-Effective for Meeting Effluent Phosphorus Limits?

The 100 ML/d Pine Creek WWTP is a state-of-the-art BNR facility that serves the City of Calgary, Alberta. A delay in the construction of the primary sludge fermenters allowed a comparison of the performance of the BNR process with and without fermentation for extended periods of time, and facilitated a life-cycle cost analysis in which the cost of primary sludge fermentation was compared with alternative forms of primary sludge thickening and meeting the effluent total P limit by chemical addition. Data from the first 20 months of plant operation indicated that, with primary sludge fermentation, the plant is capable of reliably meeting its stringent effluent total P target of