Annacis Island

Project Updates

Annacis Island Wastewater Treatment Plant Co-digestion Facility

Operated by Metro Vancouver, the Annacis Island Wastewater Treatment Plant - AIWWTP, is the largest secondary treatment plant in British Columbia and serves approximately 1,000,000 people. The AIWWTP processes sewage flows of approximately 580,000 m3/d (131 MGD), and the treated effluent is discharged into the Fraser River. The amount of biosolids produced from the anaerobic thermophilic digesters and dewatering centrifuges is about 33 dry tonnes/day at 30% total solids. The digesters also produced on average 40,000 m3/day of sludge gas that is used by the boilers and co-generation engines at the Plant.

A co-digestion process adds digestible substrates directly into the anaerobic digesters in addition to the normal feed of municipal sludge processed from the liquid stream. It provides a notable benefit of boosting gas production and hence increases the renewable energy and GHG credits for the Plant. The Co-digestion Facility at Annacis is a full scale pilot facility which will allow Metro Vancouver to receive and test a variety of digestible organic wastes, monitor the feed rates and measure the effects of these feedstocks on the performance of the digesters. The facility is also capable of receiving and screening thickened sludge hauled from other wastewater treatment plants, providing relief to manage digester upsets at other sites.

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April 2011