The Duffin Creek Biosolids to Energy Experience: One Year On

The Duffin Creek Water Pollution Control Plant (WPCP) is a conventional activated sludge plant located in Pickering, Ontario, Canada. The liquids module of the WPCP has a treatment capacity of 630 MLD (∼166 mgd), following the Stage 3 Liquids Expansion completed in 2010, which increased treatment capacity from 420 MLD (∼110 mgd). The Stage 3 Solids Expansion increased the firm solids processing capacity from 90 t/d DS (99 dtpd) to 270 t/d DS (297 dtpd), has completed commissioning and reliability and performance demonstration was in progress at the time of writing and will be in full operation by the end of 2014. The Duffin Creek WPCP is the largest thermal processing facility with energy recovery (420 t/d DS installed capacity) in North America. The Stage 3 Solids Expansion modified the existing digesters, replaced the dewatering facility and added two fluid bed reactor (FBR) trains, as well as ash thickening and dewatering.Performance testing carried out on both processing trains demonstrated that they met the throughput requirements and the Environmental Compliance Approval (air permit) requirements. Performance of the system is comparable to the SSI MACT regulations for the parameters controlled.Operational issues and lessons learned with the boiler feedwater pumps, the medium pressure steam condenser system and the enhanced mercury removal system (GAC absorber system) are presented. What appear to be minor issues can result in long periods of productivity loss.