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Coleraine, MN WWTP
Project: Coleraine, MN WWTP
Owner: Joint Wastewater Council, Coleraine/Bovey
Engineer: S E H – Brainerd
Material: 12-14% dewatered sludge, 65 lb/ft3
Processing Rate: 3260 lb/hr (wet)
Lime Feed: 521 lb/hr (16% of wet sludge cake mass)
Pump Flow rate: 7.3 GPM
Reactor Vessel: 36” diameter x 9’ long; 60 minutes detention
The “Standard” process uses the Time / Temp equation of the 503 regulations and we operate at 70C for 30 minutes. The PEC (Pathogen Equivalency Committee) is an operating condition we are working towards. As the ammonia released in the reactor actually kills the pathogens before the temperature does, we are working with the PEC at the EPA to get the Bioset process approved to operate at 55C for 30 minutes. The completed report will be submitted to EPA early this year and hopefully by year’s end anyone who operates a Bioset system will be able to run at 55C rather than 70C. That is a roughly 20% reduction in the already low operating costs – in other words, a big deal.
