Town of Slave Lake to use submerged attached growth reactor (SAGR) to achieve regulatory compliance

The Town of Slave Lake is unlikely to meet anticipated new regulatory limits on its aerated lagoon–based wastewater treatment facility, which discharges continuously into Sawridge Creek. As such, the facility requires additional treatment systems to achieve compliance. In 2015, after a review of the municipality’s 10 Year Capital Plan, a water quality effluent study of the existing lagoon system recommended ammonia nitrogen and total phosphorous limits, which were further developed in discussion with Alberta Environment and Parks. Using a 20-year design horizon, the proposed improvements include rehabilitation of the existing aeration cells and the air distribution and delivery systems, as well as the addition of a new submerged attached growth reactor (SAGR) consisting of a fully aerated clean stone bed. Innovative aspect: • There are only a few examples of SAGR systems operating in cold-weather applications in Canada Replicability: • The project can reasonably be replicated in other small communities with similar issues across Canada Environmental benefits: • Expected reduction in carbonaceous oxygen demand (CBOD5) and total suspended solids (TSS) levels by 60%, and an expected increase in treated wastewater by 30% • Replacing existing blowers will reduce energy consumption by 4% Economic benefits: • The expected annual capital and annual operating/maintenance costs savings calculated at $50,000 and $30,000, respectively • The 30% increase in treated wastewater has the potential to increase development, which will likely increase the future tax base and support future local economic growth Social benefit: • Improved effluent quality is important as the effluent discharges into a waterbody that is the source of potable water for many downstream communities (Project description from original funding application)