The Abydoz Wastewater Treatment Facility in Stephenville, Newfoundland was commissioned in 2009-2010. It consists of 5 acres of HDPE lined containment cells used for containment of the wastewater. It is the largest subsurface engineered wetland system providing secondary treatment in Canada.
Located on the Stephenville airport property, the subsurface flow ensures that the wetland does not attract water fowl or other wildlife that could impact the airport operations.
Design
Population: 7,800 PE (Population Equivalent)
Average Flow: 4,555 m3/day
Wetland Treatment Area: 20,000 CY
Average Effluent Results
CBOD: <10 mg/L
TSS: <10 mg/L
Process
Effluent from the town passes through a spiral screen to remove plastics and non-biodegradable items. Then the flow enters a primary clarifier to settle out suspended solids. From the clarifier the flow is split eight ways and proceeds through the horizontal-flow wetland beds where biological reduction takes place. The flow is then recombined and passes through two vertical beds with final discharge to the ocean.
Sludge treatment cells are located on the other side of the airport. The wetland sludge cells dewater and mineralize the sludge removed in the clarifier, producing a compost-like material. On site sludge treatment cells provide significant cost savings by eliminating expensive sludge transportation and disposal costs.