AWWA ACE61823

City of Wetaskiwin (Alberta, Canada, population 11,200) obtains its water supply from Coal Lake, a hyper-eutrophic water body. Coal Lake contains high levels of microcystin, a harmful toxin released by cyanobacteria (0.07 to 14.8 µg/L) and high dissolved organic levels (as high as 49 mg/L). The treatment plant is continuously challenged by zooplankton, especially Copepod nauplii. In recognition of the algal concerns and the need to address more stringent particulate removal standards in the future, the City of Wetaskiwin embarked on a proactive program to identify plant improvement requirements. Dissolved Air Flotation (DAF) and membrane technologies were selected as candidate processes for further piloting. The DAF process worked well in this application and performed significantly better than the existing Pulsator clarifiers for late-season (Fall) algae removal. However, the DAF did not perform significantly better than the existing Pulsator clarifiers in the removal of color, turbidity, organic material and early-season (Spring) algae. Membrane filtration was extremely effective in removal of turbidity, particle counts, algae and zooplankton. This paper reviews the water treatment upgrade program undertaken, and how the study findings were used to chart an upgrade path that addresses Wetaskiwin's water quality and production needs. Includes 4 references, tables, figures.