Getting Membrane Performance Out of a Conventional Filtration Plant in a Small Community

摘要

The Town of Slave Lake is located in the north-central area of the Province of Alberta, Canada. The Town receives its water supply from Lesser Slave Lake. The existing conventional treatment plant was constructed in 1982 and has a hydraulic capacity of 7 ML/d (1.85 MGD). As part of the improvement program, chemical feed systems are upgraded based on jar test optimization findings. A new powdered activated carbon feed system was installed by utilizing the unused space of an old clearwell. New feed systems for polymer, acid and caustic were also installed. This enabled the Town to practice enhanced coagulation to achieve required organic removals, taste and odour control, and to stabilize plant performance. Other upgrades included incorporation of tube settlers into two of the three clarifier basins (to achieve future capacity), installation of automated sludge collection systems in the clarifiers, and the conversion of a third clarifier to a disinfectant contact tank to achieve required Giardia and viral inactivation. Filter underdrains and media were also replaced. With such improvements and the practice of optimized enhanced coagulation, the water treatment plant achieved all of its treatment goals (<0.05 NTU turbidity, <20 particles [>2 um] counts/mL). The upgrades also allowed the Town to extend the service life of the treatment facility beyond its original prediction, which could postpone a membrane upgrade by many more years. The success of this plant upgrade and process optimization enabled the conventional facility to produce water that is comparable to microfiltration-produced water. This paper describes the above upgrades and implementation of upgrades while maintaining production