Waterton Lakes National Park, Alberta
Municipal Wastewater Treatment
Completion Date: 2008
4,250 m3/day (1.12 MGD)
Effluent Quality Requirements:
25 mg/L cBOD5
Project Background & Challenges
Waterton National Park is located in south-western Alberta at the foot of the Rocky Mountains. It draws over 400,000 visitors a year with peak season in July to August. A lagoon based wastewater treatment, constructed in 1974, serves various business (hotels, inns, campgrounds) located near the heart of the Waterton village. An upgrade to this facility was completed in 2008 using Nexom's optAER® system.
The upgrades would allow for effluent reuse (golf course irrigation). The previous treatment facility consisted of two aerated cells followed by a storage pond. The cells were fitted with a coarse bubble aeration system which also installed in 1974. As it was, the system was unable to provide the stringent effluent requirements for re-use purposes.
The Nexom Answer
The design, equipment selection, and implementation were geared towards reducing the pathogenic content of the overall system effluent to safe levels for irrigation use. A UV disinfection system was installed (by others) at the back end of the process to accomplish this task. Nexom's challenge was to provide the high quality influent required by UV disinfection systems utilizing cost-effective technologies. The challenges were to:
- Provide a complete mix aerated cell at the front end to meet Alberta Environment's (ANEV) requirements
- Sufficiently aerate the treatment cells to reduce effluent TSS and cBOD5 to less than 20 mg/L and to digest settled solids
- Implement a Poly aluminum Chloride (PAC) dosing system prior to sand filters to form removable flocs containing absorbed suspended pollutants
- Implement a continuous backwash up-flow gravity sand filtration system to remove flocs of absorbed suspended solids
Nexom's optAER fine-bubble aeration system was used to replace an outdated coarse bubble system. An impermeable geomembrane floating baffle curtain was installed in the first cell to split it into two. The aeration in the first cell was designed to keep all solids in suspension to provide completely mixed conditions, and the second was designed as a partial mix aerated cell. Two continuous backwash up-flow gravity sand filters were fitted following the aerated ponds. A chemical injection pump to supply PAC was installed up stream of the sand filters. Chemical addition was necessary to achieve an effluent quality of 5 mg/L TSS during the algae growth season.
Upgraded System Performance
With the expansions and upgrades, the high effluent quality allows for re- use of the water for golf course irrigation within the park. This in turn reduced the loading discharged into the receiving waters. A third benefit was a reduction in surface water withdrawal from the Blakiston Creek (a bull trout spawning site). Prior to the upgrades, this creek was used to furnish water for irrigating the golf course.