WASTEWATER
Dauphin, MB meets its cold weather ammonia level requirements using a new technology By Patrick D. Hill
W
inters in Dauphin, Manitoba, like much of northern Canada, are bitterly cold. Between December and February, temperatures routinely sink to an average low of -20°C. During this time, the city’s wastewater treatment lagoon is typically engulfed in almost a metre of ice. That’s a problem, says Jeff Hume, utility foreman for Dauphin’s Utility department. Extremely low lagoon temperatures affect the microorganisms that keep ammonia levels in check. Come spring, when it’s time to start releasing eight months of effluent into the Vermillion River, Hume has been hard pressed to control ammonia levels. “We are on a seasonal discharge schedule and only discharge four months out of the year, starting in April. The rest of the time, we store our influent. The challenge is our lagoon becomes anaerobic over the winter; our microorganisms freeze and are inactive. So, when we go to start releasing, ammonia is an issue,” Hume explains. “We definitely want and need to protect the local ecosystem.” Dauphin is known for its many national and provincial parks and lakes. Manitoba's highest point, Baldy Mountain, is located here. While the local economy is largely based on farming and ranching, Dauphin attracts a significant number of tourists. So, it’s important to protect the local splendour. Dauphin Utility is responsible for maintaining the city’s wastewater operation for a local population of about 8,000 year-round residents. The facility consists of one lagoon with seven cells and three lift stations with a processing capacity of 3.8 MLD. For aeration, the facility employs three blowers and static tube aerators that release coarse bubbles. Dauphin’s aeration equipment is roughly 50 years old and there are breaks in the submerged aeration pipes. This means aer44 | December 2021
The pilot system was housed in a small building. Winter temperatures in Dauphin routinely sink to an average low of -20°C.
ation across the lagoon is inconsistent. The equipment is also very energy intensive compared to newer technologies. Energy use and staying within regulated ammonia levels is always on Hume’s mind. “Our system is so antiquated, it’s costing us a lot of money. Taxpayers want our facility to be more cost-effective, so we are looking at doing a big upgrade.” REDUCING AND STABILIZING AMMONIA LEVELS Dauphin’s wastewater plant is regulated by Manitoba Conservation under the Environment Act of 1987. The Water and Wastewater Facility Operators Regulation of 2003 sets the standards for classification of water treatment and distribution systems. The average allowable level of ammonia in effluent is 4 mg/L. During the spring/summer discharge season of 2019, Dauphin was having dif-
ficulty meeting this number, experiencing an unacceptable range of 6-15 mg/L Although planning for a future upgrade of its wastewater treatment facility, ammonia removal took on a new urgency. Hume began researching options. He met Patrick Hill of Triplepoint Environmental at a wastewater conference and decided to get information from him on the company’s NitrOx lagoon ammonia removal system. The system excels at cold water ammonia removal, achieving an average effluent of 0.03 mg/L, well below Dauphin’s requirements. “What I liked about the NitrOx system was the small footprint. Other solutions were quite large and choosing one of them would require us to purchase additional land. The NitrOx is compact and fits our current space, avoiding a capital expense,” Hume says. “We were assured
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