Beating the cold has taken on new meaning for University of Waterloo researchers who are working to help Canadian wastewater treatment plants become more environmentally sustainable.
One of the research group’s projects involves a problem at a plant in the southern Ontario community of Keswick that is subject to stringent discharge limits.
Civil and environmental engineering professor Wayne Parker, left, works with master's student Sara Abu-Obaid, one of the researchers on a project in York Region.
Specialized membranes have been added to the plant’s treatment processes to prevent virtually all phosphorous from getting into nearby Lake Simcoe, where the potential growth of oxygen-depleting algae blooms is a particular concern.
The problem is that those membranes foul faster and must therefore be cleaned more often in winter.
For the municipality that owns the sewage plant, York Region, that means higher costs in terms of both energy and labour, plus challenges keeping up with the wastewater flow when some of the membranes are out of service for cleaning.
“It’s not a trivial issue for them,” said Wayne Parker, a civil and environmental engineering professor who leads a three-year project that is backed by the federal government through the Natural Sciences and Engineering Research Council, York Region and General Electric.
Although cold is the clear culprit as wastewater temperatures in winter near those in a household refrigerator, why the fouling occurs isn’t completely understood.
Possibilities include excretions in cold weather by the bacteria that play a key role in breaking down solids in the conventional treatment process upstream of the membrane system, or that those bacteria are less efficient because their metabolism slows in lower temperatures.
Search for cause is first step
Parker and two graduate students working on the $200,000 project plan to do studies at the plant and simulations in the lab to pin down the cause, then explore ways to reduce winter fouling and its consequences.
Down the road, their findings may become valuable in many more cold-climate communities on inland lakes as concerns increase around eutrophication, or algae growth, and environmental rules tighten as a result.
A second project involving the Waterloo Engineering group led by Parker will examine how small wastewater plants in Ontario deal with sludge, or biosolids, the organic residuals of the treatment process.
Large plants employ several effective, sustainable strategies, including processing sludge to produce methane, fertilizer for agriculture or pellets to make artificial soil, but most small plants haven’t been able to adopt those technologies.
“For smaller wastewater treatment plants, research and development hasn’t progressed in a similar way,” said Parker, citing obstacles such as smaller staffs and economies of scale. “They have sort of been left in the shadow.”
Aiming for continuous improvement
Supported by and in collaboration with the Ontario Ministry of the Environment and Climate Change, Walker Environmental, the Ontario Clean Water Agency, the Southern Ontario Water Consortium, Oxford County and Waterloo Region, the two-year, $225,000 effort will examine sludge handling at about a dozen small plants in the province.
That audit will then be used to create benchmarks for small plants to evaluate how they measure up and identify ways to improve performance in areas including energy consumption, disposal costs and the quality of by-products they generate.
“It’s all about looking for ways to continuously improve the operation of these plants from a sustainability standpoint,” said Parker.
Work by the Waterloo research group on those two projects and others is expected to gain urgency as increasing emphasis on sustainability leads to more stringent regulations for wastewater operations across the country.