Collaboration finds solution to common industrial problem

Dawn Wiseman

Catherine Mulligan (Building, Civil and Environmental Engin-eering) and Masaharo Fukue (Tokai University, Japan) shared the same thesis supervisor, albeit at different times. That common reference led them to catch up on work and mutual acquaintances when they met at conferences.

“Eventually we decided we should really collaborate,” Mulligan said, “especially since our individual research is so complementary.”

Mulligan and Fukue are both environmental engineers with an interest in developing real solutions to contamination problems in water. Specifically, they are interested in how to remove suspended solids before they settle into the bottom sediment of freshwater bodies.

Suspended solids from urban, industrial and agricultural run-off include things like heavy metals, fecal matter, phosphorous and nitrogen. In the short term they contaminate the water; over the medium to long term they feed algae blooms (like the blue-green algae currently in many Quebec lakes) and enter the food chain. They also impact recreational use of water.

Settled solids in the sediment of the Lachine Canal have been cited as one of the issues impacting its use, which has been declining despite the large investment made to reopen it to pleasure craft a few years ago. Traffic in the canal is limited to 10 kilometers per hour to ensure the toxic sediment on the canal floor is not re-suspended.

As Mulligan pointed out, “When the solids settle into the sediment, they become both a source and a sink for further contamination, and the problem becomes chronic. ” A potential solution for the problem here may eventually be inspired by her recent work with Fukue in Japan.

During Mulligan’s sabbatical, she and Fukue began a joint Japan-Canada research project to examine ways of quickly and efficiently filtering suspended particles from water.

With a grant from the Ministère du Développement économique, de l’Innovation and de l’Exportation (MDEIE), Mulligan’s lab undertook an evaluation of filters to see which ones were most efficient. “The key is being able to remove the smaller particles without completely clogging and losing the efficiency of the filter,” she said.

In parallel, she and Fukue oversaw field testing of two pilot systems developed in Japan. The first was a 15-by-60-metre barge modified as a floating filtration plant that “processes 10,000 cubic metres of water per day.” The second was a much smaller (one-by-one-metre) solar-powered floating filter. As the significantly cheaper solution, multiple units could be used at the same time in order to increase the overall rate of filtration.

Both systems appear to work quite well. “Measurements before and after testing indicate a significant drop in suspended solids over time,” Mulligan said.

With a new three-year grant from MDEIE and a one-year grant from NSERC’s Special Research Opportunities fund, she and Fukue are looking at replicating experiments in and around Montreal. The first step is identifying areas where contamination exists.

“He was here on Thanksgiving weekend and we scouted some areas for hot spots.”

They are looking for similar locations in Canada and Japan, such as harbours and isolated bays, which are always potential sites for contamination build-up because they are sheltered from faster flowing water.

Mulligan pointed to the Technoparc area between the Victoria and Champlain Bridges as a likely testing area. “It’s an old landfill which is leaking into the river. You can smell the oil when you walk nearby.”

She and Fukue are involving a number of graduate students in the research, “One of Fukue’s recent PhDs is coming to Concordia as a postdoc in November,” Mulligan said, “and we will have another PhD student very soon.”

Ultimately, the international collaborators hope their project will lead to defining the parameters for cost-efficient, large-scale water remediation. And Mulligan loves that potential for real world results.

“It’s very exciting, one of the reasons I became an engineer.”