Canadian technologies helping to make world's drinking water safer

Canadians aren't the most likely people in the world to appreciate the value of water — compared to countries such as Saudi Arabia, Australia and even the U.S., we have lots of it. The Great Lakes alone hold 20 per cent of the world's fresh surface water, notes Rick Findlay, vice-chair of the Canadian Water Network, a federally funded research network.

But even in comparatively water-rich Canada, water is becoming a bigger issue. As the deaths and illnesses from contaminated water in Walkerton, Ont., showed 10 years ago, clean water isn't something you can take for granted anywhere in the world.

In many parts of the world, safe drinking water is at a premium or simply unavailable. In areas that do have access to fresh water, pollution from sewage and industrial waste water are growing concerns. Technology to purify water — whether it's preparing drinking water for consumption or removing contaminants from waste water — is constantly being improved, and Canadian companies are playing a significant role.

Findlay, who chaired a panel on water purification technology at the Ontario Centres of Excellence Discovery 10 conference in Toronto on May 17, says Canada contributes significantly to water sustainability. "We've got the money, we've got the brains, we've got the technological know-how."

New technology

For many years, the most common way of treating drinking water was to add chemicals — such as chlorine — designed to kill bacteria. Treating sewage, meanwhile, depended largely on letting wastes simply settle out of the water. The old methods are widely entrenched and aren't going to change any time soon, but there are new approaches starting to come into use that are more effective.

For instance, says Frédéric Dugré, president, chief executive and co-founder of H2O Innovation Inc. of Quebec City, about 10 years ago research revealed that when chlorine combines with certain organic substances in water, it can create byproducts such as trihalomethanes that have been linked to cancer.

One answer is to remove the organic substances using membrane filtration, which was developed close to 40 years ago but has only recently become common in municipal water systems.

Dugré says membrane filtration was first used for specialized purposes such as providing super-clean water needed in producing computer chips. As its cost has come down, it has found its way into industrial and municipal water treatment.

There is also a growing market in industrial water re-use, says Michael Froud, vice-president of industrial markets at Eimco Water Technologies, the water treatment unit of Montreal-based GLV Inc.

Froud, who is based in Australia, says he has clients who claim they can't expand because they can't get more water from municipal supplies. Using membrane filtration and other techniques, they can clean up to 70 per cent of the water they use and feed it back through their processes again.

Filtering water through ultra-fine membranes can remove virtually all impurities, Dugré says, though no single membrane material will do the whole job. Thus a filtration system may use several different membranes in succession.

One problem is the amount of pressure needed to push water through the membranes. It takes 900 to 1,000 pounds per square inch of pressure (the pressure in a car tire is about 30 pounds per square inch), and that takes significant amounts of energy. One of H20's current projects, Dugré says, is developing more energy-efficient technology to do this.

Alternatives to chlorine

Traditionally, chlorine has not only been added to drinking water — it has been used to kill microorganisms in waste water as well.

Producing carcinogenic compounds isn't the only problem with this approach, says Linda Gowman, chief technology officer at Trojan Technologies Inc. in London, Ont. The chlorine itself is bad for the rivers and lakes into which treated sewage is discharged.

Trojan started 30 years ago to sell systems that treat both drinking water and sewage using ultraviolet light, which renders microorganisms incapable of reproducing. The infrastructure for treating sewage with UV takes less space than that needed for adding chlorine - important to municipalities with increasing volumes of water to treat and no room to expand existing facilities. And there's no need to transport or store chlorine, a toxic chemical.

Much of Trojan's focus today is on developing UV processes that use less energy. That's a priority across the water-treatment industry, whether it's making existing water treatment processes more energy-efficient, recycling waste heat as energy or even finding ways to make fuel while purifying water. Waste water treatment, Froud notes, is a big energy user worldwide. But sometimes, water treatment can actually produce energy.

About 10 years ago, Xogen Technologies Inc. of Orangeville, Ont., was experimenting with using electrolysis to split ordinary tap water into hydrogen and oxygen gases, when a water treatment company asked if Xogen's process could be used to separate water from sewage sludge. Experiments showed it could, says Angella Hughes, Xogen's president and chief executive — and the process also "killed all the pathogens in the waste water and we did it very rapidly."

Xogen's process turns wastewater into water that meets environmental regulations, while at the same time producing hydrogen and oxygen gas and an inert solid. Xogen is about to begin a small trial at the sewage treatment plant in its hometown. Hughes says the goal is to prove the system can clean the effluent while producing commercially useful quantities of hydrogen and oxygen. Hydrogen in particular shows promise as fuel, but its potential depends on economic sources of supply.

Access to clean water is an issue that's unlikely to disappear for much of the world's population. In fact, people in many parts of the globe are turning to dirtier water supplies than they have used before in order to meet growing demand, says Gowman, so developing better purification techniques is an essential area of research and development.

"It's one of those places where people have no choice but to continue to invest," he says.