Dr. Pierre Côté had just completed his PhD in civil engineering and was doing post-doctoral work for a company in France when he first investigated the technology that would change his life. He watched, fascinated, as he used a membrane to filter and purify water.

"I was very excited," Côté recalls. "It's pretty well the reaction of everybody that starts working with membrane . . . it does such a great job in terms of water quality, and is relatively easy to use, that nobody goes back to conventional treatments."

Membrane filtration technology isn't new. The human body has natural membranes, such as those in the lungs and kidneys, that filter harmful particles and contaminants and purify oxygen and blood. Kidney dialysis machines use polymeric membranes - similar to those used in ZeeWeed® water treatment systems - to filter the blood of dialysis patients.

Membrane technology became commercialized for water treatment about 10 years ago. But initially, the technology was much more expensive than conventional water treatment methods and it had technical problems.

Côté, whose father ran an automotive parts business in Drummondville, Quebec, grew up fixing problems and building things.

"I always had a project going when I was young," Côté, 47, recalls. "I think I was fascinated with construction machinery . . . that's how I ended up in civil engineering."

Côté specialized at first in sanitary engineering and he was more interested in the structure of dams than the intricacies of water treatment. Then, in the 1970s, he read the book Limits to Growth, by the Club of Rome, which detailed the environmental consequences of a rapidly growing global population. "I think it was a turning point for me to decide to go into environment and water treatment."

In 1989, Côté joined ZENON Environmental Inc., the company created by his PhD supervisor, Andrew Benedek. For three years, Côté researched and developed new membrane-based products, including ZeeWeed.® He left ZENON in 1992 for five years to work in France as research program director at Compagnie Générales des Eaux, the world's largest water company. He led a team that won a French Academy of Science prize for a project on nanofiltration in 1995.

Côté moved back to Canada in 1998 to the position of chief technology officer at ZENON.

ZeeWeed® is a unique, all-purpose filtration membrane that can be used to purify ground or surface water for use as drinking water by municipalities or as process water by industry, and treat municipal and industrial wastewater before discharge to the environment.

Membranes are thin films containing billions of microscopic pores that filter water by removing tiny particles such as clay, organic debris, metals, parasites, bacteria and viruses.

ZeeWeed® is a membrane in the form of a hollow fibre, presented in a shell-less, open module that is immersed directly into the water to be filtered. Like sea weeds, ZeeWeed® fibres float freely in water, lightly agitated by a stream of air bubbles.

The membrane located on the outer surface repels contaminants, allowing only clean water to permeate to the inside of the hollow fibres. The pressure needed for filtration is provided by a water column and a slight suction applied to the clean water side.

"The ZeeWeed® technology is a true in-tank technology that is easily installed and avoids the high energy demands of recirculating high-pressure water through enclosed membrane systems," says Michael Semmens, professor of environmental engineering at the University of Minnesota.

"The performance improvements to be gained by implementing the technology are substantial."

One ZeeWeed® module can purify enough water for about 50 people, Côté says. "At the other end (of the scale), there's basically no limit. We have systems going in now in cities of 100,000 to 200,000. And we have projects with cities of half a million to 2 million people."

ZeeWeed® "is a robust technology that is much less vulnerable (than conventional treatment systems) to operation and maintenance failures. So it is a real innovation," says Jan Schippers, scientific advisor at Kiwa N.V. Research and Consultancy in The Netherlands.

ZeeWeed® filters disease-causing microbes such as cryptosporidium and giardia ("beaver fever") that aren't removed or totally destroyed by conventional water treatment. The technology is adaptable to retrofit existing water treatment plants, and it is cost-competitive with conventional systems.

ZENON Environmental, with more than 400 employees worldwide, markets ZeeWeed® and other water treatment technologies through 14 offices in 10 countries. Côté and his research and development team plan to unveil the next generation of ZeeWeed® technology in March, 2001.

Côté's job sounds a lot like the projects he built when he was a kid. "Just coming to work is fun. It's not working," he says. "I'm doing R&D so it's always something new."