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Not a Drop Wasted

Urban water systems risk running dry. Can research help?

By Jordhana Rempel, '11 BA

July 28, 2018 •

Water - or the lack of it - became international news this spring when Cape Town, South Africa, forecast Day Zero, the day the city's taps would run dry and people would have to start lining up for water.

Severe rationing has pushed that date back to 2019, but city officials say the crisis isn't over. Residents continue to be restricted to 50 litres per person a day. (To put that in perspective, a 90-second shower, a couple of toilet flushes and your cooking and drinking water for the day add up to nearly 40 litres.) Cape Town isn't alone. Globally, water scarcity affects four out of every 10 people, according to the World Health Organization. Water security is a growing problem in many countries, whether it's due to drought, lack of infrastructure or melting glaciers.

Chris Arnusch, '99 BSc(Spec), is one of many researchers, including at the U of A (see sidebar), who are working to keep the taps running. At the Zuckerberg Institute of Water Research at Israel's Ben-Gurion University of the Negev, Arnusch is applying his expertise in membrane research - the science of how membranes work to filter or separate types of molecules - to help the arid country improve its water security.

Waste not, want not

Water is a resource everybody needs, Arnusch says, and large countries need water management that's "above the individual."

"Israel has good water management," he says. As elsewhere, the majority of Israel's water is used in industry and agriculture, but unlike elsewhere, 90 per cent of the country's water gets treated and reused. What goes down the sink in Israel eventually finds its way to fields and factories. (Spain reuses about 30 per cent of its water, Arnusch says, but the amount of water reused in most other countries is negligible.)

Another major source of Israel's fresh water - 30 per cent - comes from the desalination of seawater. But desalination plants come with a major drawback: bacteria grow on the membranes that filter salt from seawater, clogging them up and making frequent replacement necessary. Desalination factories create dumps full of old membranes.

A problem solved

"To have good water management, you need to innovate," Arnusch says. And, as sometimes happens, a chance finding led him and his team to major innovation.

In 2014, another research group was using a laser to cut through a polymer surface when they noticed the process created a black byproduct, which turned out to be laser-induced graphene, or LIG. Serendipity struck again when Arnusch's team bought the laser. "We didn't know how to work it properly," he says with a laugh. The team did not focus the laser on the polymer surface, so instead of coming to a single point, the laser hit the surface multiple times.

There was utility to the misstep: it created an LIG coating on the polymer. The team researched possible applications and found they could coat the polymer membranes commonly used for water purification systems. And since bacteria do not grow on LIG, the process prevents bacterial clogs. Arnusch believes the technology will go a long way to preventing the massive dumps of fouled membranes.

Avoiding Day Zero

Arnusch says the situation in Cape Town illustrates that it's easier to plan to avoid a crisis than to react to an imminent one. Most Canadians have ready access to fresh water. But some areas in Western Canada can be affected by droughts: last summer, communities in southern Alberta faced 40 water shortage advisories during one of the hottest, driest summers on record. Among Canada's Indigenous communities, more than two-thirds face moderate-to-high risks of contaminated drinking water, the Council of Canadians reports. In May, a U of A-led report, the 2018 State of the Mountains Report, called for policy-makers to begin planning for the inevitable disappearance of glacier-fed rivers based on changing climate.

To prevent our own spin on a Day Zero water crisis in Canada, we all need to look for ways to use water more efficiently, prevent water contamination and restore water already polluted, Arnusch says. "I don't think Canadians will have a problem with water as long as they take steps now."

"I think every country needs innovation as well as management, so we can ensure water security in the future."

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