Wednesday, July 23, 2014

Solar-Distilled Water

IN the Prohibition Era, 90 years ago, bootleggers used clandestine stills to produce moonshine.
INNOVATION: Stuart Estaugh, national sales manager for solar still F Cubed Australia Ltd with Member for Mildura Peter Crisp at the launch of Mildura Eco-Village’s solar, water-producing still.Picture: Graeme O’Neill
Mildura’s Eco-Village now uses a sunshine-powered still to produce sparkling aqua pura from water recycled from the adjacent Mildura landfill facility.

Welcome to the future – one that might not be too far away  for people living in remote rural regions where there is no access to reticulated water, and a very limited natural water supply, according to Stuart Estaugh, national sales manager for solar still F Cubed Australia Ltd.

F Cubed built the demonstration solar still at the Eco-Village.

It describes itself as a solar water processor.

Member for Mildura Peter Crisp and Mildura Mayor Glenn Milne opened the large, modular solar still at the Eco-Village yesterday.

The still has no moving parts, and requires nothing more than a free supply of sunshine – an energy source in oversupply in north-western Victoria.

Councillor John Arnold, who holds council’s economic development and tourism portfolio, said the Eco-Village’s new solar distillation demonstration site was something industry, private homeowners and corporations should be looking at in the future.

“Water is a major issue in our region from an environmental, social and business point of view,” Cr Arnold said.

“Designs such as this show how water can be recovered and reused using solar power, with high-quality distilled water offering another option for everyone.”

The solar still is quite simple in design – each module consists of a large black metal panel covered by a thin layer of tough, UV-resistant polycarbonate plastic.

The panel faces north, and is inclined at an angle of 28 degrees – a slightly lower angle than Mildura’s latitude of 34 degrees south would normally require for a flat-plate collector, but optimal for the still’s operation.

Contaminated water is fed into each module, and the high temperature inside the absorber turns it into water vapour.

As it circulates, it  condenses on the relatively cool, hydrophilic (water-attracting) lower surface of the polycarbonate.

Because the polycarbonate slopes downward at an angle of 28 degrees, the water runs down its surface and is collected and piped to a nearby tank for reticulation around the site.

At peak operating efficiency in hot weather, each module is capable of producing up to 5 litres per hour.

It’s drinkable – purer than the water that comes out of a suburban tap – but will be used to irrigate the Eco-Village’s elevated garden bed.

In turning it back into water, the vapour leaves all its impurities behind, which are piped away, and the impurities are left behind, and any remaining contaminated water is recycled again, until it is pure enough to be pumped into a small storage tank, for use in the site’s irrigation system.

There are 70 modules in the Mildura installation, which is the largest in Victoria.

Each module has a typical output of about 15 litres of distilled water per day, ranging up to 20 to 25 litres on a very hot summer day, so the array can pipe around 1000 litres a day into the storage tank nearby.

On a hot day, it can provide up to 1500 litres of water – enough to provide for the minimum vital needs of about 10 people, based on the Brumby Labor Government’s minimum daily per-capita target of 140 litres during the Millennium Drought.


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