An energy efficient water- distillation device is pro- viding clean drinking and medical water at six sites in the Eastern Cape as part of alpha-phase tests conducted by drinks giant Coca-Cola Company and research and development (R&D) firm Deka Research and Development, says Deka R&D project manager Andy Racicot.

The device, invented by Deka R&D CEO and founder Dean Kamen, is a vapour compression distillation system, which distils any source of water to produce clean, drinkable water. The Slingshot vapour compression distillation system produces 850ℓ  of water a day and uses a 1 kW power source to boil the water.

The Slingshot fits into a ten-cubic-foot container and uses silicon tubes in copper-shell heat exchangers to exchange heat between hot distilled water flowing to the storage tank and the supply water being heated up as it flows into the machine. The machine slightly pressurises the water to increase its boiling point and the excess heat is exchanged with the supply water to bring it to 100 ºC. The 1 kW power source maintains the energy needed to keep the water boiling.

The resultant steam is then again slightly pressurised and more heat is added so that there is a sufficient temperature difference between this water vapour and the heat exchange to enable the steam to condense in the copper tubes, transfer heat to the supply water and then flow into the storage tank.

“The Slingshot is a continuous process system and about 80% of the supply water is distilled, with the remaining 20% used to carry the particulates and contaminants out. This effluent water could be used for irrigation, but it depends on the contami- nants in the supply water,” says Racicot.

Each Slingshot machine uses bidirectional Global System for Mobile Communications technology to send information back to the operators and to operate and monitor the machine remotely, he adds.

“Each Slingshot has two conductivity sensors to measure the total dissolved solids in the supply and distilled water, which are used to measure the cleanliness of the water produced by our machines. The Slingshot was designed to require minimal maintenance and uses basic components for easy maintenance, if necessary.”

Seven Slingshot devices have been deployed mainly at clinics in the Eastern Cape, says Coca-Cola Southern Africa technical manager Casper Durandt.

“The supply water we use in the Eastern Cape is brackish and typically has about 650 mg/ℓ of total dissolved solids. After being distilled in the Slingshot machine, total dissolved solids are less than 3 mg/ℓ. All our tests found the water to exceed the South African National Standard 241 water quality standard.”

The system can use any power source, typically a solar panel, and forms a part of Coca-Cola’s Ekocenter initiative. An Ekocenter is a multifunction centre that can be placed in rural communities to provide water, mobile-device charging and Internet access, says Coca-Cola Ekocenter GM Derk Hendriksen.

“The idea behind the Ekocenter, which fits into a 20-foot shipping container, is to be a centre for communities that can provide water, medical services, mobile device charging points and Internet access. This centre is a hub where retail and service delivery, possibly even remote government service delivery through the Internet, can occur, helping the rural or remote community to function and grow,” he says.

The Coca-Cola Company is testing the Ekocenter and Slingshot in South Africa, Mexico and Paraguay as part of its corporate social responsibility initiatives to produce as much clean drinking water as the company uses to produce its drinks (500-million litres) by 2020, says Coca-Cola Company chief sustainability officer Beatriz Perez.

“The Coca-Cola Company welcomes talks with interested parties, sponsors and potential partners. Deka benefits from Coca-Cola’s global footprint and the main target geographies for the future roll out of these Slingshot systems and Ekocenters will be developing nations and emerging economies,” she concludes.