Ozone gas to treat Tshwane Municipal Water

The equipment produces ozone from oxygen and is supplied by Swiss company Ozonia through its South African agents, Ozone Services Industries (Pty) Ltd (OSI). It is a key component of the process upgrade for the Roodeplaat treatment plant and will be used to improve the quality of water supplied to citizens, says Mike Hughes, a director of PCI Africa, a member of the joint venture providing the solution. The new equipment was manufactured in Switzerland and tested in the United States before being shipped to South Africa. PCI Africa expects to have completed the installation in the first quarter of 2012.

Dr Mias van der Walt, from Temba Roodeplaat Consulting Consortium, the consulting engineers on this project, says that the new system will complement existing conventional water treatment techniques. “Ozone treatment will be used when necessary at Roodeplaat to provide advanced disinfection, help control taste and odour, and remove colour,” he says.

“South Africa is one the world’s most water-stressed countries and our municipalities have a challenge on their hands when it comes to providing drinking water of an acceptable standard,” says Ian Wright of OSI. “This system uses the natural power of oxygen to improve the quality of drinking water dramatically without generating any unpleasant or harmful by-products.”

The state-of-the-art treatment kit is the very latest incarnation of Ozone technology that is already proving its worth in a country with limited water resources and high pollution levels, especially of iron and manganese. Other municipalities and water treatment plants using ozone to treat drinking water include Rietvlei, Vaalkops, Midvaal Water Company, Delmas and Plettenberg Bay.

Midvaal’s Marina Krüger says that they originally commissioned the system to remove dissolved manganese and iron. “We then realised that ozone acts like a broad-spectrum antibiotic for water so, aside from manganese and iron we use it to remove colour, tastes and odour, micro-organisms and algae as well,” she explains. “I wouldn’t want to use water from the Middle Vaal without ozone.”

Midvaal’s raw water is drawn from the highly polluted section of the Vaal River between the Barrage and the Bloemhof Dam, and ozone treatment is used to boost conventional processes to provide the potable water this growing area needs. Krüger adds that since 1985 she has noticed that the availability of the specialist skills needed to keep the ozone plants optimised and maintained has improved considerably. “Everything used to be totally imported, but now local skills are available, which is a huge benefit,” she says.

OSI’s Wright adds that the company recently launched its homegrown Biozone Nokak Sewage Treatment Plant to provide an affordable, compact way for South Africa to combat its growing water shortage. “Our physical product is 100% South African and uses a completely natural process that requires no chemicals or regular emptying to treat sewage,” explains Wright.

A single Biozone Nokak Sewage Treatment unit can process up to 300 cubic metres of sewage daily. “This is a way for a medium-sized hotel, a cluster of small houses or a large game farm to deal with waste without polluting scarce water resources or putting further strain on conventional treatment resources which themselves are heavy users of water,” says Wright. “We need innovative solutions to this problem.”
UShaka Marine World also uses ozone to disinfect its water, as do most aquariums worldwide, while the process is well established in leading global municipalities like London, Paris and Los Angeles.