On August 18, dignitaries and media from around the country attended an event hosted by Veolia Water Solutions & Technologies South Africa (VWS South Africa) to celebrate ten years' effective water re-use at the Durban Water Recycling (DWR) plant. VWS South Africa designed, supplied and commissioned this wastewater project to treat domestic and industrial sewage and wastewater to near potable standards for industrial use by high volume customers, such as Mondi Paper and SAPREF in 2001.
Some of the key figures who attended the event included, Councillor Logie Naidoo (eThekwini Municipality Speaker), Dr Gunter Rencken (Managing Director at VWS South Africa), Arnaud Gisclon (DWR Managing Director and Deputy Managing Director at VWS South Africa) and Sagren Govender (General Manager KwaZulu-Natal, VWS South Africa).
Welcoming refreshments kicked off proceedings and was followed by a presentation by Mr Gisclon on the history and success of the DWR water re-use project. Councillor Logie Naidoo shortly followed up with a speech presenting the positive effects of this project from a municipal and environmental perspective.
After a Q & A session, dignitaries and members of the press were treated to a tour of the plant and a light finger lunch.
The various stakeholders of this public private partnership include municipal utilities eThekwini Water Services (EWS) and Umgeni Water, the Marubeni Corporation, Khulani Holdings and Zetachem - part of the Omnia Group.
"This public private partnership project is a prime example of how innovative approaches to water resource and environmental management, wastewater treatment technology and institutional arrangements can yield exceptional results. It harnesses the energies of the partners and highlights the potential role that the private sector can play in water management, treatment and distribution," says Gisclon.
Located in the south of Durban in the grounds of the EWS sewage water treatment works (SWTW), the 47,5Mℓ/day capacity plant is not only environmentally-friendly, but brings significant advantages to all its stakeholders. The potable water that industrial consumers previously drew from the municipal system is now redistributed to previously disadvantaged peri-urban communities, without needing to invest in major bulk water supply and treatment infrastructure. The pollution load on the marine environment by means of recycling water that was previously discharged in the sea is also reduced significantly.
The plant employs state-of-the-art water treatment processes and technologies. Wastewater enters the SWTW, where the EWS carries out various treatment steps. These steps include screening, degritting and primary settling. The effluent from the primary settling tanks, termed feed water, is fed into the activated sludge plant that is operated by VWS South Africa. The feed water undergoes lamella settling in the first of three stages of the Veolia-patented Multiflo® treatment process. To coagulate solids in the feed water, a metal salt is dosed before polymers are added to enhance flocculation.
Thereafter, the flocculated water is fed into lamella settling tanks. As the water leaves this area, it is dosed with polyaluminium chloride to remove residual iron and enhance the filtration process. The dosed water is sent to the dual media filtration stage where ozonising occurs to breakdown remaining non-biodegradable organic compounds. The water is then polished using activated carbon filters; chlorinated and transported to a storage tank for distribution to industrial customers.
"The production of potable-quality recycled water from domestic and industrial wastewater to a guaranteed standard continuously and reliably is a showcase for advanced water process technology and process engineering," concludes Gisclon.