Major Boost For Cape Town Water Supply
The Potsdam Waste Water Treatment Plant in Milnerton, built at a cost of R19 million, is expected to generate an additional 38 million litres (mega litres) of non-potable water per day for the Blaauwberg area.
At its official opening today, 22 June 2006, Councillor Lionel Roelf, Mayoral Committee Member for Trading Services, said that the City's rising demand for water will soon outstrip supply, if nothing is done to explore alternative water resources.
"Together with measures to reduce water consumption, the City is looking at the desalination of sea water, the exploration of deep aquifers, and the recycling of waste water and sewage - to name but a few.
"Of all these options, the re-use of treated effluent is one of the most cost-effective. Two thirds of the City's total water consumption ends up in 22 treatment works across the city from where the final effluent is discharged back into the environment.
Currently an average of only 30 million litres per day - or 7% of the City's total waste water is used during summer - replacing potable drinking water. It thus makes good economic sense to recycle waste water into non-potable water for irrigation purposes. This is being done by City Parks, and an increasing number of golf courses, sports facilities and industries," says Roelf.
According to Anic Smit of the City's water reticulation services and project manager for Potsdam, the City undertook an investigation two years ago into the refurbishment of the treated effluent systems at its various waste water treatment works (WWTW).
"Although the philosophy is not new and some schemes have existed for over 40 years, it was never a formal Council service and therefore never enjoyed high priority," says Smit.
The study revealed that the potential for treated effluent use could be expanded to 170 million litres per day at an average cost of less than R2,24 per kilolitre - or a third of the cost of fresh drinking water.
This amounts to 40% of the total summer waste water usage - and 30% of the annual supply from the new Berg River Dam project.
The first extension was initiated in 2003 at the Bellville WWTW, increasing the available treated effluent from four million litres to seven million litres per day. In 2005, the re-use of effluent at the Parow and Kraaifontein WWTW was increased from 1,2 million litres to 3,7 million litres per day.
In June 2005, a contract for the upgrading of Potsdam's treated effluent system was awarded, leading to the creation of one of South Africa's most technologically advanced waste water recycling facilities.
The refurbishments at Potsdam include:
- two new pump stations capable of pumping up to 40 million litres per day
- a highly sophisticated filtration plant to remove all suspended solids
- a bulk supply pipe network of 4km
- a 40 million litre storage reservoir (the size of a rugby field) built with environmentally friendly materials and techniques
- a new intake chamber with floating skimmer.
"The new system will increase the treated effluent at Potsdam from 17 million litres to 24 million litres per day. All 17 million litres per day will replace potable fresh water and a further 20 million litres per day will be made available for agricultural use," says Smit.
Situated in Koeberg Road, opposite the Chevron oil refinery, Potsdam currently provides non-potable water to the Milnerton Golf Course, the Theo Marais sports fields, Sappi Paper, four schools in Milnerton and Table View, public open spaces and the Table View beachfront dunes. Potential new users include the oil refinery, Kynoch and local farmers.
The scheme also provides the bulk infrastructure for future extensions to other industrial users and residential developments in the area. A new development on the farm De Grendel will also utilise the treated effluent and install a dual water reticulation network for domestic irrigation.
Prior to the installation of the treatment system, Potsdam's effluent water was discharged into the Diep River estuary which feeds into Milnerton Lagoon.
"This is without doubt, the City's flagship effluent treatment facility and its success will lead to the upgrading of our other waste water treated effluent works throughout the metropole," says Cllr Roelf.
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