Cape Town - Engineers at the African Utility Week in Cape Town unveiled a first-of-its-kind desalination wastewater plant on Thursday that, they say, could make turning seawater into drinking water more affordable
and palatable for budget-stretched cities.
Titus Kasie, mechanical engineer at eThekwini municipality, said his plant, which had its public participation day in Durban, significantly reduces costs by only producing 50% of its water from the ocean. The other 50% is from treated wastewater.
The plant, the first of its kind in Africa, would kill two birds with one stone, Kasie said. By mixing wastewater with desalination, it cuts the power demands - one of the chief cost barriers to desalination - from 4.4 kilowatt hours/cubic metre to 2.6 kWhr/m3. And by mixing wastewater with desalinated water, they hope people will be less reluctant to drink recycled water.
“When you tell someone they are drinking 100% reused water, public perception is not that good,” said Speedy Moodliar, senior manager of planning at eThekwini. “We lost projects because of that.”
The costs for the medium-sized plant would be R16 per cubic metre including capital expenditures, he said, but would fall to between R11 and R11.50/m3 if scaled up to a full-size 100-megalitre operation.
Moodliar said the plant was attracting international attention, with funding coming from Japan and officials from Spain, Israel and Norway flying to Durban to learn more.
Israel may be the global leader in desalination technology, Moodliar said, but they don’t yet make wastewater for human consumption.
The plant has also attracted the interest of Cape Town.
In an interview after her speech, Gisela Kaiser, executive director of utility services for the City, said the city was pursuing long-term alternative water resources as climate change increases the long-term likelihood of drought.
“Cape Town has a serious job,” Moodliar said. “Now we’re seriously looking at reuse”.
Throughout the two-year-long Cape Town water crisis, city officials have said that desalination is too costly.
“Not only is it impractical to put aside billions of rand for a not-so-rainy day that might not come about, but there are more pressing humanitarian and economic needs,” Kaiser said at the same summit.
She added that “there is no way (that) a water supply scheme such as a desalination plant could be built to scale quickly enough to compensate for such a drought”, but that the city has now started looking at alternative measures.
However, mayoral committee member for informal settlements, water and waste services and energy Xanthea Limberg said plans for a desalination plant based at Koeberg Nuclear Power Station, have been ongoing for five years.
She said the plant is already in existence at Koeberg but not yet operational, although the first phase will begin within the next few months.
“The plant is in the process of providing yield within this year,” she said, adding that the plant is nuclear powered. There are also plans for a second mobile desalination plant to be constructed along the northern West Coast.
This plant will be the smaller of the two.
Currently, the appointed service providers are busy with the design and specifications of this smaller plant and a tender for construction will be advertised in June.
Both plants are owned by the city.
Julius Steyn, chief executive of the South African branch of GrahamTek, an international desalination plant company, said Cape Town’s view of the technology is outdated.
He said his company’s plants could supply water at a “much cheaper” rate than the current price for non-indigent families by installing small plants at ports and scaling them up every three months.
He said GrahamTek would cover all capital expenditures involved with building the plant but did not speak of daily operational costs, one of the primary costs associated with desalination.
* Additional reporting by Tanya Petersen