/ 18 January 2018

Researchers warn ‘purified’ Cape Town sea water will be contaminated

Vaal water treatment plant.
Vaal water treatment plant.

After the City of Cape Town spends at least half a billion rands to build desalination plants, the “purified” seawater these produce will have been cleared of little more than floating nappies and junk before it is declared safe to drink — despite the presence of organisms such as E. coli — South African researchers have warned.

“Almost no treatment, other than screening for large objects like nappies, is done on the sewage being released into the ocean hourly in large volumes all along our coastline. Moreover … many inland sewerage facilities are not working properly and the effluent released from these poor facilities are highly contaminated and polluting our rivers and dams,” University of Western Cape chemistry professor Leslie Petrik told the Mail & Guardian this week.

“This effluent is also being transported to the ocean. Any water intake from river, dam or ocean will be contaminated,” Petrik said.

Last year, Petrik and other researchers from three South African universities published an article in the South African Journal of Science on the probable public health risk posed by the planned desalination plants in Cape Town.

Asked how the city plans to protect its citizens from being exposed to the pollutants in desalinated seawater, Cape Town mayor Patricia de Lille said the water would meet the specifications of the country’s national water safety standards. “All plants will comply with national legislation, which also provides for some fast-track measures for disaster relief projects such as the city’s emergency projects,” De Lille told the M&G.

But the safety standards set by the national water department do not require testing for harmful organisms in the desalinated sea water, which means the presence of E. coli and Staphylococcus aureus is technically lawful.

E. coli is known to cause food poisoning, and staph infections can lead to boils and oozing blisters.

“The biggest problem is that our national water guidelines do not require statutory testing for persistent pollutants,” Petrik said.

“So the city can claim the water is within specifications but would not have proved the water is adequately purified from persistent chemical compounds if they did not test for … pharmaceuticals, pesticides and disinfectants that are being dumped into the ocean with the sewerage released through the marine outfalls.”

De Lille acknowledged this, and said the city had appointed an emergency water augmentation environmental monitoring committee, which includes national, provincial and local government officials, to monitor the health risk.

“There will be minimal risks to public health and safety, and work will comply with the applicable national health and safety regulations. The city will monitor the site and regularly test the drinking water that is produced,” De Lille said.

Petrik believes treatment options such as ultraviolet light and ozone to break down residual contaminants are essential for ensuring the safety of the desalinated water.

“This combination is relatively expensive and not super-effective, but does partially degrade organic compounds. However, there are other, more efficient, advanced oxidation systems that are cheaper to implement,” she said.

The researcher found that the seawater that is being earmarked for desalination is polluted after analysing samples collected by long-distance swimmers, kayakers and the Clifton Ratepayers Association.

These pollutants pose a more serious threat than the plastic in the world’s oceans does, Petrik contended, because “the compounds go right into the cells of all living organisms and disrupt the endocrine function”.

“[This] causes sterility or feminisation, cancer or deformities. There are thousands of manmade chemical compounds that are being released by the tonne into the environment because of our daily habits such as washing, cleaning and disinfecting,” Petrik explained.

The plan to remove the salt from seawater to make it drinkable was described as a last resort by the water department’s national water research commission in 2012. Because of the amount of electricity used in the desalination process, the technology is extremely expensive and would significantly increase the price at which the water would have to be sold.

At its most conservative estimate, the price of one kilolitre of water would be about R5.80, an official from the water department, who was not authorised to speak to the media and therefore requested anonymity, confirmed to the M&G.

But the City of Cape Town appears to have run out of options, and water supply is expected to reach critical levels by April, when the taps may have to be turned off and residents will have to queue at one of the 200 collection points set up around the city.

The city council has commissioned the construction of three desalination plants at Monwabisi, Strandfontein and the V&A Waterfront, where it will be located in “an open-air parking lot”, De Lille said.

And as “day zero” looms over the city, the council has had to cordon off the building sites because of the rush to finish the projects.

“All construction areas will be clearly demarcated and will be off limits to the public. Any pipework that is not underground will be clearly marked. The plant has been designed to ensure fast-tracked construction and production, but with the smallest possible construction footprint,” De Lille said.

The tender for the construction and operation of the plants was awarded to Water Solutions Proxa JV — a multinational company that boasts Prince Jean of Luxembourg as its nonexecutive director.

The Monwabisi plant’s construction and operation will cost R260‑million, and Strandfontein will cost R250‑million. These two plants are expected to start producing desalinated water next month, De Lille said.

The city did not give the cost of the tender for the V&A Waterfront plant, where construction started this week, but said it would start producing desalinated water in March.

The Monwabisi and Strandfontein plants are expected to provide seven million litres of water, or 7 000 kilolitres, each day for two years, after which they will be shut down.

The city is funding the construction and operation of the plants, and will also buy water from Water Solutions Proxa-JV.

Without including the costs of the V&A Waterfront plant, purchasing the water from the multinational will cost some R290‑million over two years — escalating the cost of the entire deal, and the payday for Water Solutions Proxa JV, to close to a billion rands.