The dream of 50 years ago becomes reality in South Africa {writer: Piet Coetzer}

“If we could ever competitively – at a cheap rate – get fresh water from salt water, that would be in the long-range interest of humanity and would really dwarf any other scientific accomplishment.” These were the words of United Sates President John F. Kennedy, almost 50 years ago. Over the last few months, people in the Southern Cape of South Africa have been surviving on exactly such technology.

A seawater desalination plant in Sedgefield on the Garden Route has been operating since 23 December: with one of the two modular units in use on alternate days between 8 a.m. and 8 p.m., the plant produced an average of 238 kilolitres per day up to 5 January.

According to Knysna Municipality portfolio councillor for infrastructure development, Andrew Finn, the plant is the largest of its kind in South Africa and comprises the latest available technology.

“This cutting-edge technology, developed in South Africa by GrahamTek, allows the plant a production capacity of 1.5ML per day, which it will easily reach if both units had to be run simultaneously.

“The plant will supplement Sedgefield’s regular water sources as and when the need arises,” he said.

The produced water is fed into the Blombosnek reservoirs where it mixes with water from Sedgefield’s regular sources, and Finn confirmed that the water meets – and in some cases, exceeds – every standard for human consumption.

Although many residents initially had expressed concern regarding the noise pollution associated with the plant, there have been no complaints. “The nearest house is 75 metres away from the plant and you cannot detect any sound from the plant whatsoever. Standing outside the container housing the operating unit, one is able to have a normal conversation without having to raise one’s voice.

“Reverse osmosis (RO) plants require intense bursts of energy in quick succession, which means that it needs a lot of electricity,” added Finn.

“The design has also addressed this issue by incorporating an energy recovery unit which, in effect, uses the same energy twice – saving up to 40% of power.

“GrahamTek is monitoring the equipment for us. Because this equipment is all computerised and self-cleaning, only one attendant is needed on-site to monitor operations. Although the 16-inch membranes need more regular servicing, the major parts only need to be overhauled every five to 10 years.”

Finn eased residents’ worry regarding the visual impact on the beach. “The top of the intake wells are at least 1.5m below beach level at spring low tide. The wells and piping are so invisible from the beach, that each point had to be surveyed and the GPS co-ordinates recorded for us to be able to find them again for routine maintenance.

“The municipality is very pleased. The costs are manageable and the quality of water produced is exceptional. We will definitely consider adding another unit to this modular system in the future,” he concluded.

At the same time, South Africa’s largest desalination plant is being created in the Eastern Cape through the refurbishment of an existing desalination RO plant for the Albany Coast Water Board. Once completed at the end of March, the plant – which is situated at the Bushman’s River Mouth near Kenton-on-Sea – would have a throughput of 1 800m3 per day.

The plant serves the Ndlambe Municipality, which caters for a population of around 50 000 people.

The desalination market is expected to become one of the fastest growing technology markets in the world over the next number of years as fresh water reserves across the world increasingly are coming under pressure.

Seventy percent of the earth’s surface is covered by water, but unfortunately, over 97% of it is too salty for human consumption and only a fraction of the remainder is easily accessible.

Climate change, drought, overpopulation and increasing industrial demands severely are depleting our available supplies of fresh water, making the proper allocation of water critical to our survival.

According to the United Nations, more than one billion people live in areas where water is scarce, and that number could increase to 1.8 billion by 2025.

Since more than 90% of the world’s fresh water is located in Antarctica – making access difficult – finding cost-effective ways to desalinate water becomes a pressing issue.

For a number of years, many experts have been proposing that desalination could be the solution to the global problem of water shortage and could guarantee water supply for the long term.

Seawater does not only offer a guaranteed supply of water, but desalination increasingly has become more affordable in comparison with the alternatives.