Desalination and Brackish Water Treatment Technologies and Solutions
It is unlikely that any inhabitant of the Western Cape will have forgotten the “day zero” drought when the taps in the Mother City came close to running dry. Only the timely introduction of a temporary desalination plant prevented what would otherwise have been a national disaster. The event created a greater awareness of the semi-arid conditions typical of many parts of South Africa and the urgent need for more efficient water management.
Removing the dissolved salts from seawater to render it potable is not a new concept. The Ancient Greeks began filtering it through the earth to achieve this around 460 BC. By the end of the first century, they had started using distillation to speed up the process and produce larger quantities of drinking water. By the mid-nineteenth century, many naval vessels installed stills for desalination purposes. The first large-scale plant was built in 1930 in the Dutch Antilles However, construction of commercial-scale plants only began in earnest after the end of the second world war in 1945. These facilities also relied on boiling the seawater and cooling the vapour to produce a salt-free condensate.
Since those early days, domestic, commercial and industrial water consumption has continued to grow, leading to increased reliance on distillation technology to treat seawater and brackish sources. Unfortunately, the high energy requirement for this procedure has meant that desalination plants cannot compete economically with traditional water purification methods due to the markedly higher production costs. In addition, we are now faced with the need to limit energy consumption if we wish to avert global warming. There have been partially successful attempts to reduce the cost of evaporative technology. These include multi-stage flash distillation (MSF) and multiple effect distillation (MED). However, while these newer methods have proved more energy-efficient, a new technology developed during the ‘60s is rapidly replacing these albeit effective but still costly methodologies.
Today, most new desalination plants employ reverse osmosis (RO), an adaptation of the process used by plants to regulate the movement of water. In osmosis, water flows through plant cell walls from areas of low solute concentration to areas of higher concentration to maintain equilibrium. In RO, applied external pressure forces the process beyond the point of balance, thus separating the dissolved salts and water completely.
Although membrane technology is widely used to prepare water of exceptionally high purity for the pharmaceutical and food and beverage industries, RO has significantly reduced the cost of treating seawater and brackish sources. Watericon is an established leader in desalination and other applications of membrane filtration technology. We invite you to learn more about our world-class water treatment solutions.
