Reverse osmosis — a viable option for the mass production of drinking water?

Heavy pollution of the Mediterranean would be a real threat to Malta, as it depends on the sea to produce around 80 percent of its drinking water, the Malta summit was told. Although few other countries in the Mediterranean have such concerns at the moment, it may be just a matter of time until the region’s dwindling supplies of fresh water oblige them to. «All coastal areas in the Mediterranean, especially the south, will face water shortages in the coming years, so they need to identify new sources of fresh water,» Malta-based MAP Coordinator Paul Mifsud told the summit. More than half of Malta’s drinking water is created by the reverse osmosis procedure – an advanced form of desalination that ostensibly creates potable water of superior quality. Three reverse osmosis plants on Malta – set up between 1982 and 1991 – can produce up to 94,000 cubic meters of water per day. (Malta created its first reverse osmosis plant in the 1980s to counter the water shortage it was experiencing due to its excessive exploitation of underground sources and an explosion in tourism, which is believed to have tripled in the past three decades.) Many other Mediterranean countries, including Cyprus and Greece, have also been using reverse osmosis, but on a much smaller scale (in hotels and pensions, especially during the summer months when the demand for drinking water is higher). However, there are doubts about the impact upon the marine environment of the residue of the reverse osmosis process – a brine solution (at least three times more concentrated than seawater) with a mix of chemicals. On a tour of Malta’s newest reverse osmosis plant in Pembroke, on the island’s northeastern coast, the site’s operations manager, Charles Marmara, stopped short of conceding that this toxic brine was harmful but claimed that the damage would be limited to the particular dumping spot on the seabed. UNEP MAP Program Officer Fouad Abousamra countered that the only way to avoid intensive pollution would be to redistribute the residue across a broader sea area. However experts at the summit pondered whether, by contributing to the toxic waste being dumped into the Mediterranean – albeit with the good intentions of conserving scarce ground water supplies – we may be simply ensuring that its waters will not be suitable for any type of desalination process, however sophisticated.

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