Distributed by The Azanian Water Foundation P O box 68 Woodstock 7915 How to get fresh water from the sea The technology is so simple that given the pots, vessels and a plastic sheet, even a child can assemble them to obtain healthy potable water from seawater. It appears too simple to be true! That is why Felix Ryan’s water purification process has found takers among slum dwellers in water starved Chennai or drought hit villagers in Gujarat, Sierra Leon and Somalia where it has been tried, tested and proven to be successful.. The technology is so simple that given the pots, vessels and a plastic sheet, even a child can assemble them to obtain healthy potable water from seawater. Water distillation is the single most effective method of water purification used today, and can be used throughout the world on all types of incoming water. Unlike other water treatment methods such as carbon filters and reverse osmosis, water distillers are effective on virtually all contaminants and are not dependent on water pressure, water temperature, pH, or chlorine. Water distillers can even be used on water containing bacteria and parasites and still produce safe, 99.9 percent pure water. While the reverse osmosis (RO) method requires heavy machines, electricity, delicate and costly membranes and non-renewable energy making it economically not viable, Ryan’s technique works on the simple alcohol brewing technique of evaporation and condensation. This desalination (distillation) technique can be done by individuals at home. Take a steel container (40cm deep and with 40 cm diameter), and fill it with about 20 litres of seawater. Inside this container, place a smaller container (20cm deep and 20 cm diameter) with its rim extending well well above the surface of the seawater. seawater. Place a non-reactive poly-propylene sheet sheet (80cm X 80 cm) over the bigger drum in such a fashion that the sheet sags in the centre and forms a cone pointing towards the centre of the smaller drum). Press the ends of the sheet against the rim of the big tub and tie it up with a rope strip or ribbon. Pour seawater into the cone to serve as a coolant facilitating condensation as well as to give weight to the cone and keep it in place. Place a weight insidee the smaller drum to prevent it from rising or floating. The entire apparatus insid apparatus can be set in the sun throughout throughout the day. Seawater Seawa ter in the large container container vapou vapourizes rizes during the day. The vapour hits the inner side of the sagg sagging ing plastic sheet along the sides of the cone, condenses and drips into the smaller container. Water collected from the smaller drum is pure water. To hasten the process, try variations like solar reflectors or fired with cheap fuel like foliage briquettes that can burn for long (Fuel briquettes may be made by crushing foliage like tea leaves and making it into lumps after mixing it with tree gum. Tamarind seeds, roasted, crushed and boiled yield good gum). To conserve fuel, the contraption may even be placed atop a steaming rice-pot, so that seawater gets heated up simultaneous to food being cooked. “The idea is not to desalinate sea-water, which removes only the particulate salts, but to distill sea water, which gives totally pure water”, Felix Ryan says. Even the water we get as mineral water is produced by machines that remove just the salt, suspended particles and some harmful microbes. It still retains pesticide traces, heavy metals, colliform bacteria, heavy metals such as chromium, cadmium, arsenic, selenium, mercury, iron, or aluminium, which can wreak havoc on human tissues. “When water is distilled from sea water, we get pure water, purer than rain water.” Ryan has devised fourteen variations to suit different situations. He has also been appealing to state governments to build cement tanks three cubic metres in size all along the coastal belt from which government or private takers could supply water to homes or commercial establishments for desalination. “It is not practical to take healthy water in metal or concrete pipes and distribute it to millions of homes. Water supply should be de -centralised”, Ryan says, adding, “the safest and cheapest method is desalination”. Ryan is working on a centralised desalination cum distillation unit that can produce potable water from seawater to cater to the needs of an entire apartment block. This installation, the Terrace Still, can be set up on the terrace, and can generate 500 litres of water per day with mere solar heating, and additional quantities with by using fuel. The water can be stored in tanks and the purity maintained further by adding duckweed, a common, tiny floating plant with pink flowers that feeds on dissolved salts in water into the water tanks. Felix Ryan is a Chennai-based UN consultant and the Chief Monitor, Survival by Sea Water Global Monitor. The United Nations conferred the Global 500 Honour on him in 1989 in recognition of his path-breaking innovations such as this water purification technique. A `poor man's technologist' as he is called, his project is simple and requires hardly any investment based on a simple evaporation and condensation principle. Ryan’s water desalination and purification apparatus and its working is elaborately discussed in his manual ‘How to convert Sea Water into Drinking Water’. The manual may be obtained by writing to the Ryan Foundation, 15, West Mada Street, Srinagar Colony, Chennai – 600 015. Tel: 2235 1993 or from: Books of change, 139, Richmond Road, Bangalore – 560 025. Tel.: 091 080 5586682. E-Mail:
[email protected]
