Safe drinking water is the main scarcity after any disaster – whether natural or manmade. In many situations surface water is available but is contaminated with harmful diarrhoeal germs of diseases like cholera, typhoid, paratyphoid, dysentery, etc. If the water is not contaminated by industrial wastes and insecticides, and if it is not saline (a problem only in coastal areas), destruction of diarrheal pathogens can render the water drinkable. For this, one needs to raise the water temperature to 60degC and maintain it for 30 minutes, the process being called Pasteurisation. At higher temperatures, the time required goes down drastically. The inventors of LifeRoll had designed and developed several models of low cost Solar water Pasteurisation devices earlier that can raise the temperature of 5 to 10 litres of water to much more than 60degC in clear sunshine with solar radiation above 700W/sqm, available in many regions of the world. The devices are simple low cost versions of solar flat plate water heaters employing ‘Green House Effect.’ The destruction of harmful pathogens has also been verified through extensive microbiological tests. About 300 families of a river gypsy community made the devices themselves and used these successfully for several years, indicating its acceptance.
The LifeRoll (Figure-1: Schematic, Figure-2: mechanism, Figure-3: handmade prototype) has been designed based on the insight developed through years of research. It is made of four transparent and one black polythene sheets, all sealed on all four sides to make four chambers– one for water to be treated and the rest three for air – one below the water chamber and two above. The black sheet lines the bottom of the water chamber. Tubes come out of the chambers, one each for the air chambers and two for the water chamber. Absorbing solar radiation, the black sheet heats up which in turn heats up the water layer immediately above. The upper polythene covers allow visible and short wave infrared radiation form the sun to pass but blocks the long wavelength infrared radiation given off by the heated water, thus trapping in heat; the ‘Green House Effect.’ Heat loss is prevented through the air chambers below and above the water layer. Thus heat energy continues to increase in the water mass and its temperature rises. Our prototype ‘LifeRoll’ gave above 65degC in clear sunshine.
When not in use, the device can be deflated and the water taken out. It can then be rolled into a small package for easy storage and transportation. Since it saves life; therefore, the name, ‘LifeRoll’. It can be a part of a ‘disaster kit’ for people living with regular natural disasters like floods, cyclones, earthquakes, etc. The flood water itself can be made drinkable using LifeRoll. Besides, any relief team can drop packs of ‘LifeRolls’ in disaster areas from a helicopter. Adventurers may also use this device. Therefore, if made in large numbers through an industrial endeavor, ‘LifeRoll’ may become a crucial product saving lives of people throughout the world.