Students at the University of Adelaide have developed a water treatment system using cheap or free and easily obtainable materials.
The system was designed specifically for use in remote communities in Papua New Guinea, where water sources are prone to pathogen contamination.
The disinfection unit is entirely hand-made from plywood, glass tube and high-density polyethylene plastic sheeting coated with metalised plastic; the latter being the material commonly used for chip packet wrappers. The system is shaped to reflect the maximum amount of sunlight focused onto the water in the glass tube.
The reflected UVA radiation from the sun damages the DNA of pathogens, rendering them harmless. Testing for E. coli, which commonly causes diarrhea, showed the system could reduce high concentrations of the bacteria to undetectable levels in the water in less than half an hour.
According to Dr Cristian Birzer, Lecturer at the School of Mechanical Engineering, 780 million people still don’t have access to safe and clean water for drinking, cooking or washing. 1.5 million people, mostly children, die every year from consuming untreated or contaminated water.
The unit developed by the mechanical engineering students (Michael Watchman, Harrison Evans, Mark Padovan and Anthony Liew) cost just $67 in materials and can decontaminate 40 litres in four hours. As the water purification system is modular, additional units can be added as required.
The students recently won the National Student Environmental Engineering and Sustainability Award from Engineers Australia’s Sustainable Engineering Society for their invention.
If you’re interested in building your own solar disinfection system, the plans are freely available here (PDF). The team’s related paper, ‘Solar Thermal/UV Water Treatment for Humanitarian Use’ can be viewed here (PDF).
Another, but more high-tech, solar-driven water purifier for remote communities we covered last year uses solar panels and produces drinking water at a cost of 8 Australian cents per 20 litres. That system has the capability of decontaminating 1,000 litres in 24 hours.