Armed with plywood, a glass tube and some empty chip packets, mechanical engineering students from the University of Adelaide have developed a low-cost water purification system capable of killing off harmful bacteria. The solution is designed for remote communities in Papua New Guinea (PNG), an area where water is particularly susceptible to pathogen infestation.
The water treatment system was developed in collaboration with ChildFund Australia, an organization dedicated to promoting children's rights across the globe. One of the team's main design focuses was to provide a solution that could easily be adapted by local communities in PNG. As such, it was critical that the materials were both cheap, light and accessible.
"Our priority was to develop a system with, and not just for, the end-users," says Dr Cristian Birzer, lecturer at the School of Mechanical Engineering and supervisor of the project. "We wanted something where we could provide design guidelines and let the local communities build and install their own systems using readily available materials that could be easily maintained and replaced."
As a starting point, the students built a system using high quality materials. The water runs through a piece of piping, which rests in a trench-shaped structure coated in reflective metal. This material directs the sunlight onto the water, harnessing its UVA radiation to kill off pathogens. They then replicated this model with the plywood, glass tube and high-density polyethylene plastic sheeting coated in the chip packet wrapping, shaped to capture the maximum amount of sunlight and direct it onto the water running through the glass tube.
The students found that the rudimentary version worked just as well as the high-quality one, and was a very cost-effective solution at AU$67 (US$60). In testing, the system was able to reduce high amounts of E-coli to undetectable levels in under 30 minutes.
"The system can successfully treat close to 40 liters (10.5 gal) in four hours and the beauty is that it's designed to be modular, so more modules can be added for greater quantities of water," says Dr Birzer.
The University of Adelaide students Michael Watchman, Harrison Evans, Mark Padovan and Anthony Liew took out the National Student Environmental Engineering and Sustainability Award from Engineers Australia's Sustainable Engineering Society for the project.
Their research is set to be published in the journal Procedia Engineering.
Source: University of Adelaide
The level of infrared absorbed is not sufficient to treat the water; infrared and UV radiation are separate treatment methods. There is a mechanism where high temperatures coupled with UV radiation significantly increases treatment capabilities but we could not effectively achieve this.
A variety of tube materials were tested for UV transmission, with Pyrex being the most economical option.
WHO recommends a SODIS method with 2L water bottles, which works with the same mechanism. This system improvises on this, turning it into a communal solution (multiple social advantages) with higher water production rates, and improved reliability and flexibility.
For some night cap reading ... http://mecheng.adelaide.edu.au/humtech/resources/
If in the devices pictured in this article, the water took 30 minutes to gravity flow through the glass tube, there must be a pretty small aperture at the bottom.
The systems are modular, so 40L for one module, 80L for two so on. We tested with one and three, and yes they are valve throttled to small flows, some cases it is only dripping.
Another issue for this type of sterilisation has been murky water quality. Have you considered the need for a filter to remove solids from the water before sterilisation in the field?