Australasian Science: Australia's authority on science since 1938

How a Chip Packet Can Sterilise Water

By Magdeline Lum

Chip packaging is providing a cheap material for a water purification system in the Highlands of Papua New Guinea, and a “salmon cannon” is helping salmon swim upstream.

A group of University of Adelaide mechanical engineering students and staff have designed a low-cost water treatment system that is easily constructed in remote communities in Papua New Guinea (PNG). This water treatment system consists of foil chip packets and a length of glass tubing.

The low-tech water treatment system exploits UV-A radiation to kill pathogens in water in a continuous feed set-up. The materials chosen are readily available in PNG. The team’s motivation for design and implementation was to avoid what is known as a “white man solution”.

Mechanical engineering students Michael Watchman, Harrison Evans, Mark Padovan and Anthony Liew first designed tested a workshop-manufactured system using high quality materials. They then designed a handmade low-tech version using plywood, a glass tube and high density polyethylene plastic sheeting with foiled chip packet wrappers. The plastic sheeting was specially shaped around the glass tubing to maximise the amount of sunlight reaching the water in the glass tube. The total cost of the system is $67.

“Our priority was to develop a system with, and not just for, the end-users,” says Dr Cristian Birzer, Lecturer in the School of Mechanical Engineering, who supervised the students with Dr Peter Kalt. “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.”

The team worked with Childfund Australia to find out about the local conditions in the highlands of PNG. Many villages use communal rainwater tanks to collect water in the wet season. In the dry season, water is supplemented with water from rivers. Both of these sources are prone to harbour pathogens.

“Worldwide, 780 million people still don’t have access to safe and clean water for drinking, cooking or washing,” Birzer says. “Consumption of untreated water exposes people to a range of contaminants, including faecal-borne pathogens. It’s estimated that 1.5 million people – 90% of them children – die every year from consuming untreated or contaminated water.”

The system is able to reduce high concentrations of pathogens to undetectable levels in water in under 30 minutes. A single system can treat 40 litres in 4 hours. It is also modular in design, so additional modules can be added to enable treatment of greater quantities of water .

The project was sponsored by Santos and recently won the students the National Student Environmental Engineering and Sustainability Award from Engineers Australia’s Sustainable Engineering Society.

The Salmon Cannon

The annual migration of salmon back to their spawning areas upstream is becoming increasingly difficult with human development – particularly the construction of dams. In return, people have spent time and energy over the years carrying salmon upstream by hand, truck, aeroplane and helicopters.

Now there is the possibility of a new and possibly more efficient means of transport: the Salmon Cannon. Whooshh Innovations has designed the Salmon Cannon to carry the fish gently upstream to their destination. The tube sucks the fish from the water and slides them at approximately 35 km/h to their destination unscathed.

The Salmon Cannon has been modified from an existing device designed to move fruit and vegetables gently without bruising them. The name of the device is a misnomer as the mechanism is based on a pressure differential to move the fish upstream. Salmon have been seen swimming freely into the tunnel entering the cannon and are able to swim once reaching upstream.

The proof of concept has been put into action at Columbia River in Washington.