Low cost engineering solution to high cost Cambodian waste

University of Western Australia (UWA) engineering student Ian Azaro testing a biological waste reducer (UWA).

By Jade Macmillan
ABC News, Australia

The biological waste reducer was taken to Cambodia

Transforming household waste in Cambodia into a source of fuel may not seem like the ideal holiday for most people.

But for a group of engineering students, it is turning out to be a valuable way to spend their summer break.

The students from the University of WA won first prize in an annual challenge held last year by Engineers Without Borders, an organisation that aims to improve the lives of people in developing communities through better access to technology.

The winning idea? A 'biodigester' which transforms household waste into biogas and organic fertiliser.

The project has been modelled on communities living on and around Lake Ton Le Sap in Cambodia, where last week the students, including Martin Kalkhoven, were working to implement their designs.

"We chose the challenge topic of waste management, and looked at a variety of ways we could tackle some of the area's issues," he said.

"We thought we could perhaps combine a few by looking at gasification which is a process of using heat to extract volatile gases from waste material.

"That process, of course, though would require more energy initially so on further research we came across some information about anaerobic digestion and looked at ways that this could be applied to the floating environment."

EWB's South-East Asia field officer Michael Evans says the environment itself has proved to be one of the most challenging parts of addressing the problem.

"The lake itself expands and contracts during the year which means sometimes there are houses above land, sometimes they're above water and then there are other homes that are free-floating or moored close together," he said.

"The housing situation is therefore a lot more volatile than typical housing situations around the world and so a lot of sanitation measures such as piping or sewers don't make any sense."

He describes it as a plastic bag, five metres long and 800 millimetres in diameter, the biodigester is placed underneath floating homes with the aim of catching household waste.

"Some of that is human faecal matter, some of it is plant and animal waste from cooking or other things," he said.

"That's processed and turned into one of two products, either liquid fertiliser that could be used on gardens etc, or biogas, which would be used on people's stoves."

Dumping ground

UWA lecturer Chris Rowles, who worked with the students on the project, says one of the biodigester's most important aims is to reduce the amount of rubbish entering the Ton Le Sap, Asia's biggest freshwater lake.

"The problem is that the water has become a dumping ground for all the refuse around the lake and it's starting to become polluted.

"About 70 per cent of the fish stock that's caught in Cambodia comes from Ton Le Sap and people were finding that the fish stock was depleted due to pollution and there were also a lot of health problems."

Mr Evans says another important feature of the device is its potential to reduce locals' living costs.

"Cooking in the area is done by gas and you can't pipe out gas from a lake very easily," he said.

"People have to make lots of trips to get gas cylinders which becomes expensive. By converting waste into biogas it's hoped people can become less reliant on gas supplies."

Mr Rowles says there are also added health benefits.

"Cooking fires are creating a very unhealthy environment on the lake, with people breathing smoke all the time," he said.

"This will help with respiratory problems but it will also save people about $150 a year, which, when you're earning $30 a month, is a sizeable part of your income."

Experience

Aside from the benefits the biodigester could deliver to communities in Cambodia, the students themselves are gaining valuable experience.

The group has been involved in the project from start to finish; from the initial research to the installation of the devices and the education of locals.

Mr Kalkhoven says travelling to Cambodia has been eye-opening.

"It's really given us a huge appreciateion of the difficulties non-government organisations face in getting any project off the ground," he said.

"It requires enormous amount of effort and time and you have to tread very slowly so that communication is clear at all times."

Michael Evans says it's a two-way learning process with the students and locals.

"The students come here with their theoretical knowledge or their very practical knowledge and they're learning that some things are very different to what they had imagined back home," he said.

"So in the workshops they're taking part in, I think the students are asking as many questions as the local community members."

The biodigester is already attracting attention from elsewhere, with EWB delegates from Papua New Guinea and Lesotho expressing an interest in the design.

Mr Rowles says he's proud of what the students have achieved.

"They got some credit towards their degree but the work is voluntary, they didn't have to do it," he said.

"They've finished the job now it and it seems to have worked so taking it into production in Cambodia is just the icing on the cake."