Self-sufficient composting

Large scale composting requires a large area and generally must be located a long way from collection points. In addition, methane - a greenhouse gas - is often lost to the atmosphere in the process.

The Environmental Biotechnology CRC (EBCRC), together Organic Resource Technologies (ORT) and Murdoch University, is using biotechnology in a $1.3m project to enhance a process that can convert large amounts of organic waste to compost more efficiently.

"This system reduces landfill and the time needed to create compost, is energy efficient and does not smell," said EBCRC researcher, Lee Walker, based at Murdoch University.

"The system allows methane to be collected and used to generate electricity to run the whole process, making it self-sufficient," he said.

Advanced biotechnology is being applied to a process called DiCOM, developed by ORT. The process operates within specially designed sealed tanks that allow control over all environmental factors, with each tank able to take the organic fraction from around 1000 tonnes of municipal solid waste every three weeks.

Tom Rudas from ORT explains that biotechnologists can make a big difference to composting processes: "Advanced biotechnolgies are allowing us to further investigate how the microorganisms involved in our composting process work."

Since the process is compact and lacks offensive odours, existing municipal sites can use this technology to process the organic waste they receive and produce stable compost, consistent with Australian standards, suitable for agricultural and amenities use, all for around the same cost as current practices.

In the process, air is pumped into the tank for the first five days. The airflow into the tank is then stopped so different bacteria can work in an oxygen-free environment for the next seven days.

Methane is produced during this stage and can be used to generate electricity. Air is pumped in again during the last seven days to produce garden-quality compost.