22 November 1998

Minister to open UQ rubbish pilot plant

A University of Queensland project harnessing methane from solid waste stands to revolutionise Australia's future rubbish management.

Technology developed by the Chemical Engineering Department cuts rubbish decomposition time to two months - a process normally requiring at least 40 years in conventional landfills.

The Department has constructed a pilot plant accepting waste from 100 Brisbane households, at the University's Veterinary Science Farm at Pinjarra Hills.

Queensland Mines and Energy Minister Tony McGrady will open the plant on Tuesday, December 8, at 4pm.

The research is headed by Department Associate Professor Victor Rudolph with the assistance of postdoctoral research fellow Dr Sandeeg Chugh and undergraduate student David Reinke.

The plant, consisting of two rubber-lined, steel tanks (one 15-cubic-metres and the other 10-cubic-metres in volume), heaters and pumps, will harness methane and carbon dioxide from rubbish for use in either gas-powered electrical generators or as the liquid fuel methanol to power state-of-the-art cars.

One-third of the weight of waste evaporates in the form of methane and carbon dioxide. These gases are emitted by the microorganisms breaking down the rubbish. The researchers plan to build a miniature methanol plant to convert the gases into the liquid fuel.

The main plant operates by re-circulating leachate (micro-organism-containing moisture) from one tank (containing old, micro-organism-rich waste such as sludge) to the other (containing fresh waste) once a day for a week.

Dr Rudolph said this allowed micro-organisms and moisture, the two essential ingredients for rubbish degradation, to spread evenly throughout the fresh waste.

After the first week, the fresh waste tank contains enough micro-organisms to continue the decomposition process unaided. Two months later, one-third of the mass has been harnessed as methane and carbon dioxide.

The remainder consists of a black, compost-like substance and the non-degradable material in the rubbish such as glass, plastic and stones.

For unsorted waste, this non-degradable material goes to landfill. Dr Rudolph said if sorted waste was used, there would be no unusable element at the end of the process since the black compost material could be used as a soil conditioner.

He said there were many advantages in processing rubbish in the tanks rather than the present system of burying rubbish at sanitary landfills.

"We can harness the energy from the methane therefore removing a harmful Greenhouse gas from the environment. Most rubbish can also be broken down in a matter of a few months rather than the 40 or so years it takes using landfill," he said.

The tank system also eliminated smells and mess associated with current landfill methods, he said.

The initial phase of this research was supported by the University's node of the Co-operative Research Centre for Waste Management and Pollution Control and began five years ago.

The opening ceremony will be held in the Virology Seminar Room at the Veterinary Science Farm, 2436 Moggill Road, Pinjarra Hills.

For more information, contact Dr Rudolph (telephone 07 3365 3616).