Sludge experience joins export list

4 January 2005.

Sludge experience joins export list

Kiwi "know how² has long been a strong New Zealand export and now our experience in sludge management has won the support of the Asia 2000 Foundation for a collaborative research project in China.

Lincoln University microbiologist Dr Mike Noonan has been awarded an Asia 2000 Foundation Higher Education Exchange Programme (HEEP) grant to work collaboratively with the Environmental Engineering School at the South West University of Science and Technology in Mianyang, Sichuan province, China, on the sustainable use of sludge from municipal and industrial waste.

Asia 2000 Foundation HEEP grants initiate or support tertiary exchanges, placements or collaborative research between New Zealand and partner institutions in Asia.

"Sewage disposal is a major problem in populous countries,² says Dr Noonan, "and while treated water from sewage can be discharged into rivers and elsewhere, the solid part of the waste - the sludge - is more difficult to use in a sustainable way.

"If the waste is industrial in origin it may be high in heavy metals,² says Dr Noonan, "and equally municipal sludge may contain harmful viruses, bacteria and small animals. This means it cannot be applied to land used for the production of food without further treatment.

"While burying and burning are possible treatment options, both these methods waste a potentially useful resource.

"Increasing the temperature of the sludge by composting is a method used in many parts of the world to destroy the harmful organisms and make the material more suitable as a soil conditioner or fertiliser. However, for composting to be a success, oxygen from the air needs to be supplied to the microbes responsible for the decomposition. Because of the concentrated and viscous nature of sludge, satisfactory aeration is often a problem so it is frequently mixed with more open material to facilitate the process.

"Much rice straw is burnt in the area around Mianyang and we want to investigate if this would be a suitable material to mix with the sludge to make good compost.²

The Asia 2000 Foundation grant gives Dr Noonan and Chinese researchers from the South West University of Science and Technology (SWUST) the opportunity to cooperate on this compost research.

"The local farmers run very small scale holdings and the land is in continuous cultivation," says Dr Noonan. "The compost may help them maintain the fertility and structure of their soil.

"The presence of heavy metals in sludge can be a problem. The best way to deal with them is to make sure they are taken out at the factory end of the process."

A staff member from the South West University of Science and Technology will come to New Zealand as part of the Asia 2000 Foundation grant and among other projects he will study the way trade waste inspectors in New Zealand ensure that heavy metals, especially from factories, do not find their way into sewage.

Another staff member, Guangming Jiang, is already at Lincoln University completing a masters degree under the supervision of Dr Noonan, supported by the New Zealand Agency for International Development.

"He is doing excellent work to try to stop harmful microbes from animal manures being washed down into groundwater," says Dr Noonan.

Two senior staff members from SWUST visited Lincoln University in 2004 and signed a Memorandum of Understanding between the institutions and in September Dr Noonan visited SWUST for preliminary discussions on the collaborative research project.

"The people I met and the food I ate in Mianyang were both wonderful, so I am very much looking forward to a second visit to get our joint project under way," he says. "China is a country of exciting change."

ENDS

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