SCU research used to develop new sewage solution

Ground-breaking technology developed by Southern Cross University (SCU) researchers to treat acid mine drainage and acid sulphate soils has been further developed and utilised by Virotec International to invent a chemical treatment system to improve the quality of treated sewage effluent and reduce odours.

This new technology has been put to use by the Richmond Valley Council in Northern New South Wales.

Virotec International, which has exclusive rights to the technology, won a contract to improve the quality of effluent from the Evans Head Sewage Treatment Plant in October 2003.

Dr Malcolm Clark, a senior research fellow at Southern Cross University, together with Professor Dave McConchie, developed a technology which uses modified residue from the bauxite (the principle ore in aluminium) refining process to treat mining wastes.

This modification converts a highly caustic and restricted waste material into a near-neutral red earthy product, which has a good acid neutralising capacity an excellent metal binding capacity, and good phosphorous binding capacity. Although the material is fine grained, it also has an excellent capacity to agglomerate suspended material in waters and settle these particles, allowing clarification of turbid waters.

Dr Clark said the residue could be added to sewage effluents to reduce the level of phosphorous and therefore reduce the chance of blue green algae. At the Evans Head Sewage Treatment Plant it is being used primarily to remove BOD and suspended solids from sewage.

“One of the things associated with sewage effluent discharge is the potential for blue green algae. By removing the phosphorous from the system we limit the ability of blue green algae to grow,” Dr Clark said.

“It’s using a modified waste material for beneficial purposes, which is all part of this idea of sustainability. We are looking at someone’s waste and using it as a raw material for something else. One of the largest bauxite refineries is at Gladstone and they produce 8000 tonnes a day of the residue.”

Dr Clark said the residue could greatly improve the quality of the effluent, as well as the left-over sludge. Another major benefit was its ability to reduce the odour from sewage treatment plants.

“There are certainly a large number of applications in Australia and around the world and the treatment of sewage and waste water is just one of those.”

He said blue green algae was potentially a major problem in Australian waterways and this could provide a cost-effective solution, by reducing phosphorous from sewage discharge waters.

Richmond Valley Council manager of strategic planning, Mr Ray Medhurst, said there were plans to replace the Evans Head Sewage Treatment Plant, but that would not happen for another two years.

“We are putting out higher levels of phosphorous and nutrients than we would like. There was enough evidence that showed we really needed to do something. Council was looking at options that would give us more capacity and also pick up the quality in the short term,” Mr Medhurst said.

After a review of the options two other methods were trialled over a period of months,
but both showed little results.

“Then we got Virotec in and we have had some fairly promising results.”

Mr Medhurst said the technology would be useful in councils throughout Australia, many of which had older style treatment plants.

Virotec International executive chairman, Mr Brian Sheeran, said the contract with Richmond Valley Council was the first step into a global market.

“Municipal wastewater treatment must meet the concurrent challenges of providing affordable sanitation, and meeting the water quality requirements for the protection of the aquatic environment. We believe that the ViroSewage Technology is a cost-effective breakthrough that delivers a suite of beneficial outcomes and overcomes universal challenges,” Mr Sheeran said.

Media contact: Brigid Veale, SCU Media Liaison, 66593006 or m. 0439 680 748.