Biosolids a by-product well worth saving and reusing

Biosolids a by-product worth saving and reusing

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Project could change guidelines on liquid injection in soils of biosolids in Victoria.

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South East Water is investigating ways of using biosolids, a by-product of its wastewater recycling processes.

Farmers would benefit from nutrient-rich fertiliser to maintain soils and stimulate plant growth, which increased their productivity.

SEW was already producing biosolids for agricultural use at its Boneo, Somers, Pakenham and Blind Bight Water recycling plants.

Supported by the Soil Cooperative Research Centre (Soil CRC) and partnering with the University of Newcastle, NSW, the project will trial soil injection of biosolids in liquid form to improve soil structure, fertility and function at its Longwarry Water Recycling Plant.

The trial has so far seen a crop of summer forage sorghum produced from liquid injection of biosolids under dryland conditions.

A field day was held recently that attracted more than 100 industry professionals and researchers at the plant.

EPA Victoria approved SEW's request to undertake the trial through its research, development and demonstration (RD&D) pathway.

University of Newcastle environmental remediation researcher and one of the project investigators, Dr Balaji Seshadri, said optimising the use of biosolids would resulted in high value products that could enhance agricultural productivity and soil health.

"Delivering nutrients and organic matter in biosolids to the root zone via liquid injection is one novel approach we're exploring through this joint trial that will ultimately benefit Australia's farming community." Dr Seshadri said.

The current process for producing biosolids in Victoria involved a long treatment process to make sure the product met treatment grade T1 - the only type of biosolids deemed safe for unrestricted use as fertiliser on farms. This included storing the product for a minimum of three years before it's used.

Soil CRC CEO Dr Michael Crawford said the new project was vital.

"In addition to addressing an important issue for the water sector, it provides scientists and farmers with an understanding of how the addition of organic matter and nutrients to the subsoil can improve soil productivity and ultimately, farmer profitability," Dr Crawford said.

"The Soil CRC provides the opportunity for effective collaboration between industry and science as well as a pathway to adoption of new soil management technologies by farmers." he said.

South East Water's Senior Research and Planning Scientist, Dr Aravind Surapaneni said it was hoped the project would prove that using biosolids in liquid form (known as T2 or T3 treatment grade) was appropriate for use on agricultural crops.

"This would permit time and cost efficiencies through bypassing conventional drying and stockpiling processes," Dr Surapaneni said.

"By undertaking this trial we can assess the impact of using T3 grade liquid biosolids on crops, as well as identifying any potential risks of using this by-product." Dr Surapaneni said.

If successful, the project had the potential to influence EPA guidelines on liquid injection of T3 grade biosolids in Victoria, which would be great news for water recycling plants, local farmers and their crops, he said.

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