Injecting new life into biosolids in Victoria




At South East Water, we don’t see wastewater as waste. That’s why we recycle it for reuse, and are now investigating new ways to use biosolids – a by-product of the wastewater treatment process.

Farmers can use this nutrient-rich fertiliser to maintain soils and stimulate plant growth, which increases their productivity. We currently produce biosolids for agricultural use at our 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, the project will trial soil injection of biosolids in liquid form to improve soil structure, fertility and function at our Longwarry Water Recycling Plant.

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

We celebrated the success of the project so far with our partners by hosting a biosolids field day with more than 100 industry professionals and researchers at the plant.

EPA Victoria approved our request to undertake the trial through its research, development and demonstration (RD&D) pathway. Water organisations have used liquid biosolids in Australia since 1998, but all applications so far have been limited to New South Wales.

University of Newcastle environmental remediation researcher and one of the project investigators, Dr Balaji Seshadri, said optimising the use of biosolids will result in high value products that can 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.” Said Dr Seshadri.

The current process for producing biosolids in Victoria involves a long treatment process to make sure the product meets treatment grade T1 – the only type of biosolids deemed safe for unrestricted use as fertiliser on farms. This includes storing the product for a minimum of three years before it’s used.

Soil CRC CEO Dr Michael Crawford believes this project is 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.”

“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.” Said Dr Crawford.

We hope to prove that using biosolids in liquid form (known as T2 or T3 treatment grade) is appropriate for use on agricultural crops. This would permit time and cost efficiencies through bypassing conventional drying and stockpiling processes.” Said South East Water’s Senior Research and Planning Scientist, Dr Aravind Surapaneni.

“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.” Said Dr Surapaneni.

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


South East Water

South East Water delivers water, sewerage and recycled water services to 1.79 million people in Melbourne’s south east. Our service area borders more than 270 kilometres of coastline and covers a land area of 3,640 square kilometres from Port Melbourne to Portsea and approximately 30 kilometres east of Pakenham.

To help create a better world for our customers, we’re always thinking and acting ahead to ensure we can always support our customers with reliable and affordable water services.

Soil CRC

The Soil CRC is the biggest collaborative soil research effort in Australia’s history. It brings together 40 partners from universities, farmers groups, state agencies and industry, including South East Water, with an aim to enable to help farmers to increase their productivity and profitability by providing them with knowledge and tools to improve the performance of their soils.