The future landscape of biosolids reuse

Biosolids have been a flashpoint for wastewater treatment plants, with new regulations forcing them to rethink their approach. Mono-incineration could be an alternative option.

Biosolids have been a flashpoint for wastewater treatment plants, with new regulations forcing them to rethink their approach. Mono-incineration could be an alternative option.

Up to 400,000 dry tonnes per annum of biosolids are produced from Australian and New Zealand sewage treatment plants. There needs to be a serious discussion about what is done with those biosolids, according to John Koumoukelis, CEO of Hydroflux Epco.

Across the globe, the last decade has seen a trend toward diverting biosolids from landfills. Trends have also discouraged some countries from using biosolids for agricultural purposes. In addition, governments have been considering alternative treatments to address public concerns over pollutants such as microplastics and perfluoroalkyl and polyfluoroalkyl substances (PFAS).

In 2017, Germany banned the agricultural use of biosolids. This led to the construction of numerous advanced biosolids facilities, most of which are based on mono-incineration.

Mono-incineration is new process for biosolids

Mono-incineration is a process that uses biosolids derived from sewage as a fuel source to generate power. This powers the incineration plants and returns energy to the local domestic grid.

Other markets have looked at alternative solutions, such as hydrolysis upstream of biosolids digestion to enhance biogas/electricity production. They ultimately produce a class A biosolid that can be reused without restriction.

“As the Australian and New Zealand agent for HUBER Technology, we are fortunate to have access to HUBER’s global expertise in biosolids treatment. It can play a key role in generating renewable electricity by unlocking its energy potential,” said Koumoukelis.

Sludge2Energy offers biosolid technology

Sludge2Energy has built up its reference base after ten years of operating its first mono-incineration plant in Straubing, Germany. It now has six facilities under construction. Its project at Hanover-Lahe began construction in February 2021 and will start regular operation in early 2023. On completion, it will process 130,000 tonnes per annum of biosolids that provide power for up to 5000 households.

Mono-incineration and other similar processes are topics discussed among many Australian water authorities. Lessons learnt in the design and operation of the drying step are something Hydroflux can offer in addition to the Sludge2Energy process itself.

“Partial drying, which produces biosolids with 40 per cent dry solids, can be an ideal intermediate step that bridges the gap between business-as-usual practice and planning for resilience,” said Koumoukelis.

HUBER’s biosolids drying technology includes RotaDry Disc Dryers, BT Belt Dryers, and Solstice Solar Dryers. These technologies rely on a heat source, typically a waste gas produced within the treatment plant that can be reused. Solstice relies on renewable solar energy as the heat source.

Key features of drying include reduced transport costs and associated carbon emissions. They also have the option for class A biosolids for unrestricted beneficial reuse and future planning for further advanced treatment.


HUBER is headquartered in Berching, Germany. It is a globally active company in water, wastewater, and sludge treatment. It is a joint venture member of Sludge2Energy.

Hydroflux is HUBER’s exclusive Australian, New Zealand, Papua New Guinea, and Pacific Islands representative.

About Hydroflux

The Hydroflux Group consist of eleven specialist companies that aim to deliver the highest level of engineering and scientific know-how to the emerging issues of sustainability, climate adaptation and environmental protection with a specific focus on water and wastewater.

The Group employs over 100 staff and operates throughout Australia, New Zealand, and the Pacific Islands, with office locations in Sydney, Melbourne, Brisbane, Perth, Auckland, Suva, and Portsmouth.

Contact Hydroflux at (or for more information.

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