The Onunda technology is designed to process raw sewage sludge as an alternative to traditional wastewater treatment processes, allowing customers to increase or replace existing capacity of their wastewater treatment facilities with our next-generation technology. We see the current situation as an opportunity for innovation to turn waste into worth.

recycling icon

Hydrothermal Carbonization (HTC)

Onunda has developed a unique integrated method of treating sewage sludge and biosolids by combining hydrothermal technology and gasification. The application of high temperature and pressure breaks down the organic material into its constituents, recovering valuable nutrients and eliminating harmful chemicals and pathogens in the process.

This novel approach, combined with sludge dewatering technologies, produces energy-rich hydrochar which is subsequently converted into clean energy using our proven gasification technology.

Operative inspecting a gauge
Aerial shot of a tractor in a field

Water Removal

The dewatering process produces a clean High Nutrient Liquid that is free from microplastics and forever chemicals, and has been produced without any fossil fuels. The High Nutrient Liquid has multiple applications as a clean fertiliser or can also be used directly as a feedstock to boost biogas production.


Within the gasifier, we use the hydrochar to produce syngas which is then used to both heat and energise the entire system meaning that the entire process does not require any external sources of energy or fossil fuels to process, dry and clean the sewage. The system produces excess syngas, which is then used to produce clean energy which can be extracted to the Grid.

Electricity pylon

The benefits

Environmental stewardship at our core

Onunda is a beacon of environmental responsibility, providing cutting-edge technology to eliminate sewage sludge discharge and convert it into clean energy and nutrient-rich fertiliser. It addresses challenges facing wastewater treatment plants in dealing with the solids produced from traditional biological processes.

Swirling water going down a plug Planet Earth

Onunda technology is versatile in its application to both new and existing wastewater treatment facilities, as well as various domestic, industrial, and agricultural organic wastes.

01 - Integration with existing Sewage Treatment facilities

Onunda can be immediately implemented at all existing traditional wastewater treatment facilities as an additional process to treat all biosolid material currently being discharged to land.

02 - New Sewage Treatment Solution

Onunda is the next generation of innovative wastewater treatment and can be deployed whenever new investments are being made in new wastewater treatment capacity thereby ensuring that future sewage works benefit from the full extraction of value, nutrients and power with no waste material being returned to land.

03 - Organic Farm Waste Streams

Onunda technology can be deployed to treat waste streams from farming and agricultural activities ensuring all energy, nutrients and value are captured and utilised.

04 - Industrial Food Waste Applications

There are many forms of organic waste streams within the food industry that could readily be treated using Onunda technology to fully extract value and avoid the need for any waste to be disposed of to land.

Nutrient Neutrality Solution

By deploying Onunda technology in all of the above applications we are effectively removing a range of biosolid waste products from the current practice of discharging nutrient rich waste materials to land. The application of Onunda technology is therefore an ideal technology application to secure Nutrient Neutrality offset credits to unlock developments which are currently locked out due to their impacts to the current nutrient balance. Onunda is the ideal technology partner to unlock Nutrient Neutrality barriers.