Every year, 3.5 million tonnes of treated sewage sludge are spread onto UK farmland, carrying micropollutants that contaminate soil and water. This matters because current methods of handling biosolids—incineration, landfill, or agricultural spreading—create serious environmental and public health risks. Globally, 22% of biosolids are incinerated and 17% go to landfill, producing 88 million tonnes of CO₂-equivalent emissions annually. Meanwhile, 0.5–3% of the biosolids applied to farmland contain micropollutants, which can accumulate in crops and water systems. Stricter regulations are likely, raising costs for water utilities and their customers. Onunda, a UK-based SME, is developing a new valorisation process that treats biosolids inside sewage works. If successful, the technology would remove 97% of micropollutants from biosolids, increase energy output by 82% through syngas production, and cut CO₂-equivalent emissions by 80% for utilities that currently incinerate or landfill their waste. Farmers would receive cleaner fertiliser, and utilities could reduce operational costs by decoupling from grid power. This is a practical engineering solution aimed at transforming a hidden but costly waste stream into a cleaner resource.
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Onunda is a UK-based biosolids and bioresources management SME led by Tom Samson (CEO/project lead), James Meyer (CTO/technical lead), Dr Victor Aladeokin (chemical engineer) and Lee Wise (mechanical engineer). Each year, 1.3% of farmland in the UK is fertilised with 3.5 Mt of recycled biosolids, providing nutrients worth approximately £60M. In 2024, global biosolids production was 33 Mt and is expected to reach 91 Mt/year by 2050, at a growth rate of 3.8%. However, 0.5--3% of the biosolids applied to the farmland contain micropollutants. Globally, 22% of biosolids are incinerated, and 17% are sent to landfills, contributing 88 Mt/year of CO2-equivalent emissions. Current biosolids disposal methods create public and environmental health risks and increase public pressure on water utilities. Continued micropollutant contamination will lead to stricter regulations, higher costs for water utilities and customers, and significant environmental degradation affecting stakeholders globally. Onunda will address this issue by developing a technologically innovative valorisation process to eradicate the harmful environmental impacts of treating and disposing of biosolids and bioresources. The primary impact of integrating Onunda's technology within sewage works will be to increase energy output by 82% and remove 97% of micropollutants in biosolids. By integrating Onunda's technology, water utilities currently incinerating or sending biosolids to landfills can reduce CO2-equivalent emissions by 80%. Utilities that use agricultural landbanks can remove 97% of micropollutants and provide farmers with a cleaner fertiliser. Syngas produced by Onunda's technology can increase energy outputs by 82%, saving OPEX and allowing utilities to decouple from grid power.
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