SUEZ and PYREG launch an innovative integrated pyrocarbonisation solution to produce biochar from sewage sludge
Approximately 340 million tonnes of industrial and agricultural effluents, including municipal wastewater sludge, are generated annually in France. The effective management, treatment, and valorisation of these effluents represent an increasing environmental challenge.
SUEZ and PYREG have developed the Pyrolis® S2B pyrocarbonisation process, which integrates drying and pyrolysis of organic waste within a single unit, enabling the transformation of dewatered sludge into biochar. This technology, which can be adapted to all types of infrastructure, significantly reduces the volume of waste derived from municipal and industrial wastewater while permanently sequestering the CO₂ contained within these residues.
An integrated, autothermal, compact, and modular process
Dewatered sludge is initially dried using a low-energy technology developed by SUEZ to achieve 90 % dry solids content. The dried sludge is then fed into the PYREG reactor technology where it undergoes pyrolysis—the heating of organic material to approximately 600 °C in a low-oxygen environment. This produces a stable, carbon-rich biochar that is free of PFAS, and a hydrocarbon-rich pyrolysis gas.
The pyrolysis gas is subsequently fully oxidised at temperatures exceeding 950 °C, generating heat to sustain both the low-energy drying stage and the pyrolysis itself, thus optimising the plant’s overall energy efficiency. High-temperature oxidation also destroys any PFAS that may be present in the pyrolysis gas.
High-value biochar
Biochar produced via the Pyrolis® S2B process is recognised by the IPCC as an effective climate change mitigation tool due to its capacity for stable carbon sequestration.
It also serves as a soil amendment, rich in phosphorus and free from contaminants such as PFAS, microplastics, dioxins, and pharmaceutical residues. This biochar enhances nutrient and water retention, aeration, drainage, and microbial activity in soils. It promotes soil regeneration, improves fertiliser efficiency, and increases agricultural yields—offering significant benefits to the farming sector.
Moreover, it is a valuable additive in the construction industry. Incorporated into concrete, cement, or asphalt, it enhances material performance while substantially lowering their carbon footprint. The durable carbon sequestration facilitated by biochar further qualifies it for inclusion in carbon credit schemes.