Hydrothermal treatment of cow manure (The Netherlands)

This study investigates the impact of hydrothermal treatment on cow manure, as a simulant of faecal sludge in on-site sanitation systems, within a temperature range of 100°C to 260°C, using 40°C intervals to understand the fate of nutrients and to evaluate the suitability of the treatment product for agricultural land application and bioenergy recovery. Detailed characterisation, including initial and post-treatment analyses of the solid (hydrochar) and liquid (process water/HTCL) phases, was carried out. Key findings reveal that thermal hydrolysis reactions in cow manure are mainly above 140°C, Highlighting the critical temperature range for these reactions higher than 140°C. Furthermore, a substantial improvement in dewaterability above is observed at 180°C. Notably, the temperature range specific to hydrothermal carbonisation shows a superior capacity to immobilise nutrients in solid phases, ensuring the safe application of hydrochar as a nutrient-enriched soil conditioner in agriculture. This research reveals the potential of hydrothermal treatment in proficient organic waste management, with implications for sustainable waste practices, soil amendment, and clean energy generation, connecting the gap between waste management and environmental sustainability. This research will further enhance the understanding and applicability of this high moisture waste treatment method, recognizing the need for comprehensive analysis of initial compositions and potential compound formation to ensure safe and effective faecal sludge treatment.