In a comprehensive life cycle analysis, the treatment of sewage sludge through hydrothermal carbonization (HTC) has achieved the best results compared to other technologies.
In an increasing number of countries, the incineration of sewage sludge is being considered a safe disposal pathway. Decisions regarding future pre-treatment technologies are currently being made. The life cycle assessment (LCA) is of particular interest here, as it provides comprehensive information about relevant impacts.
According to a recent study in the “Cleaner Environmental Systems” journal, the data from HTC is compared with those from Pyrolysis and conventional mono-incineration of sewage sludge.
With specific net-negative greenhouse gas emissions of -71.4 g CO2-eq for 1 kg of digested sewage sludge (5% dry matter), HTC achieved the best results of all scenarios with sludge incineration. In contrast, conventional mono-incineration technology is associated with approximately + 10 g CO2-eq of greenhouse gas emissions.
Credits: Gievers, F., Mainardis, M., Catenacci, A., Loewen, A., Nelles, M., Life cycle assessment of biochar and hydrochar derived from sewage sludge: Material or energy utilization?, Cleaner Environmental Systems, https://doi.org/10.1016/j.cesys.2024.100254.