New insights into the hydrothermal carbonization process of sewage sludge: A reactive molecular dynamics study

Abstract

In this work, reactive molecular dynamics simulations using the ReaxFF force field were performed to investigate the hydrothermal carbonization (HTC) process of sewage sludge. The focus was on the reaction mechanism, the effect of water content and temperature on the formation of different products. The results showed that temperature was the most important factor controlling the HTC process, with higher temperatures leading to more rapid carbonization reactions and lower H/C and O/C ratios in the hydrochar product. The estimated activation energy of the HTC process was in the range of 126–169 kJ/mol, depending on the water content. The H/C and O/C ratios of the hydochar product obtained from the simulation were in excellent agreement with experimental data. Overall, this work provides valuable new insights into the reaction mechanism and key factors influencing the HTC process of sewage sludge.