University Of Tehran Press Pollution 2383-451X 11 2 2025 02 01 Optimization and Modeling of Retention Time and Temperature Parameters in the Hydrothermal Carbonization Process of Sewage Sludge 538 549 99870 10.22059/poll.2024.383262.2587 EN Reza Ghasemzadeh Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Tehran, Iran 0000-0003-0826-1582 Abolghasem Pazoki Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Tehran, Iran 0000-0003-1733-3365 Sanaz Tajziehchi Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Tehran, Iran Setareh Ahmadi Department of Computer Engineering, Faculty of Electrical and Computer Engineering, Technical and Vocational University (TVU), Tehran, Iran Alireza Davami Department of Environmental Engineering, Graduate Faculty of Environment, University of Tehran, Tehran, Iran Journal Article 2024 10 05 The sustainable management of wastewater treatment plant sludge is a significant challenge in urban waste management. Hydrothermal carbonization (HTC) offers a promising approach by converting sludge into valuable products like hydrochar. This study hypothesized that optimizing HTC parameters could enhance hydrochar production while improving energy recovery. The objectives were to model and optimize the effects of temperature (150-250 °C) and retention time (20-60 min) on hydrochar yield (HY), higher heating value (HHV), and energy yield (EY). Using the Response Surface Methodology with Central Composite Design, three quadratic models were developed to analyze these parameters' interactions and identify optimal process conditions. Experimental results indicated maximum HY (59.96%) at 160.31 °C and 28.14 min, maximum HHV (26.88 MJ/kg) at 246.45 °C and 60 min, and maximum EY (82.18%) at 207.78 °C and 34.28 min. These findings highlight HTC's potential for efficient sludge management. Future research could focus on the environmental implications and scaling HTC technology for broader applications. https://jpoll.ut.ac.ir/article_99870_1ebe2acfd537c2d9f76c20d242db1bd5.pdf