# Recent Advances in Hydrothermal Oxidation Technology for Sludge Treatment
## 3 Conclusions and Prospect
This raises the question of whether it is possible to regulate the sludge treatment process to produce a single type of carboxylic acid. For example, if only acetic acid were produced, it could be entirely used as a carbon source. Moreover, the detection technology for different acids in the sludge effluent requires further optimization. Advanced chromatographic techniques could be employed to distinguish and separate these acids more effectively. (6) Cost reduction: Successfully treated sludge products can be utilized for resource recovery, generating economic benefits and reducing overall costs. Additionally, using inexpensive oxidants and catalysts, as well as developing new technologies to enhance treatment efficiency, can further lower costs. (7) Diversifying applications: Currently, the applications of treated sludge are somewhat limited, mainly focused on construction materials or soil conditioners. Further exploration is needed in areas such as electricity generation, hydrogen production, and methane production. Expanding the applications of sludge products and forming a comprehensive industrial chain would maximize the utility of treated sludge. Additionally, equipment innovation and improvement will be a key focus of future research to enhance stability, reliability, and cost-efficiency. Looking ahead, hydrothermal oxidation technology has the potential to play an increasingly important role in sludge treatment. As the technology continues to evolve, costs will decrease, and efficiency will improve. Furthermore, combining this technology with other advanced methods could open new possibilities for sludge treatment. In the near future, hydrothermal oxidation is expected to become a mainstream technology in sludge management, contributing significantly to environmental protection and sustainable development. Conceptualization, H.Y. and Y.L. ; methodology, H.Y., Y.L. and N.G. ; software, Z.P. and W.P. ; validation, J.W., L.W. and B.Z. ; formal analysis, B.Z. and Y.Z. ; investigation, J.W. and Y.Z. ; resources, L.W. ; writing--original draft preparation, H.Y., Y.L. and N.G. ; writing--review and editing, W.P., H.Y. and H.W. ; visualization, Z.P. ; supervision, H.Y. ; project administration, H.W. ; funding acquisition, H.Y. and H.W. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (No. 52370127), Young Elite Scientists Sponsorship Program by China Association for Science and Technology (No. 2022 QNRC001), Project LJ222410151015, supported by Fundamental Research Funds of higher education Department of Liaoning Province (Program for Liaoning Innovative Research Team in University), and Fundamental Research Funds for the Central Universities (No. 3132023518). This work was financially supported by the National Key R&D Program of China (2023 YFE0101000) and Innovation Research Fund of Dalian Institute of Chemical Physics (DICP I202320). The authors confirm that the data supporting the findings of this study are available from the authors upon reasonable request. Author [PERSON] and [PERSON] were employed by the company Hangzhou Sunrise Environment Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.