Abstract Hydrothermal liquefaction (HTL) is a thermochemical conversion technology that shows promising commercial potential for the production of biocrude oil from wet biomass. However, the inevitable production of the hydrothermal liquefaction aqueous phase (HTL-AP) acts as a double-edged sword: it is considered a waste stream that without additional treatment clouds the future scale-up prospects of HTL technology; on the other hand, it also offers potential as an untapped nutrient and energy resource that could be valorized. As more researchers turn to liquefaction as a means of producing renewable fuel, there is a growing need to better understand HTL-AP from a variety of vantage points. Specifically, the HTL-AP chemical composition, conversion pathways, energy valorization potential, and the interconnection of HTL-AP conversion with biofuel production technology are particularly worthy of investigation. This paper extensively reviews the impact of HTL conditions and the feedstock composition on the energy and elemental distribution of process outputs with specific emphasis on the HTL-AP. Moreover, this paper also compares and contrasts the current state of value-added products separation along with biological (biomass cultivation, anaerobic fermentation, and bioelectrochemical systems) and thermochemical (gasification and HTL) pathways to valorize HTL-AP. Furthermore, life cycle analysis (LCA) and techno-economic assessments (TEA) are performed to appraise the environmental sustainability and economic implications of these different valorization techniques. Finally, perspectives and challenges are presented and the integration approaches of HTL-AP valorization pathways with HTL and biorefining are explored.

中文翻译：

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热液液化水相的价值化：通往商业可行性的途径

摘要 水热液化 (HTL) 是一种热化学转化技术，显示出从湿生物质生产生物原油的商业潜力。然而，水热液化水相 (HTL-AP) 的不可避免的产生就像一把双刃剑：它被认为是一种废物流，如果没有额外的处理，它会影响 HTL 技术的未来规模化前景；另一方面，它也提供了作为未开发的营养和能源资源的潜力，可以加以利用。随着越来越多的研究人员将液化作为生产可再生燃料的一种手段，越来越需要从各种有利的角度更好地了解 HTL-AP。具体来说，HTL-AP 的化学成分、转化途径、能量增值潜力、以及 HTL-AP 转化与生物燃料生产技术的互连尤其值得研究。本文广泛回顾了 HTL 条件和原料组成对过程输出的能量和元素分布的影响，特别强调了 HTL-AP。此外，本文还比较和对比了增值产品分离的现状以及生物（生物质培养、厌氧发酵和生物电化学系统）和热化学（气化和 HTL）途径，以提高 HTL-AP 的价值。此外，还进行了生命周期分析 (LCA) 和技术经济评估 (TEA)，以评估这些不同增值技术的环境可持续性和经济影响。最后，