Direct humification of biowaste with hydrothermal technology: A review

Yuchao Shao, Zhihua Li, Yuyang Long, Jun Zhao, Weizhong Huo, Zhangrui Luo, Wenjing Lu*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

1 Citation (Scopus)


Hydrothermal humification of biowaste, in comparison to the traditional coal-based humic acid extraction process, better aligns with the goals of carbon neutrality and sustainability. This article provided a comprehensive review on the current advancements in hydrothermal humification of biowaste. Hydrothermal humic acid (HHA) derived from different biowaste sources was compared, exhibiting significant differences in their hydrophobicity, oxygen-containing functional group content, and structural characteristics. The influence of key parameters, including reaction temperature, residence time, pH and the action of catalysts on HHA yield was analyzed. The pathways through which biowaste and its major components transform into HHA were elucidated. Coal-like hydrochar has shown significant potential for producing HHA through hydrothermal treatment, with HHA selectivity exceeding 65 %. HHA also exhibits promising performance in agriculture and environmental remediation, offering comparable value to commercial humic acid. Future research should concentrate on establishing the correlation between hydrothermal conditions and the efficiency of biowaste humification, thereby facilitating the development of a predictive model for assessing efficiency. Additionally, exploring the application value of hydrothermal-synthesized HHA with diverse chemical characteristics will guide the optimization of hydrothermal conditions and selection of suitable feedstock.

Original languageEnglish
Article number168232
Number of pages12
JournalScience of the Total Environment
Early online date3 Nov 2023
Publication statusPublished - 15 Jan 2024

Scopus Subject Areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

User-Defined Keywords

  • Application potential
  • Biowaste
  • Chemical property
  • Humic acid
  • Hydrothermal humification
  • Hydrothermal parameter


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