Wet wastes to bioenergy and biochar: A critical review with future perspectives

Jie Li, Lanyu Li, Manu Suvarna, Lanjia Pan, Meisam Tabatabaei, Yong Sik Ok, Xiaonan Wang

Research output: Contribution to journalReview articlepeer-review

53 Citations (Scopus)


The ever-increasing rise in the global population coupled with rapid urbanization demands considerable consumption of fossil fuel, food, and water. This in turn leads to energy depletion, greenhouse gas emissions and wet wastes generation (including food waste, animal manure, and sewage sludge). Conversion of the wet wastes to bioenergy and biochar is a promising approach to mitigate wastes, emissions and energy depletion, and simultaneously promotes sustainability and circular economy. In this study, various conversion technologies for transformation of wet wastes to bioenergy and biochar, including anaerobic digestion, gasification, incineration, hydrothermal carbonization, hydrothermal liquefaction, slow and fast pyrolysis, are comprehensively reviewed. The technological challenges impeding the widespread adoption of these wet waste conversion technologies are critically examined. Eventually, the study presents insightful recommendations for the technological advancements and wider acceptance of these processes by establishing a hierarchy of factors dictating their performance. These include: i) life-cycle assessment of these conversion technologies with the consideration of reactor design and catalyst utilization from lab to plant level; ii) process intensification by integrating one or more of the wet waste conversion technologies for improved performance and sustainability; and iii) emerging machine learning modeling is a promising strategy to aid the product characterization and optimization of system design for the specific to the bioenergy or biochar application.

Original languageEnglish
Article number152921
JournalScience of the Total Environment
Publication statusPublished - 2022 Apr 15

Bibliographical note

Publisher Copyright:
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  • Biological and thermal conversion
  • Carbon sequestration
  • Charcoal
  • Clean energy
  • Sustainable development goals
  • Waste to energy and resource

ASJC Scopus subject areas

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


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