Wet organic waste treatment via hydrothermal processing: A critical review

There are several recent reviews published in the literature on hydrothermal carbonization, liquefaction and supercritical water gasification of lignocellulosic biomass and algae. The potential of hydrochar, bio-oil or synthesis gas production and applications have also been reviewed individually. The comprehensive review on the hydrothermal treatment of wet wastes (such as municipal solid waste, food waste, sewage sludge, algae) covering carbonization, liquefaction and supercritical water gasification, however, is missing in the literature which formed the basis of the current review paper. The current paper critically reviews the literature around the full spectrum of hydrothermal treatment for wet wastes and establishes a good comparison of the different hydrothermal treatment options for managing wet waste streams. Also, the role of catalysts as well as synthesis of catalysts using hydrothermal treatment of biomass has been critically reviewed. For the first time, efforts have also been made to summarize findings on modelling works as well as techno-economic assessments in the area of hydrothermal treatments of wet wastes. The study concludes with key findings, knowledge gaps and future recommendations to improve the productivity of hydrothermal treatment of wet wastes, helping improve the commercial viability and environmental sustainability. (C) 2021 Published by Elsevier Ltd.

Automated summary

This paper reviews recent literature on hydrothermal carbonization, liquefaction and supercritical water gasification of lignocellulosic biomass and algae, as well as the production and applications of hydrochar, bio-oil, and synthesis gas. It also critically examines the comprehensive review of hydrothermal treatment for wet wastes, including municipal solid waste, food waste, sewage sludge, and algae, while establishing a comparison of different treatment options. Additionally, the study delves into the role of catalysts and the synthesis of catalysts using hydrothermal treatment of biomass, and summarizes findings on modeling works and techno-economic assessments in this area for the first time.