Improvement of Anaerobic Digestion of Lignocellulosic Biomass by Hydrothermal Pretreatment

Abstract

Lignocellulosic biomass, comprising of cellulose, hemicellulose, and lignin, is a difficult-to-degrade substrate when subjected to anaerobic digestion. Hydrothermal pretreatment of lignocellulosic biomass could enhance the process performance by increasing the generation of methane, hydrogen, and bioethanol. The recalcitrants (furfurals, and 5-HMF) could be formed at high temperatures during hydrothermal pretreatment of lignocellulosic biomass, which may hinder the process performance. However, the detoxification process involving the use of genetically engineered microbes may be a promising option to reduce the toxic effects of inhibitors. The key challenge lies in the scaleup of the hydrothermal process, mainly due to necessity of upholding high temperature in sizeable reactors, which may demand high capital and operational costs. Thus, more efforts should be towards the techno-economic feasibility of hydrothermal pre-treatment at full scale.

Anaerobic Digestion for Producing Renewable Energy—The Evolution of This Technology in a New Uncertain Scenario

“…Recalcitrant compounds, such as furfurals, could also be formed at high temperatures during hydrothermal pretreatment, which may hinder the performance of the subsequent biological process [ 81 ]. Another important fact that should also be evaluated is the high energy demand of these pre-treatment units and the high capital investment.…”

Editorial of the Special Issue “Anaerobic Co-Digestion of Lignocellulosic Wastes”

“…The effect of enzymatic (cellulase) pretreatment on particulate disintegration of this waste was studied by Tassew et al [10]. Moreover, the review by Ahmed et al [11] offers an in-depth insight into hydrothermal pretreatment with a section dedicated to inhibitors formed by the delignification process (mainly furfural and 5-HMF) and strategies to overcome it.…”

Liquid Hot Water Pretreatment of Lignocellulosic Biomass at Lab and Pilot Scale

“…Pretreatment of biomass is one of the key technologies in bio-based industry, and it has been extensively studied due to the complexity of the internal structure of the lignocellulosic material [3,4]. Different methods have been applied, which usually focus on enhancement of the availability of carbohydrates for subsequent enzymatic hydrolysis and fermentation to bio-fuels and bio-based chemicals [5].…”