Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review

Lignocelluloses are often a major or sometimes the sole components of different waste streams from various industries, forestry, agriculture and municipalities. Hydrolysis of these materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. However, enzymatic hydrolysis of lignocelluloses with no pretreatment is usually not so effective because of high stability of the materials to enzymatic or bacterial attacks. The present work is dedicated to reviewing the methods that have been studied for pretreatment of lignocellulosic wastes for conversion to ethanol or biogas. Effective parameters in pretreatment of lignocelluloses, such as crystallinity, accessible surface area, and protection by lignin and hemicellulose are described first. Then, several pretreatment methods are discussed and their effects on improvement in ethanol and/or biogas production are described. They include milling, irradiation, microwave, steam explosion, ammonia fiber explosion (AFEX), supercritical CO2 and its explosion, alkaline hydrolysis, liquid hot-water pretreatment, organosolv processes, wet oxidation, ozonolysis, dilute- and concentrated-acid hydrolyses, and biological pretreatments.

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Pretreatment of lignocellulosic wastes to improve ethanol and biogas production: a review.

Trends in biotechnological production of fuel ethanol from different feedstocks.

The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and
future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately
30% of the country’s present petroleum consumption. To ensure reasonable confidence in the study results, an effort was made to use relatively conservative assumptions. However, for both agriculture and forestry, the resource potential was not restricted by price. That is, all identified biomass was potentially available, even though some potential feedstock would more than likely be too expensive to actually be economically available.
In addition to updating the 2005 study, this report attempts to address a number of its shortcomings

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U.S. Billion-ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry

Research on lignin deconstruction has recently become the center of interest for scientists and companies worldwide, racing towards harvesting fossil-fuel like aromatic compounds which are so durably put together by plants as products of millions of years of evolution. The natural complexity and high stability of lignin bonds (also as an evolutionary adaptation by plants) makes lignin depolymerization a highly challenging task. Several efforts have been directed towards a more profound understanding of the structure and composition of lignin in order to devise pathways to break down the biopolymer into useful compounds. The present contribution aims to provide an overview of key advances in the field of lignin depolymerisation. Protocols and technologies will be discussed as well as critically evaluated in terms of possibilities and potential for further industrial implementation.

Evaggeli Billa

Papers

Structure and composition of sweet sorghum stalk components

Two-stage acid-catalyzed fractionation of lignocellulosic biomass in aqueous ethanol systems at low temperatures

Investigation of lignins structure in cereal crops by chemical degradation methods

Optimizing multisteps mechanical-chemical fractionation of wheat straw components

Fluorescence analysis of paper pulps