The use of high‐solids loadings (≥ 15% solids, w/w) in the unit operations of lignocellulose conversion processes potentially offers many advantages over lower‐solids loadings, including increased sugar and ethanol concentrations and decreased production and capital costs. Since the term lignocellulosic materials refers to a wide range of feedstocks (agricultural and forestry residues, distillery by‐products, and dedicated energy crops like grasses), the term “solids loading” here is defined by the amount of dry material that enters the process divided by the total mass of material and water added to the material. The goal of this study is to provide a consolidated review of studies using a high‐solids pretreatment step in the conversion process. Included in this review is a brief discussion of the limitations, such as the lack of available water to promote mass transfer, increased substrate viscosity, and increased concentration of inhibitors produced affecting pretreatment, as well as descriptions and findings of pretreatment studies performed at high solids, the latest reactor designs developed for pretreatment at bench‐ and pilot‐scales to address some of the limitations, and high‐solids pretreatment operations that have been scaled‐up and incorporated into demonstration facilities.

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Published in Biotechnology & Bioengineering, v. 109, issue 6, p. 1430-1442.

Copyright © 2012 Wiley Periodicals, Inc.

This is the peer reviewed version of the following article: Modenbach, A. A., & Nokes, S. E. (2012). The use of high-solids loadings in biomass pretreatment - a review. Biotechnology & Bioengineering, 109(6), 1430-1442. doi: 10.1002/bit.24464, which has been published in final form at https://doi.org/10.1002/bit.24464. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

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The authors gratefully acknowledge the financial support of the United States Department of Agriculture National Institute for Food and Agriculture Biomass Research and Development Initiative Grant #1100000836 and Grant # 2011-10006-30363.

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The investigation reported in this paper (No. 11-05-086) is a part of a project of the Kentucky Agricultural Experiment Station and is published with the approval of the director.