Noah D. Weiss has conducted his Ph.D. thesis in BioValue’s project 3. Below is a short summary of his findings and information on the defense.


PhD title: Understanding biomass-water interactions in high-solids lignocellulose bioconversion processes

To reduce the onset and impact of climate change, it is necessary to drastically reduce the consumption of fossil fuels. Biofuels and chemicals made from lignocellulosic biomass have been proposed as a promising alternative to fossil fuels and chemicals. However, production costs are currently higher for bio-based products in part due to biomass recalcitrance. More cost effective and sustainable processes must be developed. This thesis explores the relationship between water and lignocellulosic biomass, and seeks to understand how biomass-water interactions are related to and affect biomass recalcitrance. Furthermore, it explores how the high solids effect is related to biomass-water interactions, and how these interactions also impact solid-liquid separation processes during biomass conversion.

It was found that increased water retention and constraint by pretreated biomass correlated to increased cellulose conversion yields for a wide variety of pretreated materials from different pretreatment processes. This suggests that biomass-water interactions may be generally related to biomass recalcitrance. T1T2 NMR measurements showed significant changes to biomass-water interactions after pretreatment, with cell wall water becoming much less constrained. The high solids effect was found to be related to the disappearance of free water from the system, and to a collapsing of pores in the biomass with increased solids concentrations, as well as decreased diffusion rates. The high solids effect was reduced by modifying the pretreated biomass, suggesting that this effect can be reduced through tailored design of pretreatment methods. WRV and water constraint was found to increase during the course of enzymatic hydrolysis, most likely due to decreasing particle sizes. This suggests that solid liquid separations are more difficult after enzymatic hydrolysis. This work has provided important information about the role of water in causing the high solids effect, and to how modifications of the biomass could produce biomass which is less recalcitrant at high solids concentrations.

We hope that you will participate at Noah’s defense:

Time: Friday 25th of May at 13 o’clock

Place: KU-IGN (Institut for Geovidenskab og Naturforvaltning), Rolighedsvej 23, 1958 Frederiksberg C, Auditorium von Langen

Main supervisor: Senior researcher Lisbeth Garbrecht Thygesen

Contact information: Noah Daniel Weiss, e-mail: ndw@ign.ku.dk

Defense title: Understanding biomass-water interactions in high-solids lignocellulose bioconversion processes

Figure caption: LFNMR T2 profiles for (a) milled pretreated wheat straw (PWS), (b) de-lignified PWS, (c) xylanase treated PWS, and (d) Avicel, at different %DM, after NNLS analysis, with each peak representing a pool of water at a given constraint environment, and the area of the peak the relative amount of water in that pool within a given sample.