Date of Award

2011

Degree Type

Thesis

Degree Name

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Lars Rehmann

Abstract

This thesis studied the toxic effects of model inhibitory compounds present in lignocellulosic biomass hydrolysate on the maximum specific growth rate (pmax), biomass yield co-efficient (Yx/s) and total growth time (Tt) on S.cerevisiae DSM 1334. These toxic compounds are formed or released during pre-treatment of lignocellulosic biomass, which is a renewable source of energy for biofuel production. The main and interaction effects of furfural, furfuryl alcohol, ferulic acid and p-coumaric acid were quantified using a fractional factorial design in combination with a high-throughput assay based on automated online optical density measurements. Furfural had the largest effect on all the three response variables, although the other compounds also had significant impact. Linear statistical models were developed and validated for pmax and Tf, which were used to create a suitable framework for developing a polymer-based removal system to mitigate the inhibitory effects of these compounds. Eight different polymers were screened for this purpose, and it was observed that styrene- polyvinylbenzene (XAD-4), low-density polyethylene (LDPE) and poly(l,4-phenylene- ether-ether-sulfone) (PEES) had the maximum affinity towards the compounds. A case study for the removal of furfural from aspen wood chip hydrolysate was investigated to study the effect of increasing polymer mass on pmax.

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