The potential of oleaginous yeast Rhodotorula glutinis for the sustainable production of biodiesel feedstock via fermentation of lignocellulosic biomass in pulp and paper wastewater as a fermentation media was investigated. The overall objective was to increase the levels of lipid feedstock in oleaginous yeast in order to reduce biodiesel production cost. To meet sustainable production of biodiesel, industrial wastewater and waste lignocellulose biomass were used as cultivation media and carbon source, respectively. Pulp and paper wastewater effluent was selected as a source of water and nutrients for the production of microbial lipids due to its environmental pollution as it creates large volume of wastewater discharge with high chemical oxygen demand (COD). Since medium composition and process fermentation condition can significantly affect the fermentative performance of oleaginous microorganisms, to find the optimum cultivation condition, design of experiment combined with RSM optimization technique was performed, which has been shown to be successful to predict the optimum condition for the biomass and lipid production in batch fermentation. In addition, lignocellulosic biomass hydrolysate was used as a substrate to improve the cost associated with feedstock fermentation. Lignocellulosic hydrolysate, a product of degradation of lignocelllosic biomass, contains degradation by-products such as 5- hydroxymethylfurfural (HMF), furfural and acetic acid that are known as major inhibitors that influences microorganism growth process. Therefore, their impacts on the fermentative performance and lipid productivity of oleaginous yeast were explored. A detailed operating condition and equipment design for the process of biocrude production from pulp and paper wastewater on a commercial scale was developed. A technological assessment of the process was performed to evaluate their technical benefits and limitations. Results show that pulp and paper wastewater can be used as a cultivation media for the production of microbial lipids using R. glutinis. However, its carbon content has to be improved. Analysis of the design and cost of the process showed that acid hydrolysis process using paper mill sludge as lignocellulosic biomass required the smallest process equipment units but at a higher raw material cost compared to fermentation process.

<p>Controllable continuous feeding of biomass feedstock in a biorefinery is critical to upscaling current ethanol conversion techniques to a commercial scale. Mechanical pretreatment of biomass feedstock performed using a compression feed screw (CFS) improves the ethanol yield but is subject to flowability issues, especially the plugging of biomass. The mechanical behavior, and hence, the flowability of biomass feedstock, is strongly affected by several factors, including preparation method, moisture content, physical composition, and particle size distribution. In addition, the current design of CFS is guided by limited experimentation and even fewer theoretical correlations. This thesis aims at developing computational methods to model the flow of densified feedstock in a CFS and experimental techniques to characterize the mechanical properties required for the model. We adopted a modified Drucker-Prager Cap constitutive (mDPC) law for milled corn stover (a widely used feedstock for bioethanol production) to model the material’s rate-independent bulk behavior in a CFS. The mDPC elastoplastic law captures the frictional shear and permanent volumetric changes in corn stover using a continuous porosity-dependent yield surface. The parameters of the mDPC model are calibrated using a unified set of single-ended die compaction and multiple shear failure tests. In addition, we quantified the changes in the mDPC parameters with moisture content up to the water-holding capacity of corn stover particles. A Coupled Eulerian-Lagrangian Finite Element Method model developed for the CFS geometry predicts the deformation of the material using the calibrated mDPC parameters. We model the interaction between the material and the CFS surface using a Coulomb wall friction coefficient calibrated using the Janssen-Walker method for a punch and die system. A laboratory-scale compression feed screw is designed and fabricated to characterize the flow of dense granular materials in collaboration with undergraduate students in the School of Mechanical Engineering. FEM model predictions of feeding torque and mass flow rate are validated against the laboratory-scale feeder for microcrystalline cellulose Avicel PH-200 and milled corn stover. The model predictions agree with the experiments for Avicel PH-200 but have a higher error in the case of corn stover. Some physical effects, such as shear hardening and particle erosion observed in milled corn stover, are not captured using the current implementation of the mDPC model, which explains the different model accuracies for both materials. The continuum model is used to uncover material density distribution, torque, and pressure inside the CFS, otherwise challenging through experiments. The FEM model showed a significantly higher sensitivity of the feeder performance to two material properties, namely the hydrostatic yield stress and the wall friction coefficient. The characterized variation of material properties with moisture content and the effect of each material property on the feeder performance provide strategies to engineer the feedstock for better flowability. Further, the continuum model offers a method to study design changes before manufacturing the equipment. Finally, we propose the possibility of a reduced-order analytical model based on the critical material properties and the material deformation mechanism demonstrated by the FEM model.</p>