Chemical Engineering Commons^™

Microalgae Immobilization With Filamentous Fungi: Process Development For Sustainable Food Systems, Suvro Talukdar

Theses and Dissertations--Biosystems and Agricultural Engineering

Demand for sustainable food sources has increased because of the rapid growth of the world's population.  In this study, microalgae cells of Haematococcus pluvialis were immobilized using the edible fungal strain Aspergillus awamori for potential food applications. The study investigated the impact of fungal loading, pellet geometry, and initial microalgae cell concentration on the immobilization performance and product characteristics. It was found that higher fungal loading and larger fungal pellets contributed to increased immobilization performance while increased initial microalgae concentration inhibited the process. Larger fungal pellets had decreased biomass density, which led to decreased surface concentration of immobilized microalgae but …

A Process Intensification Approach To Improve Volatile Fatty Acids Production, Extraction, And Valorization, Can Liu

Theses and Dissertations--Biosystems and Agricultural Engineering

Anaerobic digestion (AD) is a widely used biowaste conversion method. Recent studies have explored arrested methanogenesis as an alternative approach to leverage existing AD facilities and produce volatile fatty acids (VFAs) instead of biogas. VFAs have been recognized as precursors for a range of value-added chemicals and bioproducts. Arrested methanogenesis involves inducing acidic fermentation by halting the AD process before methanogenesis. It has been found that higher organic loading and thermophilic conditions enhance VFA accumulation and stabilize the acidic fermentation (AF) system.

Brewer's spent grain (BSG), a significant by-product of the brewing industry, was employed as the feedstock for VFA …

Lignin Valorization Via Reductive Depolymerization Using Promoted Nickel Catalysts And Sub- And Supercritical Methanol, Julia Parker

Theses and Dissertations--Biosystems and Agricultural Engineering

While lignin has been regarded as the most promising renewable feedstock for the sustainable manufacture of aromatic compounds, lignin valorization is necessary to improve the economic viability of biorefineries. Reductive catalytic fractionation (RCF), which combines delignification and lignin depolymerization into a single stage while maintaining the structure and integrity of the cellulose component, has evolved as an effective method for processing biomass. The ability of Cu and Fe to promote the performance of a 20% Ni/alumina catalyst when converting native lignin to alkylphenols by RCF in sub- and supercritical methanol was tested. The effectiveness of lignin extraction as measured by …

Extraction Of Micro- And Nano-Plastic Particles From Water Using Hydrophobic Natural Deep Eutectic Solvents, Jameson R. Hunter

Theses and Dissertations--Biosystems and Agricultural Engineering

The production of plastic and the amount of waste plastic that enters the environment increases every year. Synthetic polymers will gradually break down into particles on the micro- and nano-scale. The micro- and nano-plastics pose a significant ecological harm by transporting toxic chemicals and causing inflammation and cellular damage when ingested. Two common plastics are polyethylene terephthalate (PET) and Polystyrene (PS), and a newer bioplastic polylactic acid (PLA) that has become a popular alternative. Deep eutectic solvents are a recently discovered solvent composed of a hydrogen bond donor and hydrogen bond acceptor and have been proposed as a cheaper alternative …

Linking Lignin Source With Structural And Electrochemical Properties Of Lignin-Derived Carbon Materials, Wenqi Li, Yan Zhang, Lalitendu Das, Yikai Wang, Mi Li, Namal Wanninayake, Yunqiao Pu, Doo Young Kim, Yang-Tse Cheng, Arthur J. Ragauskas, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Valorization of lignin to high-value chemicals and products along with biofuel production is generally acknowledged as a technology platform that could significantly improve the economic viability of biorefinery operations. With a growing demand for electrical energy storage materials, lignin-derived activated carbon (AC) materials have received increasing attention in recent years. However, there is an apparent gap in our understanding of the impact of the lignin precursors (i.e., lignin structure, composition and inter-unit linkages) on the structural and electrochemical properties of the derived ACs. In the present study, lignin-derived ACs were prepared under identical conditions from two different lignin …

Catalytic Oxidation And Depolymerization Of Lignin In Aqueous Ionic Liquid, Lalitendu Das, Siquan Xu, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Lignin is an integral part of the plant cell wall, which provides rigidity to plants, also contributes to the recalcitrance of the lignocellulosic biomass to biochemical and biological deconstruction. Lignin is a promising renewable feedstock for aromatic chemicals; however, an efficient and economic lignin depolymerization method needs to be developed to enable the conversion. In this study, we investigated the depolymerization of alkaline lignin in aqueous 1-ethyl-3-methylimidazolium acetate [C₂C₁Im][OAc] under oxidizing conditions. Seven different transition metal catalysts were screened in presence of H₂O₂ as oxidizing agent in a batch reactor. CoCl₂ and …

Fractionation And Characterization Of Lignin Streams From Genetically Engineered Switchgrass, Enshi Liu

Theses and Dissertations--Biosystems and Agricultural Engineering

Development of biomass feedstocks with desirable traits for cost-effective conversion is one of the main focus areas in biofuels research. As suggested by techno-economic analyses, the success of a lignocellulose-based biorefinery largely relies on the utilization of lignin to generate value-added products, i.e. fuels and chemicals. The fate of lignin and its structural/compositional changes during pretreatment have received increasing attention; however, the effect of genetic modification on the fractionation, depolymerization and catalytic upgrading of lignin from genetically engineered plants is not well understood. This study aims to fractionate and characterize the lignin streams from a wild-type and two genetically engineered …

Capture And Recycle Of Industrial Co2 Emissions Using Mircoalgae, Michael H. Wilson, Daniel T. Mohler, John G. Groppo, Thomas E. Grubbs, Stephanie Kesner, E. Molly Frazar, Aubrey Shea, Czarena L. Crofcheck, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

A novel cyclic flow photobioreactor (PBR) for the capture and recycle of CO₂ using microalgae was designed and deployed at a coal-fired power plant (Duke Energy’s East Bend Station). The PBR was operated continuously during the period May–September 2015, during which algae productivity of typically 0.1–0.2 g/(L day) was obtained. Maximum CO₂ capture efficiency was achieved during peak sunlight hours, the largest recorded CO₂ emission reduction corresponding to a value of 81 % (using a sparge time of 5 s/min). On average, CO₂ capture efficiency during daylight hours was 44 %. The PBR at East Bend …

Lipid Extraction From Scenedesmus Sp. Microalgae For Biodiesel Production Using Hot Compressed Hexane, Hee-Yong Shin, Jae-Hun Ryu, Seong-Youl Bae, Czarena L. Crofcheck, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Lipid extraction from Scenedesmus sp. microalgae using hot compressed hexane (HCH) was investigated. Extraction performance was evaluated near the critical point of hexane and was compared with that of hexane extraction performed at room temperature and pressure, and the Bligh and Dyer extraction method. Experimental data showed that HCH significantly improves the lipid yield and rate of lipid extraction compared to the use of hexane at ambient conditions. High yields of biodiesel-convertible lipid fractions were rapidly achieved at the critical point of hexane, at a level comparable to that of the Bligh and Dyer method.

Co2 Recycling Using Microalgae For The Production Of Fuels, Michael H. Wilson, John Groppo, Andrew Placido, S. Graham, S. A. Morton Iii, Eduardo Santillan-Jimenez, Aubrey Shea, Mark Crocker, Czarena Crofcheck, Rodney Andrews

Center for Applied Energy Research Faculty and Staff Publications

CO₂ capture and recycle using microalgae was demonstrated at a coal-fired power plant (Duke Energy’s East Bend Station, Kentucky). Using an in-house designed closed loop, vertical tube photobioreactor, Scenedesmus acutus was cultured using flue gas as the CO₂ source. Algae productivity of 39 g/(m² day) in June–July was achieved at significant scale (18,000 L), while average daily productivity slightly in excess of 10 g/(m² day) was demonstrated in the month of December. A protocol for low-cost algae harvesting and dewatering was developed, and the conversion of algal lipids—extracted from the harvested biomass—to diesel-range hydrocarbons via catalytic …

Effects Of Sodium Hydroxide Pretreatment On Structural Components Of Biomass, Alicia A. Modenbach, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

Pretreatment is a unit operation in the conversion of biomass to valuable products that utilizes various combinations of conditions, including chemicals, heat, pressure, and time, to reduce the recalcitrance of lignocellulose. Many such pretreatments have been developed over the years, as the operating conditions can be adapted so that lignocellulose is modified in ways unique to each pretreatment. By tailoring pretreatment conditions to achieve these modifications, the types of final products produced can be controlled. The purpose of this review is to provide a consolidated source of information for sodium hydroxide effects on lignocellulose. The structural characteristics of lignocellulose and …

Mathematical Modeling Of Clostridium Thermocellum’S Metabolic Responses To Environmental Perturbation, Bless Adotey

Theses and Dissertations--Biosystems and Agricultural Engineering

Clostridium thermocellum is a thermophilic anaerobe that is capable of producing ethanol directly from lignocellulosic compounds, however this organism suffers from low ethanol tolerance and low ethanol yields. In vivo mathematical modeling studies based on steady state traditional metabolic flux analysis, metabolic control analysis, transient and steady states’ flux spectrum analysis (FSA) were conducted on C. thermocellum’s central metabolism. The models were developed in Matrix Laboratory software ( MATLAB^® (The Language of Technical Computing), R2008b, Version 7.7.0.471)) based on known stoichiometry from C. thermocellum pathway and known physical constraints. Growth on cellobiose from Metabolic flux analysis (MFA) and Metabolic …

Effects Of Growth Media Ph And Reaction Water Activity On The Conversion Of Acetophenone To (S)-1-Phenylethanol By Saccharomyces Cerevisiae Immobilized On Celite 635 And In Calcium Alginate, Nicholas P. Coleman, Czarena Crofcheck, Sue E. Nokes, Barbara L. Knutson

Biosystems and Agricultural Engineering Faculty Publications

Biologically catalyzed reactions often produce enantiomers of the product; however, only one configuration is desired. Reaction conditions are known to affect enantiomer ratios and reaction kinetics, but little is known regarding the effect of processing conditions on whole-cell biocatalysis. Saccharomyces cerevisiae cells were grown in batch on glucose at pH = 4, 5, and 7, and then immobilized on Celite beads or in calcium alginate beads and used as the biocatalyst for the conversion of acetophenone in hexane to (S)-1-phenylethanol at water activities of 0.37, 0.61, and 0.80. S. cerevisiae was used as a model microorganism for the whole-cell catalyzed …