Matching Items (19)
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- All Subjects: Biofuels
- Creators: Chemical Engineering Program
- Creators: Vermaas, Willem
Description
The microalgae Scenedesmus have been regarded as a potential source for biofuel production, having up to ~30% of dry weight as lipids used for biodiesel fuel production. Electro-selective fermentation (ESF) is a novel approach that can selectively degrade proteins and carbohydrates while conserving lipids within algal cells, while simultaneously enhancing lipid wet-extraction and biohydrogenation. ESF is a combination of SF and Microbial Electrolysis Cell (MEC) technologies. Experiments reported here prove that ESF is an effective means of enhancing lipid wet-extraction by ~50% and achieving 36% higher lipid saturation conversion, compared to SF, over 30 days of semi-continuous operation. Anode-respiring bacteria (ARB) residing on the anode surface produced a current that led to increased rate of organic substrate utilization, protein degradation, and ultimately enhanced lipid extraction and biohydrogenation that converted unsaturated to saturated fatty-acids. Thus, ESF provides a promising method for enhancing lipid extraction for biofuel production.
ContributorsRastogi, Neil K (Author) / Rittmann, Bruce (Thesis director) / Liu, Liu (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
To efficiently produce biofuels and meet the planet’s rising energy demands, different biofuel production methods need to be developed and improved. One of the ways is to produce fatty acid methyl esters (FAMEs) in Synechocystis sp. PCC 6803, a versatile strain of cyanobacteria. In this thesis, Synechocystis was engineered to produce and excrete methyl laurate. In this pathway, first, lauroyl-ACP from fatty acid biosynthesis is converted to laurate by a thioesterase (TE) from Umbellularia californica. Then, the laurate is methylated to methyl laurate by a juvenile hormone acid O-methyltransferase (DmJHAMT) from Drosophila melanogaster. The TE/∆slr1609 strain of Synechocystis sp. PCC 6803 contains the TE gene and lacks the slr1609 gene encoding an acyl–acyl carrier protein synthetase, which functions in free fatty acid reuptake. The DmJHAMT gene was introduced into this strain for FAME production.
The DmJHAMT gene was cloned into a vector that contains neutral sites from the Synechocystis genome, making it suitable for homologous recombination, and a kanamycin resistance gene, for selection. The obtained plasmid was verified using restriction digests and Sanger sequencing. The sequence analysis and comparison of the cDNA in the obtained plasmid and the mRNA transcript of the same gene revealed three amino acid differences. Subsequent comparison with homologous genes in other Drosophila species revealed the differences in the cDNA match those of the other species, and thus, the gene most likely is functional.
The plasmid was transformed into Synechocystis, and PCRs were used to confirm proper integration and segregation. The TE/∆slr1609/DmJHAMT strain produced 62 mg/L methyl laurate in 12 days under a light intensity of 150 µmol photons m-2 s-1, bubbled with 0.5% CO2 at a rate of 30 mL/min, and supplemented with 0.5 mM methionine. The laurate levels did not decrease over time, but instead, remained stagnant after day 3. When the strain was grown in the same conditions without methionine, the laurate concentrations continued to increase above 400 µM, suggesting minimal methyl laurate production and thus a strong need for methionine supplementation. This work provides further evidence of the viability and success of the introduced FAME production pathway, and improved efficiency may be gained in the future.
The DmJHAMT gene was cloned into a vector that contains neutral sites from the Synechocystis genome, making it suitable for homologous recombination, and a kanamycin resistance gene, for selection. The obtained plasmid was verified using restriction digests and Sanger sequencing. The sequence analysis and comparison of the cDNA in the obtained plasmid and the mRNA transcript of the same gene revealed three amino acid differences. Subsequent comparison with homologous genes in other Drosophila species revealed the differences in the cDNA match those of the other species, and thus, the gene most likely is functional.
The plasmid was transformed into Synechocystis, and PCRs were used to confirm proper integration and segregation. The TE/∆slr1609/DmJHAMT strain produced 62 mg/L methyl laurate in 12 days under a light intensity of 150 µmol photons m-2 s-1, bubbled with 0.5% CO2 at a rate of 30 mL/min, and supplemented with 0.5 mM methionine. The laurate levels did not decrease over time, but instead, remained stagnant after day 3. When the strain was grown in the same conditions without methionine, the laurate concentrations continued to increase above 400 µM, suggesting minimal methyl laurate production and thus a strong need for methionine supplementation. This work provides further evidence of the viability and success of the introduced FAME production pathway, and improved efficiency may be gained in the future.
ContributorsSharma, Shuchi (Author) / Vermaas, Willem (Thesis director) / Wang, Xuan (Committee member) / Li, Shuqin (Committee member) / Computer Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
While biodiesel production from photosynthesizing algae is a promising form of alternative energy, the process is water and nutrient intensive. I designed a mathematical model for a photobioreactor system that filters the reactor effluent and returns the permeate to the system so that unutilized nutrients are not wasted, addressing these problems. The model tracks soluble and biomass components that govern the rates of the processes within the photobioreactor (PBR). It considers light attenuation and inhibition, nutrient limitation, preference for ammonia consumption over nitrate, production of soluble microbial products (SMP) and extracellular polymeric substance (EPS), and competition with heterotrophic bacteria that predominately consume SMP. I model a continuous photobioreactor + microfiltration system under nine unique operation conditions - three dilution rates and three recycling rates. I also evaluate the health of a PBR under different dilution rates for two values of qpred. I evaluate the success of each run by calculating values such as biomass productivity and specific biomass yield. The model shows that for low dilution rates (D = <0.2 d-1) and high recycling rates (>66%), nutrient limitation can lead to a PBR crash. In balancing biomass productivity with water conservation, the most favorable runs were those in which the dilution rate and the recycling rate were highest. In a second part of my thesis, I developed a model that describes the interactions of phototrophs and their predators. The model also shows that dilution rates corresponding to realistic PBR operation can washout predators from the system, but the simulation outputs depend heavily on the accuracy of parameters that are not well defined.
ContributorsWik, Benjamin Philip (Author) / Marcus, Andrew (Thesis director) / Rittmann, Bruce (Committee member) / School of Sustainability (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Hydrothermal Liquefaction of Algae represents one of many pathways for the sustainable replacement of fossil fuels in transportation. When processing and researching algal biofuel, determination of the higher heating value (HHV) is paramount. Bomb calorimetry represents to current method for direct determination of HHV. When determining HHV’s indirectly, the industry standard is using one of many linear correlations relating elemental composition to HHV. Most of these correlations were developed from coal industry data, meaning that they do not necessarily fit algal product data well. In this study bomb calorimetry data and CHNS/O elemental composition data were collected for Chlorella, Micract, GS 5587.1, Kirchnella, and Gal 87.1 MM8 algae species. This data was added to CHNS/O and HHV values for other algal products in literature, and utilized to test the accuracy of the Dulong, Gumz, Vandralek and Boie correlations for algae products. Several preliminary algae specific correlations were proposed through a linear regression model of the data. Of the 5 samples tested, Kirchnella exhibited the highest HHV (23.2405 ± 0.0216 MJ/kg) and Chlorella exhibited the lowest (20.2055 ± 0.0484 MJ/kg). For both the experimental, and literature CHNS/O vs HHV data, the Vandralek and Boie correlations provided the best approximations in this study. For the totality of the data collected and researched in this study, 6 of 8 proposed correlations outperformed the Vandralek equation for HHV approximation. The most promising proposed correlations incorporated multiple linear regressions for elemental fractions of CHS, CHSO and CHNSO. Being that only 20 distinct algal product samples were regressed to create the proposed correlations, more data should be incorporated before publication of a final correlation. This study should serve as a starting point for the compilation of an exhaustive database for algal product assay and HHV data.
ContributorsCopp, Connor Joseph (Author) / Deng, Shuguang (Thesis director) / Muppaneni, Tapaswy (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
A growing number of stylists \u2014 cosmetologists \u2014 are finding it harder to afford the basic necessities such as rent. However, the ever-increasing presence of smartphones and the increasing need for on-demand services like Uber and Uber Eats creates a unique opportunity for stylists \u2014 Clippr. Clippr is an application that aims to connect individual stylists directly to their customers. The application gives stylists a platform to create and display their own prices, services, and portfolio. Customers get the benefit of finding a stylist that suits them and booking instantly. This project outlines the backend for the Clippr application. It goes over the framework, REST API, and various functionalities of the application. Additionally, the project also covers the work that is still needed to successfully launch the application.
ContributorsKamath, Sanketh (Author) / Olsen, Christopher (Thesis director) / Sebold, Brent (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Acyl Carrier Protein (ACP) is a small, acidic protein that plays an essential role in fatty acid synthesis by elongating fatty acid chains. ACP was isolated from an extract of a modified strain of Synechocystis sp. PCC 6803 that contains a thioesterase and from which the acyl-ACP synthetase has been deleted. Using ammonium sulfate precipitation to isolate a crude protein fraction containing ACP, immunoblot analysis was performed to determine relative amounts of free and acylated-ACP in the cell. The nature of fatty acids attached to ACP was determined by creating butylamide derivatives that were analyzed using GC/MS. Immunoblot analysis showed a roughly 1:1 ratio of acylated ACP to free ACP in the cell depending on the nutritional state of the cell. From GC/MS data it was determined that palmitic acid was the predominate component of acyl groups attached to ACP. The results indicate that there is a significant amount of acyl-ACP, a feedback inhibitor of early steps in the fatty acid biosynthesis pathway, in the cell. Moreover, the availability of free ACP may also limit fatty acid biosynthesis. Most likely it is necessary for ACP to be overexpressed or to have the palmitic acid cleaved off in order to synthesize optimal amounts of lauric acid to be used for cyanobacterial biofuel production.
ContributorsWu, Sharon Gao (Author) / Vermaas, Willem (Thesis director) / Redding, Kevin (Committee member) / School of Sustainability (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Molecular Sciences (Contributor) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Even though access to purified water has improved, there are still many people and locations that do not have this convenience. Approximately 1.2 billion people lack access to safe drinking water and 2.6 billion people have little or no sanitation. Furthermore, breakthroughs in water purification technology are essential to combat these issues. While there are several approaches to water purification, membrane processes are widely used based on their numerous advantages, including high operating temperature and low energy input. In essence, membranes do not require chemical additives, thermal inputs, or regeneration of spent media. The spin coating procedure was used to make a total of 94 membrane samples by adjusting the following variables: membrane support, membrane wetting, solvent, polyacrylonitrile (PAN) content, water contant, Linde Type A (LTA) zeolite content, and the rotations per minute (RPM) of the spin coater. Parameters that were held constant include PAN for the permeable dispersion layer, LTA zeolites as the inorganic filler material, and a spin time of 30 seconds for the spin coater. There were key findings in both the preliminary and core data sets. From the preliminary membrane samples 1 \u2014 40, a baseline was established to use for the core data: polysulfone (PSf) support, 1 \u2014 3% PAN content, and 1 \u2014 3% LTA zeolite content. Flux analysis revealed many inconsistencies in groups 1 \u2014 13 such as unreasonably high error bars (+50%), flow rates that were near zero or extremely high (+15,000 L hr-1 m-2), and lack of a clear trend for membrane specifications. Membranes with a high degree of polymer \u2014 zeolite aggregation on the surface had very low flux values. A higher flux of 4,700 L hr-1 m-2 was correlated to gap and hole formation on the membrane surface. It was shown in group 7 that an increasing degree of surface defects corresponded to an increasing flux of 17,000 L hr-1 m-2. Although the target flux for a defect \u2014 free membrane lies between 500 \u2014 4,000 L hr-1 m-2, there were not any groups with flux values in this range. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) analysis revealed that the observed group similarities could not be attributed to individual membrane specifications. However, this data showed chemical fingerprint overlap across all groups, which were synthesized with varying quantities of the same chemicals. Analysis of flux data, SEM images, and ATR-FTIR data all suggest that the spin coating procedure leads to inconsistent results. Although the spin coater provides flexibility in user control, its advantages are outweighed by the limited control of surface uniformity, zeolite dispersion, and defect formation. It has been shown that the spin coating process is not compatible with the formation of a uniform polymer \u2014 zeolite layer in these experiments.
ContributorsMaltagliati, Alexander Justin (Author) / Lind, Mary Laura (Thesis director) / Durgun, Pinar Cay (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Carbon capture is an essential way to reduce greenhouse gas emissions. One way to decrease the emissions is through the use of adsorbents such as zeolites. Dr. Dong-Kyun Seo’s group (School of Molecular Sciences, Arizona State University) synthesized the nanostructured faujasite (NaX). The zeolite was characterized using Scanning Electron Microscopy (SEM) and the physisorption properties were determined using ASAP 2020. ASAP 2020 tests of the nano-zeolite pellets at 77K in a liquid N2 bath determined the BET surface area of 547.1 m2/mol, T-plot micropore volume of 0.2257 cm3/g, and an adsorption average pore width of 5.9 Å. The adsorption isotherm (equilibrium) of CH4, N2, and CO2 were measured at 25ºC. Adsorption isotherm experiments concluded that the linear isotherm was the best fit for N2, and CH4 and the Sips isotherm was a better fit than the Langmuir and Freundlich isotherm for CO2. At 25ºC and 1 atm the zeolite capacity for CO2 is 4.3339 mmol/g, 0.1948 mmol/g for CH4, and 0.3534 mmol/g for N2. The zeolite has a higher CO2 capacity than the conventional NaX zeolite. Breakthrough experiments were performed in a fixed bed 22in, 0.5 in packing height and width at 1 atm and 298 K with nano-zeolite pellets. The gas chromatographer tested and recorded the data every two minutes with a flow rate of 10 cm3/min for N2 and 10 cm3/min CO2. Breakthrough simulations of the zeolite in a fixed bed adsorber column were conducted on MATLAB utilizing varying pressures, flow rates, and fed ratios of various CO2, N2 and CH4. Simulations using ideal adsorbed solution theory (IAST) calculations determined that the selectivity of CO2 in flue gas (15% CO2 + 85% N2) is 571.79 at 1 MPa, significantly higher than commercial zeolites and literature. The nanostructured faujasite zeolite appears to be a very promising adsorbent for CO2/N2 capture from flue gas and the separation of CO2/N2.
ContributorsClark, Krysta D. (Author) / Deng, Shuguang (Thesis director) / Green, Matthew (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Carbon capture has been a highly sought-after technology for decades because of its<br/>capabilities to restore atmospheric damage done by greenhouse gasses. Thanks to evolving<br/>separation techniques, carbon capture is becoming more efficient with every new discovery in<br/>the field. Currently the biggest problems that carbon capture are facing is the cost of<br/>manufacturing material to aid the process and obtaining ideal conditions for removal of carbon<br/>from air and devising solutions for removal of CO2 in ambient and flue gas conditions.<br/>This Honors Thesis is a continuation of Dr. Shuguang Deng and Dr. Mai Xu’s research<br/>initiative to manufacture and test various zeolitic CO2 removal efficiencies. The goals of this<br/>Honors Thesis are to investigate the adsorption/desorption kinetics and isothermal equilibrium<br/>CO2 capacity of a NaX nanozeolite under ambient air conditions.<br/>What was determined from the following testing was that the zeolite of interest had a<br/>higher adsorption capacity of CO2 at lower temperatures, had a maximum equilibrium quantity<br/>adsorbed of 0.203 mmol/g for CO2 and 0.367 mmol/g of N2, had a maximum breakthrough CO2<br/>capacity of 0.101 mmol of CO2 per gram of zeolite at dry conditions and 298.15K and this<br/>linearly decreased to 0.040 mmol/g at 25% relative humidity.
ContributorsBonelli, Xavier Berlage (Author) / Deng, Shuguang (Thesis director) / Xu, Mai (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05