Matching Items (7)
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- All Subjects: Microalgae
- Creators: Rittmann, Bruce
- Creators: Sommerfeld, Milton
Description
Second-generation biofuel feedstocks are currently grown in land-based systems that use valuable resources like water, electricity and fertilizer. This study investigates the potential of near-shore marine (ocean) seawater filtration as a source of planktonic biomass for biofuel production. Mixed marine organisms in the size range of 20µm to 500µm were isolated from the University of California, Santa Barbara (UCSB) seawater filtration system during weekly backwash events between the months of April and August, 2011. The quantity of organic material produced was determined by sample combustion and calculation of ash-free dry weights. Qualitative investigation required density gradient separation with the heavy liquid sodium metatungstate followed by direct transesterification and gas chromatography with mass spectrometry (GC-MS) of the fatty acid methyl esters (FAME) produced. A maximum of 0.083g/L of dried organic material was produced in a single backwash event and a study average of 0.036g/L was calculated. This equates to an average weekly value of 7,674.75g of dried organic material produced from the filtration of approximately 24,417,792 liters of seawater. Temporal variations were limited. Organic quantities decreased over the course of the study. Bio-fouling effects from mussel overgrowth inexplicably increased production values when compared to un-fouled seawater supply lines. FAMEs (biodiesel) averaged 0.004% of the dried organic material with 0.36ml of biodiesel produced per week, on average. C16:0 and C22:6n3 fatty acids comprised the majority of the fatty acids in the samples. Saturated fatty acids made up 30.71% to 44.09% and unsaturated forms comprised 55.90% to 66.32% of the total chemical composition. Both quantities and qualities of organics and FAMEs were unrealistic for use as biodiesel but sample size limitations, system design, geographic and temporal factors may have impacted study results.
ContributorsPierre, Christophe (Author) / Olson, Larry (Thesis advisor) / Sommerfeld, Milton (Committee member) / Brown, Albert (Committee member) / Arizona State University (Publisher)
Created2011
Description
Population growth and fresh water depletion challenge drinking water utilities. Surface water quality is impacted significantly by climate variability, human activities, and extreme events like natural disasters. Dissolved organic carbon (DOC) is an important water quality index and the precursor of disinfection by-products (DBPs) that varies with both hydrologic and anthropogenic factors. Granular activated carbon (GAC) is a best available technology for utilities to meet Stage 2 D/DBP rule compliance and to remove contaminants of emerging concern (CECs) (e.g., pharmaceutical, personal care products (PCPs), etc.). Utilities can operate GAC with more efficient and flexible strategies with the understanding of organic occurrence in source water and a model capable predicting DOC occurrence. In this dissertation, it was found that DOC loading significantly correlated with spring runoff and was intensified by dry-duration antecedent to first flush. Dynamic modeling based on reservoir management (e.g., pump-back operation) was established to simulate the DOC transport in the reservoir system. Additionally, summer water recreational activities were found to raise the level of PCPs, especially skin-applied products, in raw waters. GAC was examined in this dissertation for both carbonaceous and emerging nitrogenous DBP (N-DBP) precursors (i.e., dissolved organic nitrogen (DON)) removal. Based on the experimental findings, GAC preferentially removes UV254-absorbing material, and DOC is preferentially removed over DON which may be composed primarily of hydrophilic organic and results in the low affinity for adsorption by GAC. The presence of organic nitrogen can elevate the toxicity of DBPs by forming N-DBPs, and this could be a major drawback for facilities considering installation of a GAC adsorber owing to the poor removal efficiency of DON by GAC. A modeling approach was established for predicting DOC and DON breakthrough during GAC operation. However, installation of GAC adsorber is a burden for utilities with respect to operational and maintenance cost. It is common for utilities to regenerate saturated GAC in order to save the cost of purchasing fresh GAC. The traditional thermal regeneration technology for saturated GAC is an energy intensive process requiring high temperature of incineration. Additionally, small water treatment sites usually ship saturated GAC to specialized facilities for regeneration increasing the already significant carbon footprint of thermal regeneration. An innovative GAC regeneration technique was investigated in this dissertation for the feasibility as on-site water treatment process. Virgin GAC was first saturated by organic contaminant then regenerated in-situ by iron oxide nanocatalysts mixed with hydrogen peroxide. At least 70 % of adsorption capacity of GAC can be regenerated repeatedly for experiments using modeling compound (phenol) or natural organic matter (Suwannee River humic acid). The regeneration efficiency increases with increasing adsorbate concentration. Used-iron nanocatalysts can be recovered repeatedly without significant loss of catalytic ability. This in-situ regeneration technique provides cost and energy efficient solution for water utilities considering GAC installation. Overall, patterns were found for DOC and CEC variations in drinking water sources. Increasing concentrations of bulk (DOC and DON) and/or trace organics challenge GAC operation in utilities that have limited numbers of bed-volume treated before regeneration is required. In-situ regeneration using iron nanocatalysts and hydrogen peroxide provides utilities an alternative energy-efficient operation mode when considering installation of GAC adsorber.
ContributorsChiu, Chao-An (Author) / Westerhoff, Paul (Thesis advisor) / Rittmann, Bruce (Committee member) / Hristovski, Kiril (Committee member) / Arizona State University (Publisher)
Created2012
Description
Cyanobacteria and microalgae help reduce the environmental impact of human energy consumption by playing a vital role in carbon and nitrogen cycling. They are also used in various applications like biofuel production, food, medicine, and bioremediation. Understanding how these organisms respond to stress is important for efficient recovery strategies and sustainable outcomes. This study investigated the effects of low-level bleaching and thermal stress on cyanobacteria and microalgae, specifically Synechocystis, Chlorella, and Scenedesmus. The role of ferroptosis, an iron-dependent form of cell death, in the degradation of cellular components under these stressors was examined. Flow cytometry and spectrophotometry were used to measure changes in cellular health and viability. The results showed that temperature influences the type of cell death mechanism and can impact photosynthetic organisms. When treated with Liproxstatin-1, an inhibitor of ferroptosis, both Synechocystis and Chlorella experienced a decrease in oxidative damage, suggesting a potential protective role for the compound. Further investigation into ferroptosis and other forms of cell death, as well as identifying additional inhibitory molecules, could lead to strategies for mitigating oxidative stress and enhancing the resilience of cyanobacteria and microalgae.
ContributorsRayes, Rammy (Author) / Rittmann, Bruce (Thesis director) / Eustance, Everett (Committee member) / Lewis, Christine (Committee member) / Khdour, Omar (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2023-05
Description
Recognition of algae as a “Fit for Purpose” biomass and its potential as an energy and bio-product resource remains relatively obscure. This is due to the absence of tailored and unified production information necessary to overcome several barriers for commercial viability and environmental sustainability. The purpose of this research was to provide experimentally verifiable estimates for direct energy and water demand for the algal cultivation stage which yields algal biomass for biofuels and other bio-products. Algal biomass productivity was evaluated using different cultivation methods in conjunction with assessment for potential reduction in energy and water consumption for production of fuel and feed. Direct water and energy demands are the major focal sustainability metrics in hot and arid climates and are influenced by environmental and operational variables connected with selected algal cultivation technologies. Evaporation is a key component of direct water demand for algal cultivation and directly related to variations in temperature and relative humidity. Temperature control strategies relative to design and operational variables were necessary to mitigate overheating of the outdoor algae culture in panel photobioreactors and sub-optimal cultivation temperature in open pond raceways. Mixing in cultivation systems was a major component in direct energy demand that was provided by aeration in panel bioreactors and paddlewheels in open pond raceways. Management of aeration time to meet required biological interactions provides opportunities for reduced direct energy demand in panel photobioreactors. However, the potential for reduction in direct energy demand in raceway ponds is limited to hydraulics and head loss. Algal cultivation systems were reviewed for potential integration into dairy facilities in order to determine direct energy demand and nutrient requirements for algal biomass production for animal feed. The direct energy assessment was also evaluated for key components of related energy and design parameters for conventional raceway ponds and a gravity fed system. The results of this research provide a platform for selecting appropriate production scenarios with respect to resource use and to ensure a cost effective product with the least environmental burden.
ContributorsBadvipour, Shahrzad (Author) / Sommerfeld, Milton (Thesis advisor) / Downes, Meghan (Committee member) / Abbott, Joshua (Committee member) / Chester, Mikhail (Committee member) / Arizona State University (Publisher)
Created2015
Description
Microalgae represent a potential sustainable alternative for the enhancement and protection of agricultural crops. The dry biomass and cellular extracts of Scenedesmus dimorphus were applied as a biofertilizer, a foliar spray, and a seed primer to evaluate seed germination, plant growth, and crop yield of Roma tomato plants. The dry biomass was applied as a biofertilizer at 50 g and 100 g per plant, to evaluate its effects on plant development and crop yield. Biofertilizer treatments enhanced plant growth and led to greater crop (fruit) production. Timing of biofertilizer application proved to be of importance - earlier 50 g biofertilizer application resulted in greater plant growth. Scenedesmus dimorphus culture, growth medium, and different concentrations (1%, 5%, 10%, 25%, 50%, 75%, 100%) of aqueous cell extracts were used as seed primers to determine effects on germination. Seeds treated with Scenedesmus dimorphus culture and with extract concentrations higher than 50 % (0.75 g ml-1) triggered faster germination - 2 days earlier than the control group. Extract foliar sprays of 50 ml and 100 ml, were obtained and applied to tomato plants at various extract concentrations (10%, 25%, 50%, 75% and 100%). Plant height, flower development and number of branches were significantly enhanced with 50 % (7.5 g ml-1) extracts. Higher concentration sprays led to a decrease in growth. The extracts were further screened to assess potential antimicrobial activity against the bacterium Escherichia coli ATCC 25922, the fungi Candida albicans ATCC 90028 and Aspergillus brasiliensis ATCC 16404. No antimicrobial activity was observed from the microalga extracts on the selected microorganisms.
ContributorsGarcia-Gonzalez, Jesus (Author) / Sommerfeld, Milton (Thesis advisor) / Steele, Kelly (Committee member) / Henderson, Mark (Committee member) / Arizona State University (Publisher)
Created2014
Description
In order for microalgae to be a cost-effective renewable energy source, a high CO2-transfer efficiency (CTE) is necessary. Using hollow-fiber membranes (HFM), membrane carbonation (MC) in microalgal cultivation can be used to achieve a CTE near 100%. Due to the diurnal cycle in outdoor algal cultivation, an inconsistent CO2 demand with temperature fluctuations can cause pore wetting of the inner and outer fiber layers in composite HFMs. In addition, the presence of supersaturated O2 during high algal growth may change the gas transfer dynamics of the fibers, which can be critical when trying to selectively remove CO2 from a valuable gas such as biogas. This study evaluated fiber performance under conditions that mimic these effects by analyzing the carbon transfer efficiency (CTE), CO2 flux (JCO2), and outlet CO2 concentration compared to baseline values. Wetting of the interior fiber macropores resulted in an average 32% ± 8.3% decrease in flux, which was greater than for flooding of the outer macropores, which showed no significant change. All tests resulted in a decrease in CTE and an increase in outlet CO2. The presence of elevated O2 levels did not decrease the CO2 flux compared to baseline values, but it increased the O2 concentration and decreased the CH4 concentration at the distal end of the fibers. These findings highlight that liquid accumulation can decrease HFM performance during MC for microalgal cultivation, while the presence of supersaturated O2 can reduce separation efficiency.
ContributorsFrias, Zoe (Author) / Rittmann, Bruce (Thesis director) / Eustance, Everett (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor) / School of Life Sciences (Contributor)
Created2021-12
Description
The need for clean fuel sources is greater than ever, as fossil fuel dependence has soared and harmful emissions are being released into the atmosphere at increasingly higher rates. A viable solution to this issue is the use of microalgae for the creation of biofuels, as it holds a high concentration of lipids without requiring arable land for growth. This experiment studies downstream applications of microalgae, including how the extraction efficiency can be improved for greater lipid yield. 3-dimethyldodecylammonium propanesulfonate, myristyltrimethylammonium bromide and sodium dodecyl sulfate were used as surfactants to break down the algae cell walls and improve lipid recovery. The incubation times of the biomass in the surfactant were also studied at 0, 4.5, 24, 48 and 72 hours to more fully examine how surfactants affect the extraction of lipids. Along with this, hexane and isopropanol were used as the main extraction solvent in this experiment, but testing was done to compare these lipid yields to when ethyl acetate was used as the solvent. It was found that the MTMAB surfactant led to the greatest cell disruption, as its lipid yields were consistently higher than those of the other surfactants. Also, longer incubation times did improve the amount of lipid extracted, showing that the surfactants do have a strong effect on the cell breakdown. Finally, it was found that the ethyl acetate was a slightly more effective solvent than hexane and isopropanol in the conditions of this experiment. Overall, a stronger understanding of the wet extraction process was gained from these tests, as well as more insight into how some of the variables interact and work together during extraction.
ContributorsMartarella, Rebecca Lynne (Author) / Rittmann, Bruce (Thesis director) / Lai, Sean Yen-Jung (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12