12 research outputs found

    Design of a Nutrient Reclamation System for the Cultivation of Microalgae for Biofuel Production and Other Industrial Applications

    Get PDF
    Microalgal biomass has been identified as a promising feedstock for a number of industrial applications, including the synthesis of new pharmaceutical and biofuel products. However, there are several economic limitations associated with the scale up of existing algal production processes. Critical economic studies of algae-based industrial processes highlight the high cost of supplying essential nutrients to microalgae cultures. With microalgae cells having relatively high nitrogen contents (4 to 8%), the N fertilizer cost in industrial-scale production is significant. In addition, the disposal of the large volumes of cell residuals that are generated during product extraction stages can pose other economic challenges. While waste streams can provide a concentrated source of nutrients, concerns about the presence of biological contaminants and the expense of heat treatment pose challenges to processes that use wastewater as a nutrient source in microalgae cultures. The goal of this study was to evaluate the potential application of ultrafiltration technology to aid in the utilization of agricultural wastewater in the cultivation of a high-value microalgae strain. An ultrafiltration system was used to remove inorganic solids and biological contaminants from wastewater taken from a swine farm in Savoy, Arkansas. The permeate from the system was then used as the nutrient source for the cultivation of the marine microalgae Porphyridium cruentum. During the ultrafiltration system operation, little membrane fouling was observed, and permeate fluxes remained relatively constant during both short-term and long-term tests. The complete rejection of E. coli and coliforms from the wastewater was also observed, in addition to a 75% reduction in total solids, including inorganic materials. The processed permeate was shown to have very high concentrations of total nitrogen (695.6 mg L-1) and total phosphorus (69.1 mg L-1). In addition, the growth of P. cruentum was analyzed in a medium containing swine waste permeate, and was compared to P. cruentum growth in a control medium. A higher biomass productivity, lipid productivity, and lipid content were observed in the microalgae cultivated in the swine waste medium compared to that of the control medium. These results suggest that, through the use of ultrafiltration technology as an alternative to traditional heat treatment, agricultural wastewaters could be effectively utilized as a nutrient source for microalgae cultivation

    Methods for the analysis of low-Z plasma facing surfaces in magnetic fusion applications

    No full text
    A number of advances in the design and operating performance of magnetic fusion devices have been made in recent decades. While the optimization of reactor components and magnetic topologies have led to considerable improvements in plasma density, temperature, and confinement time, research also suggests that materials selection in plasma-facing components (PFCs) can also have a substantial impact on plasma performance. Within the plasma-material interaction (PMI) community, the application of low-Z materials on wall components is of particular interest. In order to better understand the behavior of various low-Z systems, two PFC studies are described herein. The goals of these studies were to: (1) better understand material migration in boronized graphite wall tiles via the ex-vessel characterization of the B-O-C layer in exposed graphite samples, and (2) explore issues relating to the impacts of handling and processing on a liquid phase Sn-Li binary alloy. The National Spherical Torus Experiment Upgrade (NSTX-U) has been used to investigate the effect of wall tile surface conditioning on plasma performance during operation. Previous campaigns have demonstrated the enhanced suppression of edge-localized modes (ELMs) and reduced divertor recycling when wall tile conditioning via boronization was performed, and high confinement (H-mode) operating conditions were routinely achieved during operation after conditioning. In order to better understand the impact of surface conditioning and subsequent plasma exposure on wall materials, cored sample of the exposed NSTX-U wall tiles were obtained and their surface chemistry was analyzed. The boronized NSTX-U samples were analyzed using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and Rutherford backscattering spectrometry (RBS). In addition, variations in surface morphology in each tile were mapped using a 3D laser scanning confocal microscope. Similar to the pure low-Z coatings used in the NSTX-U device, tin-lithium is a low melting-point eutectic that has been identified as a material with favorable performance in plasma material interaction (PMI) studies. The Sn-Li eutectic is a more stable alternative to pure lithium that provides a lower rate of evaporative flux due to the presence of tin while experiencing the bulk segregation of lithium to the surface of the material in the liquid phase. This surface segregation prevents the high-Z tin from entering the plasma. While the alloy is of considerable interest to the PMI community, few studies have directly documented the presence of a pure lithium surface in a tin-lithium melt. In order to expand the existing body of knowledge in this area, samples of an 80% Sn‚ÄĒ20% Li eutectic were pre-cast and subsequently melted and analyzed in the Angle-Resolved Ion Energy Spectrometer (ARIES) at Sandia National Laboratories.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste

    Methods for the analysis of low-Z plasma facing surfaces in magnetic fusion applications

    No full text
    A number of advances in the design and operating performance of magnetic fusion devices have been made in recent decades. While the optimization of reactor components and magnetic topologies have led to considerable improvements in plasma density, temperature, and confinement time, research also suggests that materials selection in plasma-facing components (PFCs) can also have a substantial impact on plasma performance. Within the plasma-material interaction (PMI) community, the application of low-Z materials on wall components is of particular interest. In order to better understand the behavior of various low-Z systems, two PFC studies are described herein. The goals of these studies were to: (1) better understand material migration in boronized graphite wall tiles via the ex-vessel characterization of the B-O-C layer in exposed graphite samples, and (2) explore issues relating to the impacts of handling and processing on a liquid phase Sn-Li binary alloy. The National Spherical Torus Experiment Upgrade (NSTX-U) has been used to investigate the effect of wall tile surface conditioning on plasma performance during operation. Previous campaigns have demonstrated the enhanced suppression of edge-localized modes (ELMs) and reduced divertor recycling when wall tile conditioning via boronization was performed, and high confinement (H-mode) operating conditions were routinely achieved during operation after conditioning. In order to better understand the impact of surface conditioning and subsequent plasma exposure on wall materials, cored sample of the exposed NSTX-U wall tiles were obtained and their surface chemistry was analyzed. The boronized NSTX-U samples were analyzed using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and Rutherford backscattering spectrometry (RBS). In addition, variations in surface morphology in each tile were mapped using a 3D laser scanning confocal microscope. Similar to the pure low-Z coatings used in the NSTX-U device, tin-lithium is a low melting-point eutectic that has been identified as a material with favorable performance in plasma material interaction (PMI) studies. The Sn-Li eutectic is a more stable alternative to pure lithium that provides a lower rate of evaporative flux due to the presence of tin while experiencing the bulk segregation of lithium to the surface of the material in the liquid phase. This surface segregation prevents the high-Z tin from entering the plasma. While the alloy is of considerable interest to the PMI community, few studies have directly documented the presence of a pure lithium surface in a tin-lithium melt. In order to expand the existing body of knowledge in this area, samples of an 80% Sn‚ÄĒ20% Li eutectic were pre-cast and subsequently melted and analyzed in the Angle-Resolved Ion Energy Spectrometer (ARIES) at Sandia National Laboratories.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste

    Porphyridium cruentum Grown in Ultra-Filtered Swine Wastewater and Its Effects on Microalgae Growth Productivity and Fatty Acid Composition

    No full text
    Microalgae have been extensively tested for their ability to create bio-based fuels. Microalgae have also been explored as an alternative wastewater treatment solution due to their significant uptake of nitrogen and phosphorus, as well as their ability to grow in different water types. Recently, there has been significant interest in combining these two characteristics to create economic and environmentally friendly biofuel using wastewater. This study examined the growth and lipid production of the microalgae Porphyridium (P.) cruentum grown in swine wastewater (ultra-filtered and raw) as compared with control media (L−1, modified f/2) at two different salt concentrations (seawater and saltwater). The cultivation of P. cruentum in the treated swine wastewater media (seawater = 5.18 ± 2.3 mgL−1day−1, saltwater = 3.32 ± 1.93 mgL−1day−1) resulted in a statistically similar biomass productivity compared to the control medium (seawater = 2.61 ± 2.47 mgL−1day−1, saltwater = 6.53 ± 0.81 mgL−1day−1) at the corresponding salt concentration. Furthermore, no major differences between the fatty acid compositions of microalgae in the treated swine wastewater medium and the control medium were observed. For all conditions, saturated acids were present in the highest amounts (≥67%), followed by polyunsaturated (≤22%) and finally monounsaturated (≤12%). This is the first study to find that P. cruentum could be used to remediate wastewater and then be turned into fuel by using swine wastewater with a similar productivity to the microalgae grown in control media
    corecore