Browsing by Author "Jackson, Andrew W."
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Item Advantages and disadvantages of microporous membranes in a hollow fiber bioreactor for space applications(2005-08) Ruiz Careri, Maria Noel; Morse, Audra; Jackson, Andrew W.Texas Tech University (TTU) works in conjunction with NASA to develop a wastewater recovery system robust enough for use on long term-space missions. Biological treatment has been the primary focus at TTU, with specific thrusts in developing a biological treatment system that may be operated with minimal crew maintenance and low energy and mass requirements. Hollow fiber membrane bioreactors (HFMBRs) may be used for biological wastewater treatment, and may be integrated with NASA’s current research developments. The goal of this research is to (a) evaluate the effect of mass transfer by the use of microporous membranes and their application for microgravity conditions; (b) compare the effect of membrane type and configuration on treatment efficiency to previous literature values; and (c) determine the amount and distribution of biofilm growth within the reactor. Therefore, the objective of this research was accomplished using a microporous HFMBR. From the experimental studies performed for this thesis it was found that the HFMBR exhibits promising use in space applications. Maximum nitrification efficiency at low loading rates and high HRTs were accomplished using the HFMBR. Therefore, characteristics such as, suitable bioreactor size and the efficiency obtained during its operation, the HFMBR offer a potential for NASA’s needs; nonetheless, developing a system with more favorable system hydrodynamics would aid to improve treatment efficiency in a HFMBRItem Advantages and disadvantages of microporous membranes in a hollow fiber bioreactor for space applications(Texas Tech University, 2005-08) Ruiz Careri, Maria Noel; Morse, Audra; Jackson, Andrew W.Texas Tech University (TTU) works in conjunction with NASA to develop a wastewater recovery system robust enough for use on long term-space missions. Biological treatment has been the primary focus at TTU, with specific thrusts in developing a biological treatment system that may be operated with minimal crew maintenance and low energy and mass requirements. Hollow fiber membrane bioreactors (HFMBRs) may be used for biological wastewater treatment, and may be integrated with NASA’s current research developments. The goal of this research is to (a) evaluate the effect of mass transfer by the use of microporous membranes and their application for microgravity conditions; (b) compare the effect of membrane type and configuration on treatment efficiency to previous literature values; and (c) determine the amount and distribution of biofilm growth within the reactor. Therefore, the objective of this research was accomplished using a microporous HFMBR. From the experimental studies performed for this thesis it was found that the HFMBR exhibits promising use in space applications. Maximum nitrification efficiency at low loading rates and high HRTs were accomplished using the HFMBR. Therefore, characteristics such as, suitable bioreactor size and the efficiency obtained during its operation, the HFMBR offer a potential for NASA’s needs; nonetheless, developing a system with more favorable system hydrodynamics would aid to improve treatment efficiency in a HFMBRItem Bioaccumulation and correspondent biochemical response of lumbriculus variegatus by exposure to fullerenes (C60)(2012-05) Wang, Jiafan; Cobb, George P.; Anderson, Todd A.; Maul, Jonathan D.; Jackson, Andrew W.; Hope-Weeks, Louisa J.Nanotechnology is one of the most popular and promising technologies in this era. It has been developed from a novel concept to an integral aspect of product advancement. Engineered nanomaterials (NMs) have been massively produced and applied into groups of products, such as automotive, defense, aerospace, electronics and computers, energy production, environmental, food production, agriculture, housing and construction, medical devices, pharmaceuticals, personal care, cosmetics. In 1985, a spherical carbon allotrope fullerene (C60) was discovered by Kroto et al. It is a foundational carbon based NM, widely applied into products due to its physical and chemical properties. However, the likelihood of direct C60 release into the environment has increased due to its applications. In recent decades, research associated with potential C60 environmental and human health risks has been emphasized. However, environmental risks of C60 are not fully understood. This research evaluated the bioaccumulation and correspondent catalase (CAT) activity change in Lumbriculus variegatus exposed to C60. With the challenge to quantify C60 in our experimental matrix, a normal shaking method was developed in this study to extract C60 effectively. Recovery results revealed 90.7 ± 4.5 % efficiency using silanized glass vessels. With relatively low cost of the supplies, this method was applied throughout the subsequent bioaccumulation study. Since few studies have emphasized C60 uptake by organisms in the environment, bioaccumulation factors have not been determined for C60 to L. variegatus. With no mortality observed in the concentration range of 0.05 to 11.33 mg C60 / kg dry weight sediment, biota-sediment accumulation factor (BSAF) was determined. For C60 aggregates in micro-size ranges (µ-C60), BSAF was 0.032 ± 0.008 at day 28, while a negligible (0.003 ± 0.006) BSAF was associated with the bigger C60 aggregates (bulk-C60). In comparison, BSAF of pyrene at day 28 (1.62 ± 0.22) was measured as a reference to determine C60 accumulation risk in the environment. Results demonstrated a lower potential for C60 accumulation in L. variegatus than pyrene. However, size effect for C60 suggests smaller aggregates can increase the accumulation in living organisms. Although C60 shows little accumulation risk in the environment, biological response corresponding to C60 exposure was observed. CAT activity was evaluated after both C60 and pyrene exposure to L. variegatus. Results illustrated a significant CAT activity change (p=0.034) at day 14 for worms exposed to C60 aggregates. This elevation was associated with the highest C60 body residue (199 ± 80 µg/kg worm tissue). Worms exposed to pyrene showed no significant CAT activity change while 600-fold higher body residues were found as compared to C60. This suggests that L. variegatus is more susceptible to C60 even through accumulation risk is relatively low. Furthermore, the relationship between C60 body residues and increased CAT activity was analyzed in linear regression to predict biological risk to L. variegatus from exposure to C60. NMs also include other compounds besides C60, such as carbon-nanotubes (CNTs) and metal-based nanoparticles. Current research has demonstrated some potential environmental and human health risks from exposure to NMs due to their special properties. In order to prevent future adverse effects from nanotechnology, an integrated governance approach that is based on scientific research and life cycle assessment is suggested to formulate effective NMs regulation. Advanced scientific research, general public education and engagement, application of well defined agenda-setting theory in public policy are all important norms in this approach to push sustainable NMs management and to prevent any unfriendly accident due to NMs exposure. In sum, this research adds to the knowledge of C60 effects on aquatic invertebrates (Lumbriculus variegatus). Governance approach suggestion is summarized and helpful in a proactive NMs management to not only aquatic ecosystems but also human health.Item Comprehensive trade study of bioreactors and advancement of membrane-aerated biological reactors for treatment of space based waste streams(2012-03) Kubista, Kyle; Jackson, Andrew W.; Morse, AudraBiological processes offer an alternative approach to treatment of waste streams for water recycling during long term space missions. The combination of biological pretreatment with downstream physiochemical processes may be able to produce potable water at a lower equivalent system mass (ESM) compared to systems composed of only physiochemical processes. Several biological configurations exist for the removal of carbon and nitrogen. To date, no studies have comprehensively evaluated the relative ESM of each system. The configurations evaluated include: 1) membrane aerated biological reactor for simultaneous nitrification/denitrification, 2) membrane aerated biological reactor for nitrification in sequence with a packed-bed reactor for denitrification and organic carbon removal, 3) a pre-carbon oxidation reactor followed by a membrane aerated biological reactor for nitrification, and 4) an extended membrane aerated biological reactor for nitrification and aerobic carbon oxidation. We report on the systems, analysis and results including a detailed discussion of the inputs of the ESM analysis, methodology for determining reactor size and mass, and the implications of each system on downstream processing and reliability. Ongoing development of microgravity compatible biological reactors is essential to develop full scale flight ready technology. Recently, the first full scale membrane aerated biological reactor (MABR) was developed and evaluated. Despite several shortcomings, the reactor laid the groundwork for future development. To further develop the full scale MABR, a counter-diffusion membrane aerated nitrification denitrification reactor, a new upgraded MABR (CoMANDR) was designed to overcome the limitations experienced by the first generation. The first generation was limited primarily by its ability to transfer oxygen to the bulk liquid and inability to make repairs due to inaccessibility to the various chambers. CoMANDR is designed to overcome oxygen transfer limitations by using a submersible membrane module (SMM) with a pressurized lumen and additional membranes (to provide increased surface area). The SMM has the ability to be completely removed from the bulk liquid chamber allowing for ease of maintenance and repair. Along with the SMM, features like unidirectional gas flow patterns, offset liquid influents, and additional membranes are incorporated into CoMANDR to address the limitations experienced in the first generation. CoMANDR has been designed, constructed and is expected to meet treatment efficiencies of 90 % dissolved organic carbon removal, 70 % nitrification, and 50 % denitrification. CoMANDR will treat mass loadings of 34 g-C/d and 44 g-N/d at a hydraulic loading rate of 40 L/d. The reactors use silicone membranes to provide surface area for bacterial attachment and to supply oxygen to the bacteria. The membranes are the most important feature of MABRs because they provide a unique biofilm stratification that allows for higher removal efficiencies. The counter-diffusion of oxygen and substrate to the bacteria create optimum biofilms. MABR technology has been studied for over 10 years and has recently been designed for full scale applications. The first full scale model experienced oxygen transfer limitations. The next full scale application intends to operate under liquid pressure and lumen pressure (conditions that have not been investigated). This paper investigates benefits of switching to thin walled membranes (1.3 mm thick) from the previously used 2.24 mm thick membranes. The thin walled membranes cannot maintain structural integrity under elevated liquid pressure. Also, the thin membranes only slightly increase the oxygen transfer rate. The thick wall membranes are recommended for the optimization of the new full scale MABR, (CoMANDR).Item Determination of groundwater velocity in-situ by using passive samplers at sediment water interface(2011-05) Ponnada, Phani; Jackson, Andrew W.; Rainwater, KenContaminated bottom sediments are one of the major sources of contaminants in surface water. The contaminants may originated from human activities, enter the subsurface environment through waste disposal, spills, and land application of chemicals. These contaminants get transported through the porewater and may enter the surface water from the bottom sediments. Establishment of effective remediation systems and protection of public health rely on the ability to estimate the mass flux of the contaminants to surface water. The mass flux is a function of porewater velocity, retardation factor, and degradation coefficient. In this research, passive sampler (peepers) were used to determine the groundwater velocity insitu when the mass flux of the contaminants to surface water was low. This study suggested that the ability of the samplers to accurately capture produced tracer profiles depends on the velocity of the flow and equilibration time of the peeper. Low velocities allowed greater time for the sampler to equilibrate, approaching steady state with the pore water. The sampler was able to serve as a tracer source but was not able to provide a large enough flux of tracer to allow downstream locations to approach the source concentration. Regardless, steady state profiles developed rapidly, likely due to the rapid increase in area available for diffusional flux with distance from the source and the limited flux of source from the sampler cell. A sensitivity analysis indicated that, as expected, diffusional transport dominated at very low velocities and that the source dimensions were the critical determinant of the tracer concentration profile shape. Overall, these studies suggest that it may be possible to differentiate groundwater velocity, but that samplers with very low depths would be required (<0.5cm).Item Experimental Studies and Mathematical Modeling of Simultaneous Nitrification/Denitrification in Membrane-Aerated Biofilm Recators(2010-12) Landes, N; Jackson, Andrew W.; Morse, Audra; Moore-Kucera, Jennifer; Long, KevinMembrane-aerated biofilm reactors (MABRs) have emerged as a potential nitrogen removal technology for high-strength, nitrogen dominant waste streams (TOC:N<1, NH4+ > 500mg/L). In particular, the unique properties of a MABR are well suited for extreme and/or isolated environments with carbon limited wastes such as a lunar habitation scenario. Among many other features, the ability of MABRs to degrade carbonaceous and nitrogenous pollutants concomitantly via simultaneous nitrification and denitrification (SND) in a single-stage vessel has posed this technology as a well-suited candidate for space-based water reuse applications. Relatively untouched by current MABR research, nitrogen dominant waste streams have been deemed outside the range for significant SND in a MABR without the supply of exogenous consumables; however, experimental research has not been conducted in order to confirm or disprove this hypothesis. The goal of this current work was to explore the performance limits of treating a space-based waste stream with the MABR technology using experimental studies and mathematical modeling efforts. The experimental studies entailed investigating the performance of a traditionally designed MABR and a modified MABR (mMABR). The mMABR combined oxygen permeable membranes in tandem with inert attachment media theoretically supporting nitrification on the former and denitrification on the latter. The traditionally designed MABR reported average carbon and total nitrogen (TN) removal rates as high as 0.33 g-C/m2-d and 0.14 g-N/m2-d, respectively, whereas the mMABR achieved mean carbon and TN removal rates reaching 0.26 g-C/m2-d and 0.22 g-N/m2-d, respectively. The most notable difference between the two reactors was the ability of the mMABR to support denitrification, which was attributed to the mMABRs combination of co- and counter-diffusion biofilms. The mathematical modeling study aimed to identify the inherent differences that could be propagated by the range of assumed nitrification and denitrification biochemical pathways for one-dimensional membrane-aerated biofilm models. The overarching conclusion reached as a result of this study was that mathematical simulation results vary based upon the assumed biopathway applied to the model. The results of this study were used to understand the underlying processes that occurred during the MABRs treatment of a space-based waste.Item Heterogeneous production of perchlorate and chlorate by ozone oxidation of Cl-(2011-08) Wang, Sixuan; Jackson, Andrew W.; Anderson, ToddABSTRACT Perchlorate (ClO4-) is proved to be of atmospherically produced, it found to be widely spread in environment although in a low concentration. Studies had demonstrated atmospheric ClO4- formation and mechanism of ClO4- formation by UV irradiation and ozone oxidation of Cl- and oxy-chlorine species. They also analyzed environmental condition impacts on perchlorate formation. However, little information is known about ozone oxidation of dry Cl-. This study mainly focused on factors that impact ClO4- formation through ozone oxidation of chloride in the dry condition. Reaction time, mass of initial Cl-, reactor surface area, humidity in the reactor, and the physical form of Cl- are factors that been systematically evaluated in this experiment. The mass of ClO4- formed in the reactor increased roughly linearly (R2 = 0.98; R2 = 0.83) with respect to reaction time. ClO4- mass did not consistently vary with an increase in Cl- mass while ClO3- increased 3 order of magnitude (0.043 μg- 37.93 μg) over the 4 order range of Cl- masses reacted. ClO4- formed mass in the humidity system was similar with it produced in the dry system, however, ClO3- mass increased by 2 orders of magnitude in humidity system compared to dry system. The increase of glass surface area could increase the production of ClO4- in this experiment, it seems like glass tube surface could act as catalyst to accelerate ClO4- formation. ClO4- mass produced by HCl gas was relatively the same with it produced by NaCl salts, so, Cl physical phase do not have impact on ClO4- production.Item Occurrence, Distribution, And Speciation of Arsenic in the Southern High Plains Aquifer System(2010-12) Venkataraman, Kartik; Rainwater, Ken; Jackson, Andrew W.; Ridley, Moira K.Significant levels of arsenic have been detected in the groundwater of the Southern High Plains. The potential sources include atmospheric deposition, the use of agricultural defoliants and natural subsurface geochemical interactions. To identify the source of arsenic, groundwater and soil samples were collected from sites spread over 18 counties in the Southern High Plains. Total arsenic and its inorganic species were quantified along with commonly occurring and related cations and anions such as iron, manganese and sulfate. Correlation studies were conducted to understand the variation of arsenical species with related parameters. A geochemical modeling tool, MINTEQ was used to predict the speciation of arsenic and compare these results with lab analyses. The distribution of arsenic in the soil profiles tested indicated a positive correlation with depth. The highest concentrations were found close to the water table while the upper soil layers had low to non-detect concentrations. In the groundwater samples, arsenic concentration and speciation varied significantly between sites. As (III) was found to be the dominant species in over 80% of the samples. MINTEQ speciation forecasts compared favorably with a majority of the groundwater analyses. Very little evidence of atmospheric deposition exists and the sources of arsenic are likely anthropogenic land sources in the shallow subsurface and natural geologic processes in the deeper subsurface.Item The impact of biological pretreatment on reverse osmosis performance in space flight applications(2007-12) Crawley, Jason; Morse, Audra; Jackson, Andrew W.; Song, Lianfa; Anderson, ToddRO is a treatment technology likely to be used for the recovery of wastewater on board long duration, manned space flights. As with terrestrial RO applications, concentration polarization and fouling lead to decreasing productivity and increasing energy demands with time. These problems are further complicated in a closed loop environment that demands a high level of recovery and quality. Physiochemical and biological pretreatment options can enhance the performance of the RO system. Physiochemical pretreatment is not always desirable in the application of long duration space flight because the transport and stowage of consumables can be cost prohibitive. Also, the transport and stowage of hazardous materials such as strong acids and bases is not desirable. Biological pretreatment is a low energy option that requires only a limited supply of consumables. Additionally, biological pretreatment is a proven terrestrial technology that is well understood. To determine the degree to which the incorporation of biological treatment enhances RO performance, a series of bench scale experiments were performed. The RO performance was measured in terms of permeate flux decline, solute rejection, and flow resistances. A mass balance and observed solute concentrations also helped to determine the fate of selected solutes. The gel layer model was used to evaluate the permeate flux for each of the experiments. Observed resistances also indicate that biological pretreatment alleviates the degree of fouling. Results indicate that enhanced urea hydrolysis, pH decrease, and carbon oxidation serve as the primary benefits of biological pretreatment.Item Uptake, distribution, and fate of RDX and MNX in dark green bulrush plants(2009-05) Sanka, Sameera; Jackson, Andrew W.Constructed wetlands are emerging as a promising technology for remediation of water contaminated with low RDX concentrations. A study on the ability of dark green bulrush (Scirpus atrovirens), a wetland plant, to uptake RDX will help to find its utility in constructed wetlands. In this study RDX uptake in actively growing bulrush was evaluated over a sixteen week period at different RDX exposure levels (0.5, 1, 3 mg/l). Plant samples along with influent water, effluent water, and final soil samples were analyzed for RDX, MNX, TNX and DNX. After 16 weeks of exposure and sacrificing 7 of the 9 sets of plants, exposure to RDX was discontinued. The remaining two sets of plants were sacrificed at weeks 19 and 22. RDX concentration in plants substantially decreased during the period of no exposure. About 97% of the RDX concentration in the top third and 75% in bottom and middle thirds of the leaf was lost during the six weeks of cessation to RDX exposure. RDX uptake in mature bulrush was also evaluated over a six week period at 1 mg/l exposure concentration. RDX was detected at higher concentrations in the top third of the leaf when compared to middle and bottom thirds in actively growing as well as in mature bulrush. MNX was detected in 99% of plant and soil samples. DNX and TNX were detected in few bottom thirds of the leaf and root portions of the bulrush in very low concentrations (0.003 to 0.03 mg/kg), but were very rarely detected in other samples. MNX uptake in mature bulrush was also evaluated over a five week period at 0.5 mg/l exposure concentration. Unaccounted MNX in the treatment systems of bulrush exposed to 0.5 mg/l MNX was around 59% compared to unaccounted RDX of 19, 23 and 38% respectively for 0.5, 1, 3 mg/l RDX exposure treatment systems. No bleaching or necrosis was observed during the course of the experiment in any of the plants. The results are suggesting that RDX exposure up to 3.0 mg/l does not have any adverse effects on bulrush. RDX accumulation in actively growing bulrush increased with time but in mature bulrush RDX accumulation remained more or less constant.Item Utilization of nitrogen from surface and subsurface applied wastewater(2012-12) Francis, Richard; Fedler, Clifford B.; Jackson, Andrew W.; Zartman, Richard E.A pilot test was conducted to determine the difference in nitrogen removal between surface and subsurface applied wastewater systems in soil columns topped with Bermuda grass (cynodon dactylon). Six columns were set up, three with water applied to the surface, and three with water applied in the subsurface through a positive-displacement pump. The concentration of nitrogen was kept uniform within the system with variable loading rates to ensure leaching occurred. The water added and the water leached were tested with HACH(R) test-n-tube kits for total nitrogen, ammonia, and nitrate-N concentrations. A statistical analysis was performed to determine if there were any significant differences in the concentrations of these constituents in the effluents between the two systems. The analysis showed that there was virtually no difference (Pr>F = 0.657) between the two systems in regards to percent of nitrogen removed from the system. The test also showed that subsurface applied systems performed marginally better that surface applied systems in total nitrogen and nitrate-N concentrations in the effluent. There were also virtually no differences (Pr>F = 0.209) in the total Kjeldahl Nitrogen concentrations in the plant tissue.