Browsing by Author "Morse, Audra"
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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 Biological treatment and biofouling in membrane treatment systems(2012-05) Vercellino, Tony; Morse, Audra; Reid, Ted W.; Hamood, Abdul N.; Song, LianfaAs the world’s population increases, the demand for water will increase accordingly. The corresponding demand for water puts a strain on the available sources of water and the technologies to reclaim water from non-potable sources. The use of membranes is quickly emerging as the prominent treatment technique for water purification. While the increase in use of membrane technology is providing the water that the world demands, operational problems such as fouling are limiting the potential of these membrane processes. Fouling due to biological growth, otherwise known as biofouling, is the foremost form of fouling that affects current membrane treatment systems. The use of covalently attached organo-selenium as a surface modification to reverse osmosis membranes was studied as a potential biofouling inhibition agent. The efficacy of the organo-selenium surface treatment was tested within a flow-cell system which exposed the membrane samples to high nutrient medias at low-flow, simulating a worst-case condition for biofouling to occur at the membrane surface. The surface treatment was also tested within a bench-scale reverse osmosis system, where the membranes were exposed to normal operating conditions for a reverse osmosis system. Within the low-flow system, the organo-selenium surface treatment was able to achieve a range of 2.01 to 3.98 logs of inhibition of total biomass. Within the RO system, the organo-selenium surface treatment was able to achieve between 2.2 and 3.8 logs of total biomass inhibition. However, when the polypropylene feed spacer also received the surface treatment, total biomass inhibition was increased to 5.9 logs.Item Characterization and optimization of a biosand filter(2012-05) Kennedy, Timothy; Morse, Audra; Anderson, Todd A.; Hernandez, Emilio A.More than 800 million people worldwide do not have access to clean drinking water. The number though high, has recently been reduced thanks to technologies like the biosand filter (BSF), an intermittently operated household scale slow sand filter. To date, studies have documented removal of microbiological water quality parameters and some chemical parameters. Few studies have sought to improve upon the current design of the BSF, examine its limits, or investigate its ability to remove emerging contaminants. The goal of this work was to examine a modification of the BSF, determine its operating limits, and investigate the ability of a BSF to remove emerging contaminants. Modification of the BSF was achieved by decreasing the outlet spout diameter, increasing the BSF hydraulic retention time. Turbidity, fecal coliforms (FC), dissolved oxygen (DO), pH, total organic carbon, and nitrogen data were measured in the influent and effluent water. Overall, the modification did not significantly improve water quality over the course of the experiment, though significantly greater removal of FC was observed during the startup period when comparing the 0.25” BSF to the control (unmodified) BSF. Initial startup, recovery after cleaning, maximum number of users served, and an extended pause period of the BSF were examined using the same water quality parameters as the optimization study to determine the BSFs operational limits. Results of this study indicated that the initial startup may take up to 27 days to achieve 1 log reduction of fecal coliforms, while only 17 days were needed after the first cleaning of the BSF. The maximum number of users effectively served was determined to be six, as at volumes greater than this water quality was significantly worse. Water quality was similar to the recovery period when the extended pause period of 1 week was examined, reiterating that the BSF must be used multiple times per week for best results. The removal of three endocrine disrupting compounds, estrone (E1), estriol (E3), and 17α-ethinyl estradiol (EE2) was examined by spiking a high concentration (5 mg/L) into daily BSF feed water. Results indicate the percent removal efficiency in the BSF is similar to that in slow sand filters, though the mass removal rate in the BSF was orders of magnitude greater. When the effluent was treated with household bleach, removal increased based upon Cl- dose. The BSF is a valuable technology for improving water quality, and should be used along with disinfection to protect user 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 EVALUATION AND INHIBITION OF BIOFILM ATTACHMENT TO MEMBRANE SURFACES IN WATER AND WASTEWATER TREATMENT SYSTEMS(2010-12) Low, Darryl; Morse, Audra; Hamood, Abdul N.; Reid, Ted W.; Song, LianfaAs engineers’ understanding of the biological treatment systems in water and wastewater systems increased, advanced technologies have emerged. These included combining biological systems with other treatment systems such as membrane technologies. The overall objective of this research was to evaluate the impacts of bacterial attachment to membranes during treatment operations and propose an antimicrobial coating to maximize membrane performance. Membranes from a small scale, membrane aerated biological unit were removed and analyzed for continued performance after an extended operational period. Afterwards, a selenium based antimicrobial coating was developed to prevent microbial attachment without harming membrane performance. This coating was applied to reverse osmosis membranes and the coating’s efficacy to prevent biofilm growth on the reverse osmosis membrane surface was investigated. Ultimately, the selenium coating displayed a strong inhibition against bacterial attachment and biofilm formation. Selenium’s capability to catalytically generate superoxide molecules was effective in damaging bacterial cell membranes resulting in lysis. Both Gram positive (S. aureus) and Gram negative (E. coli) bacteria showed high susceptibility to the superoxide attack. Attachment utilizing the selenocystamine molecule via peptide bond to a modified membrane surface was selected as the desired attachment method. Selenocystamine allowed for the RO membrane to maintain its higj permeate flux without overly diminishing membrane rejection. Attachment of selenium to membrane surfaces may be a valuable technology to allow for continuous performance even in the harsh operating conditions present in biological reactors.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 Exploiting synergy in animal co-product bisolids processing: the cactus project(2006-05) Pasupuleti, Divya; Morse, Audra; Shelly, Dennis C.The current project is a feasibility study prepared for the Dumas Economic Development Corporation in Cactus, Texas for the purpose of evaluating the feasibility of constructing a facility that processes leather wastes to produce useful products. The project aims at developing a zero discharge strategy by fully utilizing the wastes from the leather making industry and converting them into value-added products. The model of the comprehensive animal co-product biosolids processing facility consists of six processing units namely the tannery, the keratin unit, the collagen unit, the biodiesel unit, the modular agriculture unit, and the biogasification unit. All the above units are linked to each other in such a way that the waste produced by one unit is used as input to another unit, leading to zero waste discharge. Simulation models of all the units were developed using the SuperPro Designer software. The tannery processes raw goatskins and converts them into wet blue leather. In the process, the tannery generates wastes like hair pulp, fleshing grease, wastewater, and waste biosolids. The hair sludge and fleshing grease produced from the sanitization of hides in the tannery are sent to the keratin unit and biodiesel unit to obtain useful products like keratin and bio-diesel, respectively. The collagen unit is used to produce gelatin, protein, and basic chrome sulfate from wet blue shavings. The chrome sludge produced in this process is sent to the tannery to enable sanitization of the hides. The wastewater produced from all the above processes is sent to a modular agriculture unit, to grow duckweed and baitfish. Virtually all the waste biosolids are sent to a biogasification unit to produce power, steam, and ash. The annual operating costs for all the units in the facility were determined based on current prices of equipment, raw materials, labor, and utilities. The revenues obtained from the product sales of each unit determined the profitability. The profítability of the entire facility was determined based on the economics of the individual units. The total capital investment on the facility was approximated at $8,890,000. The total annual operating costs were estimated to be $7,466,000. The total annual revenues were found to be $9,581,000. The total gross profit obtained from the entire facility was estimated to be $2,115,000. The total net profit was found to be $1,763,000. The payback time is just 5 years. The results of the study indicate that the Cactus facility provides economic benefits and reduces environmental impact by eliminating the discharge of wastes.Item Fate and effect of amoxicillin in space and terrestrial water reclamation systems(Texas Tech University, 2003-05) Morse, AudraAs NASA strives towards long-term manned space travel, wastewater recycling will be necessary to provide adequate water. Contaminants, including pharmaceuticals, may be present if astronauts take medications. The overall effects of pharmaceuticals, specifically antibiotics, in recycled wastewater are unknown. One concern is the development of antibiotic resistance by pathogenic bacteria. Additionally, the effects of antibiotics on biological wastewater recycling systems have not been quantified. The overall objective of this research was to determine the fate of amoxicillin in wastewater reclamation systems. Wastewater recycling systems investigated included both systems and feeds typical of space applications located at Johnson Space Center (JSC) and Texas Tech University (TTU), as well as one terrestrial wastewater recycling system (City of Lubbock's Water Reclamation Plant). The overall objective of this research was further divided into three sub-objectives to determine (1) the fate of amoxicillin in JSC's and TTU's water recovery system; (2) the effects of amoxicillin on treatment efficiency; and (3) the development of antibiotic resistance by the microorganisms in the treatment system. The results of this study indicate amoxicillin is easily removed in a biological wastewater treatment system. In addition, the post-processing units were capable of removing amoxicillin. Due to the low concentrations of amoxicillin in the JSC-WRS and TTU-WRS, amoxicillin did not affect the treatment efficiency of the system although if concentrations increased above 10 mg/L some inhibition may be possible. Organisms in all systems were resistant to the antibiotics investigated, including many beta-lactam antibiotics and a beta-lactam, beta-lactamase inhibitor combination (amoxicillin with clavulanic acid). In both systems, resistance was present in the system before initiating the amoxicillin experiment. The antibiotic resistance patterns of the LWRP varied monthly; heterotrophic bacteria were resistant to most of the antibiotics investigated during the nine month study. In summary, amoxicillin will not accumulate in biological wastewater treatment systems and treatment efficiency will be unaffected by amoxicillin presence; however, microorganism may develop a resistant to amoxicillin if they are not already resistant to amoxicillin.Item Interdisciplinary studies portfolio(2012-05) Weinert, Philip M.; Morse, Audra; Davis, Donna F.; Heuman, Amy N.For completion of my Masters degree I must complete a portfolio comprised of specific works of which I think would show growth and development as a collegiate scholar. I have chosen for my portfolio a composition of a case study analysis, research proposal, a term paper, and an overall reflection to show the growth I have developed over the last two and a half years. The three papers which I have included I have written for several of the many graduate courses I have taken while achieving my Masters of Science in Interdisciplinary Studies.Item Occurrence and fate of synthetic musk fragrances in effluent and non-effluent impacted environments: Detection in environmental matrices and implications for water policy(2011-08) Chase, Darcy; Anderson, Todd; Morse, Audra; Cobb, George P.Synthetic musk fragrances (SMFs) are considered micropollutants and can be found in various environmental matrices near wastewater discharge areas. These emerging contaminants are often detected in wastewater at low concentrations. They are continuously present and, therefore, constitute a constant exposure source. Objectives of this study were to investigate the environmental fate, transport, and transformation of SMFs. Occurrence of six polycyclic musk compounds (galaxolide, tonalide, cashmeran, celestolide, phantolide, traseolide) and two nitro musk compounds (musk xylene and musk ketone) were monitored in wastewater, various surface waters and their sediments, as well as groundwater, soil cores, and plants from a treated wastewater land application site. Specifically, samples were collected quarterly (1) from a wastewater reclamation plant to determine initial concentrations in wastewater effluent, (2) from a storage reservoir at a land application site to determine possible photolysis before land application, (3) from soil cores to determine the amount of sorption after land application, (4) from a lake system and its sediment to assess degradation, and (5) from non-effluent impacted local playa lakes and their sediments to assess potential sources of these compounds. Recently an innovative technique, stir-bar sorptive extraction (SBSE), was developed to extract organic contaminants from a variety of matrices. This method may lower detection limits and provide efficient analyses needed to detect SMFs in exclusive matrices such as those in this study (plants from a land application site and blood samples from ring-tailed lemurs (Lemur catta) in a remote location). Preliminary methods herein described were for using SBSE as a method to detect traceable concentrations in matrices not likely to accumulate high quantities of SMFs. Because SMFs are able to transport through different matrices along a remote pathway (i.e., from consumer product to wastewater to surface water or soil to groundwater then drinking water and even air and biota), SBSE is a method that can be used to validate the occurrence of SMFs and again affirm their ubiquitous nature. All samples were analyzed using gas chromatography coupled with selected ion mass spectrometry. Data indicated that occurrence of SMFs in effluent-impacted environments was detectable at ng/L and ng/g concentrations which decreased during transport throughout wastewater treatment. However, unexpected concentrations, ng/L and ng/g, were also detected in playa lakes not receiving treated effluent. Additionally, soil cores from land application sites had ng/g concentrations. Galaxolide and tonalide were consistently found in all environments, whereas various musks were found in non-effluent impacted environments. Galaxolide was also detected in exclusive matrices using SBSE techniques. Information on occurrence is critical to assessing exposure to these potentially endocrine disrupting compounds. Such information could provide a scientific framework for establishing the need for environmental regulations. Greywater use is a potential solution for addressing water shortages and sustainability. As water reuse practices increase, concerns about water quality should be addressed. The U.S. National Pollutant Discharge Elimination System (NPDES), under the Clean Water Act, limits the amount of discharged pollutants from wastewater treatment facilities in order to maintain water quality. Emerging organic pollutants not completely eliminated during treatment processes are not regulated by NPDES. These emerging contaminants may have an impact on the environment. Research on the occurrence, fate, and toxicity of emerging organic pollutants, specifically pharmaceuticals and personal care products (PPCPs), is needed to provide a scientific framework upon which appropriate environmental regulations could be established. Refining NPDES policy can address PPCPs found in wastewater, and lead to better monitoring and implementation of enhanced wastewater treatment. Integrative approaches that bridge scientific understanding with policy making can lead to healthier watersheds, ultimately improving the Clean Water Act goals.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.