The lack of access to clean electricity and water in developing nations has given importance to the development of low-cost, widely applicable energy technologies. Microbial fuel cells are being explored as potential sources of clean electricity. A microbial fuel cell (MFC) is a device, in which bacteria produce electrons by oxidizing organic material, which are shuttled from the anode to the cathode, producing a current; the only byproducts of this process are respiratory waste in the form of water and carbon dioxide. Although significant advances have been made in optimizing MFCs for power output, power outputs are not always reproducible, and most importantly, MFC performance is not yet predictable under different operating conditions. These two challenges are prerequisites to the commercialization of MFC technology. In this study, a single-chamber MFC employing E.coli K12 as the biocatalyst was used to optimize power outputs and operating conditions, and demonstrate the reproducibility of MFC data. This prototype MFC was able to produce a maximum of 100 mW/m3 of reactor volume, at optimized electrode distance (2.54 cm), ionic strength of 0.5, and using a culture electrochemically activated for three generations. The data was reproducible with maximum standard errors of ± 15 mW/m3. Using this basis, a new fuel cell design was introduced, in which the anode electrode surface was increased and reactor volume was decreased. To investigate the prediction of MFC performance under different operating conditions, the new MFC model was used in a 3-level, three factor (substrate concentration, ionic strength, and medium pH) Box-Behnken experimental design. A statistical model was constructed, which could reliably predict power outputs in the MFC with less than 10% error. The statistical model optimized operating conditions in the MFC (pH 9, NaCl concentration of 15 g/L, substrate concentration of 5 g/L), corresponding to a power density of 1027 mW/m3. The effect of dimensionless quantities on MFC performance was briefly investigated: higher Schmidt values resulted in lower power densities, indicating the negative impact of increased viscosity on mass transport; all Reynolds values resulted in washout, but increases in power densities were still observed during flow regime transitions; finally, power decreased with increase Peclet values, indicating that convective mass transport was removing substrate and bacteria faster than reactions could occur. The results of this study contribute to the scale-up of MFC technology based on the prediction of MFC performance, the ability to produce repeatable results, and the demonstration of MFC performance as a function of dimensionless, scale independent parameters. This work furthers scholarship in a crucial area of MFC research, necessary for the technology's widespread application. / Le manque d'accès à l'électricité et à l'eau potable parmi les pays en développement augmente l'importance de l'innovation en domaine de technologie verte et énergie renouvelable, afin d'introduire une technologie qui est applicable à grande échelle. En tant que tel, les piles à combustible microbien sont présentement recherchées. Une pile à combustible microbien (PCM) est un appareil dans lequel les bactéries sont utilisées à oxyder les molécules organiques, afin de libérer des électrons; ces électrons sont transférés hors de la cellule à l'anode jusqu'au cathode, produisant le courant. Les seuls sous-produits de ce processus sont de l'eau et du dioxyde de charbon. Quoique le domaine de recherche en PCM ait avancé, notamment en optimisation de la production d'électricité, les puissances de sortie ne sont pas toujours reproductibles de façon fiable, et il est présentement impossible de prédire la performance des PCM aux conditions opératoires différentes. La résolution de ces deux défis est considérée parmi les questions le plus importantes de la recherche en PCM. Pendant cette étude, une PCM à un seul compartiment, à l'emploi de l'E. coli K12 comme catalyseur biologique, a été construite au but d'optimiser la production d'électricité et les conditions opératoires, et pour démontrer des données reproductibles. Ce prototype était capable de produire une puissance maximale de 100 mW/m3 (volume du réacteur), aux conditions suivants : espace de 2.54 cm entre les électrodes, force ionique de 0.5, et culture électrochimique de troisième génération. Les données étaient reproductibles avec erreur minimale (± 15 mW/m3). Étant donné ces résultats, un prototype nouveau, de moins volume, était introduit, avec un anode de graphite en format pinceau. Une plan d'expérience Box-Behnken (trois facteurs de trois niveaux chaque) était conçu afin de prédire la performance de la PCM aux conditions opératoires différentes (concentration de substrat, concentration de NaCl, et pH). Un modèle statistique était construit, capable de prédire la puissance électrique de la PCM avec erreur minimale (moins de 10%). Selon le modèle, les conditions opératoires optimales (pH 9, concentration de NaCl 15 g/L, concentration de lactose 5 g/L) ont correspondu à une puissance de 1027 mW/m3. L'effet des quantités sans dimensions sur la performance de PCM était recherché brièvement : lorsque le valeur de Sc augmentait, la puissance décroisse, indiquant l'effet négatif de la viscosité élevée sur le transport de la masse en PCM; les valeurs de Re examinés ont tous résulté en dilution extrême de la culture en PCM, mais l'accroissement de puissance été observé pendant les transitions d'un régime d'écoulement à l'autre; finalement, la puissance électrique décroissaient lorsque le valeur de Pe augmentait, un effet qui indique que la transport de masse en PCM était trop fort. Les résultats de cette étude montent les efforts en commercialisation des PCM, ayant contribué les données sur la prédiction de la performance des PCM qui sont reproductibles, et la description de relations entre la performance des PCM et les quantités sans dimension. La recherche présentée ici avance un parti crucial du domaine de PCM.

Abstract Not Available.

The current nanotechnology boom necessitates timely research into the health and environmental impacts of nanomaterials to enhance their eco-responsible manufacture, use, and disposal. Using the water-insoluble C60 as a model nanomaterial, the potential environmental impacts of a C60 water suspension, termed nC60, are here assessed with bacteria as a receptor. nC60 was evaluated for antibacterial activity, antibacterial mechanisms, impact on natural microbial systems, and potential disinfection applications. nC60 is a potent antibacterial agent when tested against pure cultures of different bacteria. Whereas neither light nor oxygen affects its potency, toxicity is increased by smaller particle size and mitigated by salts which promote precipitation. In complex environments, toxicity was lessened by salts or by natural organic matter that sorbed or coated nC60, reducing its bioavailability. The applicability of nC60 as a disinfectant is thus limited to situations with limited organic matter and debris (e.g., drinking water disinfection); it is not recommended for antibiofouling coatings where precipitating debris occluded the nC60 coating and promoted biofilm formation. In contrast to literature showing nC60 -generated reactive oxygen species damaging eukaryotic systems, this research shows that nC60 behaves as an oxidant upon direct contact with the cell, leading to uncoupled respiration and/or damaged respiratory proteins. The methods that were previously used to detect ROS-mediated damage are shown to be ambiguous and susceptible to interference by nC60, implying that the evidence of ROS-mediated oxidative stress needs to be re-evaluated. Overall, this research reflects an overall image of preventable or negligible environmental impact of nC60, and provides a methodology by which the potential environmental impacts of other nanomaterials can be evaluated.

Elevated levels of arsenic in groundwater have generated great attention worldwide because of its wide occurrences throughout the world and toxicity at low concentration. This work introduces a possible application at household levels to provide arsenic-safe water using nanoscale iron oxide (i.e., magnetite nanoparticles) and iron salts (i.e., ferric nitrate and ferric chloride) as adsorbents and coagulants, respectively. Recent publications illustrate that more than 70 million people are chronically exposed to arsenic-contaminated groundwater and suffer from skin lesions and cancers worldwide. A number of technologies (for example, ion exchange and membrane methods) are currently available to remove arsenic; however, each technique has drawbacks to be applicable in the developing countries. Therefore, it is crucial to develop a technology to treat arsenic-contaminated groundwater. Our results show an immediate reduction of arsenic concentration in solution to meet the maximum contaminant level of arsenic (10 microg L-1) in drinking water. Also, iron concentrations in solution are below the World Health Organization guideline value of 300 microg L-1. Contrary to previous results reported by other researchers, arsenic(III), known as more problematic in natural water, is also removed as effectively as arsenic(V) by using our method. When citrate, one of most common organic ligands in environments, is initially added to arsenic-containing solutions, the formation of iron oxides from iron salts is completely inhibited and resulting arsenic concentration remains the same as the initial arsenic concentration, indicating that arsenic removal does not occur. However, other common carboxylic acids such as tartarate, succinate, malate, formate, and tricarballylate, have a negligible impact on preventing the formation of iron hydroxides and resulting arsenic removal from solution. This work shows the efficient method to reduce high arsenic concentrations in groundwaters and better understanding of arsenic removal mechanisms using iron salts and iron oxides.

Ethanol is playing a key role in current discussions on energy, agriculture, taxes and the environment. This work addresses the potential environmental impacts and behavior of subsurface fuel-ethanol releases. A continuous-flow 8,150-L pilot-aquifer tank packed with sand was used to simulate two spill scenarios: (1) fuel-grade ethanol (E95, 95% v/v ethanol, 5% v/v hydrocarbon mixture as a denaturant) into uncontaminated soil, and (2) neat ethanol (100% v/v) release onto gasoline-contaminated soil. Measurement of ethanol and hydrocarbon concentrations in groundwater and capillary-fringe pore water from over 30-locations over 120+ days provided a quantitative evaluation of the extent of plume migration, longevity, and impacts to groundwater quality. Real-time quantitative PCR (RTQ-PCR) was also used to estimate temporal and spatial trends in concentrations of total bacteria (16s rDNA) and various genotypes that inhabit different electron-accepting zones at sites undergoing natural attenuation. Furthermore, the anaerobic catabolic gene bssA (coding for benzylsuccinate synthase), and the aerobic catabolic genes dmpN (coding for phenol hydroxylase) and todC1 (coding for toluene dioxygenase) were also quantified as biomarkers for BTEX biodegradation. Ethanol, which is buoyant and hygroscopic, quickly migrated upwards and spread laterally within the capillary-zone. Horizontal migration of ethanol occurred through a shallow thin layer with minimal vertical dispersion, and was consistently 10-times slower than the preceding bromide tracer. Dyes, one hydrophobic (Sudan-IV) and one hydrophilic (Fluorescein) provided evidence that the fuel hydrocarbons phase separated from the E95 mixture as ethanol was diluted by pore water and its cosolvent effect was diminished. The neat ethanol spill mobilized the pre-existing hydrocarbon NAPL down-gradient. Neither of the highly concentrated spills had a bactericidal impact on the microbial community, and cell growth coincided with ethanol availability. Bacteria concentrations increased by at least one-order of magnitude as did bacteria harboring todC1 and dmpN after each spill. However, bacteria harboring bssA were not detected, suggesting that longer acclimation time may be required to establish anaerobic hydrocarbon degraders. It appears that microbial impacts are mainly related to O 2 depletion, but rebound can be relatively fast, and fortuitous proliferation of aerobic BTEX degraders (growing on ethanol) is likely following the relatively rapid ethanol washout.

Three anaerobic, dechlorinating consortia were enriched from different origins using methanol and tetrachloroethene (PCE) and maintained for approximately three years. Characterization of the consortia with terminal restriction fragment length polymorphism (TRFLP) and qualitative and quantitative PCR (qPCR) demonstrated that all three dechlorinating communities were dominated by Dehalococcoides and Dehalobacter spp. Monitoring methane production combined with qPCR for archaea demonstrated that complete PCE dechlorination occurred in the presence and absence of methanogenesis. Combining results for denaturing gradient gel electrophoresis (DGGE) and qPCR for reductive dehalogenase genes suggested that one consortium contained a strain 195-type organism with the ability to respire vinyl chloride (VC). The effect of the anionic surfactant SteolRTM CS-330 on PCE dechlorination was evaluated using pure and mixed dechlorinating cultures. Sulfurospirillum multivorans was the only pure culture able to dechlorinate in the presence of SteolRTM CS-330. S. multivorans was present in consortia OW and CH, and these consortia were capable of partial dechlorination to cis-dichloroethene ( cis-DCE) in the presence of SteolRTM CS-330. Monitoring Dehalobacter spp., Sulfurospirillum spp. and Dehalococcoides cell numbers in consortium OW during exposure to SteolRTM CS-330 with qPCR demonstrated that the cell numbers were reduced by 79%, 88% and 99%, respectively. Dechlorination past cis-DCE was never recovered after resuspension into surfactant free media. Two experimental controlled release systems (ECRS) were employed to examine PCE source zone bioremediation and the efficacy of bioaugmentation. Results obtained demonstrated that bioaugmentation enhanced PCE removal by a factor of 1.6 over biostimulation alone, but minimal ethene production was observed in both systems. Interestingly, both systems contained Dehalococcoides capable of growth on VC; but VC dechlorination was not observed. It was also demonstrated that the bioaugmented populations became dominant, and that the dechlorinating organisms were not washed out of either system. Analysis of energy flow demonstrated that the dechlorinating populations consumed more energy than the methanogens until chloroethenes became limiting. A comparison of cell numbers between archaea and dechlorinating organisms showed that cell numbers did not correlate to activity, since methanogens had higher cell numbers throughout the experiment.

Association of hydrophobic organic compounds with dissolved organic matter in natural water systems may impact a contaminant's ability to transport across synthetic membranes. Importantly, these interactions can create interferences when monitoring ambient levels of contaminants with a potential for biouptake. The influence of water-quality matrix conditions on the transport and lipid uptake of five hydrophobic organic compounds of environmental concern was investigated by partnering semipermeable membranes with a model lipid phase in a batch dialysis system. Contaminants fell into two characteristic groups based on the response of transport and lipid uptake to exposure conditions: one for which behavior was largely independent of water-quality matrix conditions and one for which alterations to the bulk aqueous phase were impactful. For short exposure periods, the abiotic technique demonstrated the potential to qualitatively replicate the root-to-shoot translocation behavior of non-ionized hydrophobic organic compounds in plant systems.

Samples of atmospheric particles were analyzed for organic and elemental analysis at three sites in Houston, TX. Samples for the quantification of individual organic compounds were collected during August 2000--September 2000 and analyzed for molecular speciation. A chemical mass balance (CMB) model was applied to the organic speciation data to estimate the contributions of the eight possible sources to the fine particulate matter mass in Houston. Major contributors to PM2.5 included gasoline vehicles, diesel vehicles, meat cooking and wood combustion with smaller contributions from vegetative detritus. It was found that PM2.5 mass was also dominated by other organics and secondary sulfate. Samples for airborne metal analysis were collected and analyzed by two different chemical analysis methods; Inductively Coupled-Plasma Mass Spectrometry (ICP-MS) and X-Ray Fluorescence (XRF). Positive matrix factorization (PMF) was applied to the elemental concentration data for source identification and apportionment. PMF resolved five physically interpretable factors at each site of which four were found to be common at all sites: crustal material, road dust, wood burning, and sea salt. The composition of the remaining factor was similar, but not identical at the three sites and had an elemental composition similar to industrial combustion. Crustal material is the most important contributor at each site.

On-lattice Monte Carlo simulations were performed to investigate the effect of collision efficiencies alpha of particles on the morphology of heterodeposits. The model predicts that the structure and surface chemistry of such deposits are determined by particles with large and small values of alpha, correspondingly. The case of homodeposition onto a rough substrate was also studied. The best "memory" of the deposit measured as a rate of decay of the Fourier amplitude corresponding to the wavelength of the initial roughness, was found to correspond to intermediate values of alpha. Cross-flow membrane filtration experiments using monodisperse latex suspensions were performed for validation of the Sethi's extended model. A slightly more complex structure at the cake-suspension interface was hypothesized to explain differences between model calculations and experiments. A representation of the cake with a gradually changing solids concentration allowed for better matching of the extended model and experimental results for particles diffusively depositing onto membrane.

Alumoxane-derived membranes are characterized and compared with commercial anodized alumina and polycarbonate track-etched membranes. The alumoxane-derived membranes were produced using two different types of ligands, acetic acid and (methoxyethoxy)acetic acid, or mixes of the two to alter the membrane characteristics. Membranes were studied using scanning electron microscopy, atomic force microscopy, nitrogen adsorption-desorption, cleanwater flux experiments, goniometer measurements, and Zeta-meter measurements to determine membrane morphology, pore size distribution and shape, permeability, hydrophobicity, and surface charge. Alumoxane-derived membranes were found to have a nodular morphology with over 90% of pores between 5 and 25 nm and permeability ranging from 0.3 to 1.5 nm$\sp2$. The two ligands used did not produce large differences in the overall characteristics of the membranes. Alumoxane-derived membranes exhibited similar permeabilities to the commercial membranes tested. Carboxylate-alumoxanes show considerable promise as precursors to membranes and other alumina products.