The influence of surfactants on a perchloroethene dechlorinating mixed culture was investigated in laboratory experiments. Seven surfactants, representing each of the surfactant classes, were screened for their effects on the rate and extent of perchloroethene dechlorination. Based on screening results, a nonionic surfactant, Tween 80, and an anionic surfactant, Steol CS-330, were selected for use in further studies. Dechlorination of perchloroethene to dichloroethene, vinyl chloride, and ethene occurred in all Tween 80 amended microcosms with a depressed rate of ethene production as the only adverse effect. Steol CS-330, however, inhibited dechlorination beyond dichloroethene at all surfactant concentrations exceeding 25 mg/L. Attempts to acclimate a culture to the surfactant were unsuccessful. Inhibition of vinyl chloride and ethene production was reversible upon dilution of the surfactant to 10 mg/L or below indicating that surfactant interactions with the enzyme system responsible for reductive dechlorination of dichloroethene was the most likely cause of inhibition.

A mathematical simulation model is developed that calculates the evolution of particle removal and headloss in a packed bed filter, as functions of the morphology of the colloidal particle deposits in the filter. The expressions derived are based on the postulate that particles form deposits that grow as mass fractals. The model is calibrated and validated with a set of laboratory data previously obtained. The calibrated value of fractal dimension was found to coincide with measurements obtained in an earlier study using light scattering. The effect of the filtration velocity and particle size on the fractal dimension of the deposits is evaluated. The hypothesis that higher filtration velocities create denser deposits is supported. However, a trend of increasing fractal dimension with decreasing particle size runs counter to theoretical expectations. The model is extended to include the effect of variable conditions in the influent.

The influence of dechlorinating microorganisms on PCE and its reduction products in a residual non-aqueous phase liquid (NAPL) source zone was investigated. Experiments were conducted in upflow anaerobic columns containing glass beads contaminated with a residual NAPL consisting of tridecane and PCE. Columns were inoculated with a mixed PCE-dechlorinating culture, and fed a nutrient medium that included electron donor (pyruvate and/or lactate) at a wide range of concentrations. The systems that were monitored for effluent organic acids (pyruvate-fed) demonstrated evidence of active fermentation. Comparisons between biotic and abiotic columns demonstrated that dechlorination resulted in an increase in total PCE removal, up to a factor of 16 over dissolution. PCE was sequentially reduced as far as vinyl chloride. Total chlorinated ethenes removal was enhanced up to 6.5 times over dissolution removal. The system fed the highest electron donor level, interestingly, lost dechlorinating activity early in the experiment.

The settling velocity of aggregates found in engineered water and wastewater treatment facilities are usually assumed to follow Stokes' law. These particles, however, are typically porous and may be fractal in nature. As a result, they have very different sedimentation characteristics. This study focuses on the comparison of several techniques used to characterize the settling properties of fractal aggregates. Aggregates made of latex particles destabilized using calcium nitrate were formed in the laboratory. Settling velocity and size were then determined for each floc using latex particles ranging 0.03 mum, 0.05 mum, and 2.65 mum in diameter. Light scattering techniques were used to calculate the fractal dimension of the aggregates. Fractal dimension ranged from 1.6 to 2.3 in the experiments. A settling column was constructed to analyze actual settling velocities of flocs. Observed settling velocities of these flocs were consistently higher than those predicted using Stokes' law (which assumes an impermeable sphere).

In a previous study, pilot-scale bioslurry reactors were used to treat soils highly contaminated with 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT). The treatment scheme involved a soil washing process followed by two sequential aerobic slurry reactors augmented with DNT mineralizing bacteria. This previous work found that constant monitoring was necessary to avoid long lag periods upon refeeding. In this study, it was determined that the heterogeneous distribution of soil in the reactor deleteriously impacted direct monitoring of DNT concentrations. Instead, the use of nitrite production or NaOH consumption as surrogate monitoring parameters proved to be more accurate predictors of reactor performance. A model was developed to predict the distribution and biodegradation of DNT in the reactors. Analysis of model results showed that the maximum substrate utilization rate controlled DNT degradation rates in the reactor, a population shift occurred after approximately 26 days, and phosphorous was limiting at high solids loading rates.

The bioavailability of sorbed organic chemicals is a major concern in the application of bioremediation processes to contaminated sediments. Sorption of pollutants may lead to the inability of microbes to come in contact with the compound. Studies presented herein investigate the biodegradation and desorption of fluorene, a 3 ringed polynuclear aromatic hydrocarbon (PAH), in estuarine sediment-water slurries. Adsorption of fluorene to sediments with 1.4% organic carbon was characterized with a linear isotherm. Desorption was characterized through step-desorption tests and temporal-desorption tests. Step-desorption studies confirmed that desorption was completely reversible, and batch desorption tests confirmed that desorption rate was rapid. Fluorene biodegradation was confirmed with $\sp{14}$C mass balance experiments, and fluorene disappearance was monitored in both the sediment and aqueous phase. In biologically active systems, fluorene was rapidly degraded to levels below detection limits. These studies conclude that the rate of fluorene disappearance in biologically active systems is controlled by microbial degradation rates and is not limited by desorption.

Column transport experiments were conducted under saturated conditions to examine the effects of cell concentration and media pre-coating. Two strains of E. coli were used in the study; the commonly studied laboratory organism E. coli K12 D21 and a mutant of the waterborne pathogen E. coli O157:H7. Column experiments were conducted with both clean sand and sand that was pre-coated with bacteria. The influent concentration of the E. coli strains was varied over several orders of magnitude to examine the effect of cell concentration. Concentration dependent removal rates were observed for both organisms in both the clean and media pre-coated sand columns. It was also found that the media pre-coating either does not influence the transport behavior or it decreases the attachment efficiency. Although differences in transport are observed, these differences are not large enough to have a significant influence on the predicted travel distances. / Des expériences de transport par colonne ont été menées afin d'examiner les effets de la concentration des cellules et du pré-revêtement de média. Deux souches de bactéries ont été utilisées: E. coli K12 D12 et une souche mutante E. coli O157:H7. Les expériences par colonne ont été menées avec du sable propre et du sable qui a été préalablement enduit de bactéries. La concentration de l'influent en bactérie a été variée sur plusieurs ordres de grandeur pour examiner l'effet de la concentration cellulaire. Une dépendance du taux d'élimination à la concentration a été observée pour les deux souches de bactéries dans les deux types de sable. De plus, le pré-revêtement de média n'influence d'aucune façon le comportement du transport ni en réduit l'efficacité d'adhésion. Bien que des différences dans le transport ont été observées, celles-ci n'ont eu aucun effet significatif sur la prédiction de la distance à parcourir.

The attachment efficiency of two strains of Escherichia coli O157:H7 – one pathogenic strain and another non-pathogenic strain – was measured over a range of solution ionic strengths and in two different granular systems: a simple system made of clean quartz sand and a real system made of natural subsurface soil. In this study, the relevance of the non-pathogenic strain of E. coli O157:H7 as a potential surrogate for its pathogenic counterpart was investigated. The results suggest that it is not straightforward to find an appropriate surrogate for the pathogenic strain. Different porous media begets different attachment efficiency of the potential surrogate strain relative to the attachment efficiency of the toxigenic strain. A modest attempt was also made to build an artificial system that mimics the natural soil, by coating the clean granular sand with humic acids and adding clay component. / Pour étudier la contamination d'eaux souterraines, l'efficacité d'adhésion de deux variétés d'E. coli O157:H7 – une pathogène et une autre non-pathogène – a été mesurée sur une gamme de force ionique dans deux systèmes granulaires : un système simple fait de sable de quartz propre et un système naturel de sol souterrain. Dans cette étude, la pertinence de la variété non-pathogène (E. coli O157:H7) comme substitut potentiel pour sa contrepartie fut étudiée. Les résultats suggèrent qu'il est très difficile de trouver un substitut approprié de la variété pathogène pour ce type d'études, car différents médias porreaux engendrent différentes efficacités d'adhésion de la variété substitut potentielle. Une tentative a aussi été faite de construire un système artificiel dans le labo qui imite le sol naturel, en enrobant le sable de quartz avec des acides humiques et par l'addition d'un composé d'argile.

As global water resources decline, reuse of domestic greywater for the irrigation of home gardens is quickly becoming widespread in many parts of the world. However, the sanitary implications of reusing greywater to water edible crops remain uncertain. This study examined the benefits and risks associated with domestic greywater reuse for the purposes of vegetable garden irrigation. Untreated (settled only) and treated (settling and slow sand filtration) greywater collected from a family home was analyzed for basic water quality parameters, over a period of eight weeks. During that time, both greywaters were used to irrigate individually potted plots of lettuce, carrots and peppers in a greenhouse. Tap water was used as control. Upon maturity, plants were harvested and the edible portions tested for fecal coliforms and fecal streptococci, common indicators for the presence of pathogenic microorganisms. Heavy metals were not detected in the greywater, but both fecal coliforms and fecal streptococci were present in high levels, averaging 4 x 105/100mL and 2 x 103/100mL of greywater, respectively. Despite these high counts, no significant difference in contamination levels was observed between crops irrigated with tap water, untreated and treated greywaters. Fecal coliform levels were highest in carrots and fecal streptococcus levels highest on lettuce leaves. However, contamination levels for all crops were low and do not represent a significant health risk. Plant growth and productivity were unaffected by the water quality, owing to the low N, P and K levels of the greywater. These results reinforce the potential of domestic greywater as an alternative irrigation source / Dans le contexte d'un déclin et d'une perte de fiabilité des ressources hydriques du globe, la réutilisation des eaux grises (eaux le lavage) domestiques pour les fins d'irrigation devient une option populaire pour les ménages un peu partout dans le monde. Pourtant, les implications sanitaires d'une telle pratique pour l'irrigation des plantes comestibles ne sont pas encore bien comprises. Cette étude vise à examiner les bénéfices et risques associés à la réutilisation des eaux grises pour arroser les jardins potagers domestiques. Il met son focus sur la possibilité de contamination des légumes par des organismes pathogéniques et les métaux lourdes qui peuvent être présents dans les refuts domestiques. Les eaux grises d'une famille montréalaise ont été collectionnés et analysés pour des paramètres de base, y inclut les pathogènes et les métaux lourds, sur une période de 8 semaines. Pendant ce temps, ces eaux grises ont été utilisés à irriguer des plantations individuels de laitues, carottes, et poivrons rouges dans une serre de recherche. L'eau du robinet a servi comme contrôle. À la maturité, les plantes ont étés cueillis et les portions comestibles testés pour la présence des coliformes et des streptocoques fécaux, deux bactéries normalement utilisés pour indiquer la présence d'organismes pathogéniques. Puisque les métaux lourds n'étaient pas présents dans les eaux grises, ils n'ont pas étés testés dans les légumes. Les résultats ont indiqué un niveau élevé de bactéries indicateurs dans les eaux grises, mais la différence de contamination entre les légumes irrigués avec les eaux de robinet et ceux irrigués ave

The potential development of antibacterial resistance and endocrine disruption has led to increased research investigating the removal of antibiotics like sulfamethoxazole (SMX) and estrogens like 17alpha-ethinylestradiol (EE2) during biological wastewater treatment (activated sludge). Lab-scale studies have been carried out by researchers using activated sludge samples and bacterial isolates to investigate the biodegradability of these pharmaceutical compounds with varying and sometimes contradictory results. Both SMX and EE2 can react quickly with ozone (O₃) thus the implementation of O₃ as a final disinfection step during wastewater (WW) treatment may also result in the removal and transformation of these pharmaceutical compounds. However, the identification and characteristics of the ozonation by-products formed as a result of this treatment has yet to be fully explored. Ozone has also been predicted to increase WW biodegradability, suggesting its potential as a pre-treatment to activated sludge. The work presented in this thesis proposes an innovative way to evaluate changes in biodegradability and investigate the potential impact of transformation products. The use of controlled mixtures of pure bacterial cultures to model the biodegradation of SMX and EE2 at lab-scale was studied. This approach ensures a consistent microbial population that can be precisely repeated throughout a set of experiments, allowing the direct comparison of results, which is not possible using activated sludge samples due to their variable composition. The results showed that specific individual bacteria (R. equi and R. rhodocrous) were capable of successfully degrading SMX and EE2, however when they were combined with other bacteria to form mixtures there were no additive or synergistic effects observed. Using the controlled bacterial mixtures to model the biodegradation of SMX and EE2 separately, we were able to investigate the effects of the addition of an excess carbon source as well as ozone pre-treatment on the biodegradability of these compounds. The results demonstrated that there were no overall trends of co-metabolism of either compound with the excess carbon source and that slight differences in the bacterial composition of the mixture used (±1 to 2 bacterial strains) can alter the degradation trends observed (i.e. rate of compound removal). In general, ozonation increased the biodegradation of SMX by the bacterial mixtures; however the removal of EE2 was decreased. This was explained by the formation of an ozonation by-product that was preferentially biodegraded over EE2. We also investigated the ozone by-products formed after the complete disappearance of EE2. Two of these by-products were identified as open phenolic ring structures, suggesting a decrease in estrogenic activity. Using the YES assay these by-products were determined to be significantly less estrogenic than EE2, however they were observed to be more toxic to male fetal rats (15.5. days post-conception) demonstrating a greater negative impact on testosterone secretion. This emphasizes that a better understanding of emerging treatments such as ozonation is necessary before applying them in water treatment since the by-products may exhibit a greater toxic effect than the untreated parent compound. / Les risques associés au développement de bactéries résistantes aux antibiotiques et aux effets des perturbateurs endocriniens suscitent un intérêt grandissant envers l'étude de l'élimination des antibiotiques, tel que le sulfaméthoxazole (SMX), et les œstrogènes, tel que le 17alpha-éthinylestradiol (EE2), lors de traitement biologique des eaux usées (boues activées). Des chercheurs ayant utilisés des échantillons de boues activées et des isolats bactériens pour évaluer en laboratoire la biodégradabilité de ces composés pharmaceutiques ont obtenus des résultats variables, voire même contradictoires. Considérant que le SMX et le EE2 réagissent rapidement avec l'ozone (O₃), l'utilisation de l'O₃ comme étape de désinfection des eaux usées de traitement peut également entrainer l'élimination ou la transformation de ces composés pharmaceutiques. Toutefois, l'identification et la caractérisation des sous-produits d'ozonation reste à faire. L'ozone a également le potentiel d'augmenter la biodégradabilité des eaux usées, ce qui suggère son potentiel en tant que pré-traitement aux systèmes à boues activées. Le travail présenté dans cette thèse étudie l'impact potentiel des produits de transformation et propose une approche innovatrice permettant d'évaluer les changements de biodégradabilité du SMX et du EE2 basée sur l'utilisation de mélanges contrôlés de cultures bactériennes pures. Cette approche permet l'utilisation d'une population microbienne qui peut être précisément répétée tout au long d'un ensemble d'expériences, ce qui permet la comparaison directe des résultats. Cette reproductibilité n'est pas possible en utilisant des échantillons de boues activées en raison de leur composition microbiologique variable. Les résultats démontrent que certaines bactéries (R. equi et R. rhodocrous), utilisées individuellement, étaient capables de dégrader le SMX et le EE2. Parcontre, lorsque combinées avec d'autres bactéries, aucun effet additif ou synergique fut observé. En utilisant les cultures mixtes pour évaluer les changements de biodégradabilité du SMX et EE2, étudié séparément, nous avons pu étudier les effets de l'ajout d'une source de carbone en excès ainsi que l'effet d'une pré-ozonation. Les résultats n'ont démontré aucune tendance générale liée au co-métabolisme et indiquent que de légères différences dans la composition bactérienne (± 1 à 2 souches bactériennes) peuvent influencer la dégradation (comme le taux d'élimination des composés). En général, la pré-ozonation a augmenté la biodégradation du SMX mais a diminué celle du EE2. Cette diminution est expliquée par la formation d'un produit de transformation préférentiellement dégradé par les bactéries. Nous avons également étudié la nature et l'impact des produits d'ozonation du EE2. Deux de ces sous-produits ne possédent pas d'anneau phénolique, ce qui suggère une diminution de l'activité estrogénique. En utilisant le test YES ces sous-produits ont démontré une estrogénicité plus faible que celle du EE2. Toutefois, ceux-ci ont démontré une plus haute toxicité sur les testicules de fétus de rats (15.5 jours post-conception) mesurée par une diminution de la sécrétion de testostérone. Ces résultats soulignent l'importance de mieux comprendre le devenir des produits pharmaceutiques au cours de traitement des eaux puisque les produits de transformation peuvent présenter un plus grand effet toxique que les composés parents non traités.