Multiple metal-gill modelling based on the toxic unit concept suggests that metals with the same toxic actions (e.g. Pb and Cd interacting at Ca-gill channels) will exhibit strictly additive binding at the gills of fish if the concentrations of the two metals sum to one toxic unit. Due to the non-linear nature in which metals bind to fish gills, the metal mixture will be more than additive below one toxic unit and less than additive above one toxic unit. This research tested the models by exposing rainbow trout to mixtures of Cd and Pb to investigate the metal-gill binding of these two metals when present in mixtures with fish. The relationship between Cd and Pb in mixtures was also investigated when natural organic matter (NOM) was added to the treatment solutions. Juvenile rainbow trout (5 g) were exposed to equal mixtures of Cd and Pb at 0.75, 1.5, 2.25 and 3.0 µM each. The high gill-Pb accumulation in relation to gill-Cd was unexpected and suggested an additional gill-binding site for Pb aside from the apical Ca channels on the gill. 96 h toxicity experiments revealed that Cd and Pb in mixtures were more toxic than either Cd or Pb alone. The bioaccumulation and partitioning of Cd and Pb within the body of 50 g rainbow trout was investigated when these fish were exposed to mixtures of Cd and Pb. The accumulation of metals within the trout body did not change between the single metal and mixture exposures. To investigate how Pb affects Cd binding to fish gills, and how these metals exert toxicity when present in mixtures, trout (2 g) were exposed to a range of Cd concentrations (0.75, 1.5, 2.25 and 3.0 µM) while maintaining constant Pb concentrations over the same concentration range. Gill binding results revealed that Pb reduced or inhibited gill-Cd binding. With the addition of NOM, this inhibition was lost. LT50 results for fish exposed to metal mixtures for 96 h revealed that without NOM, the mixture toxicity was dependent on Pb concentration. With the addition of NOM, mixture toxicity decreased with increasing Pb.

Natural and synthetic estrogens are some of the most potent hormones detected in the environment. Agriculture fields often release higher concentrations of natural estrogens to the environment, but wastewater treatment plants (WWTPs) commonly release higher concentrations of synthetic estrogens. Estrogens can disrupt endocrine functions in wildlife and humans. Less attention has been paid to the fate and occurrence of estrogens in agricultural operations than WWTPs. Their fate is influenced by major mechanisms such as sorption and biodegradation. Sorption typically accounts for less than 10 percent of estrogen removal in WWTPs. However, biodegradation is a primary method for estrogen loss at high ammonia concentration in the agricultural and municipal operation. Less attention has been paid to the biodegradation kinetics of estrogens in the field application. Therefore, this dissertation focused on the occurrence of estrogens in agricultural fields and their biodegradation by a mixed culture and a pure culture. The estrogens in turkey litter amended fields might be biodegraded to some degree by turkey litter borne bacteria. The estrogen biodegradation by a mixed culture showed different mechanisms for each estrogen. E1 and E2 were easily degraded as a carbon source of the mixed culture. E3 and EE2 were favorable for cometabolic degradation by AOB. EE2 was not readily biodegraded by the mixed culture due to a steric hindrance of enzyme expression and EE2 metabolism in the ethynylgroup of EE2. The cometabolic kinetics of individual estrogen was evaluated by using a pure culture. The cometabolism of estrogen was demonstrated by a reductant model. This model appropriately estimated the cometabolic kinetics of individual estrogens. In addition, the effect of antibiotics on the hormone degradation was investigated in Sequencing Batch Reactors (SBRs). No significant difference was detected for the removal efficiency of target compounds in the SBRs in presence or absence of antibiotics (oxytetracycline and chlortetracycline) during long sludge retention time (SRT). However, the effluent organic matter (EfOM) was less decomposed with the presence of antibiotics, especially causing less degradation of the humic-like substances in EfOM. The results indicated the flux of antibiotics to WWTPs did not affect hormone degradation, but reduced the decomposition of humic-like substance. Finally, the findings from the research provide insight into how biodegradation influences estrogen removal in agricultural fields and municipal WWTPs. The models developed in this research yielded valuable predictive values for engineered systems.

Colloidal macromolecular organic matter (COM), which makes up a large portion of the bulk dissolved organic matter (DOM) in marine environments, has the capability to modify the bioavailability of potentially toxic metals to aquatic organisms. In order to better understand the bioavailability of some of these metals to estuarine bivalves, American Oysters (Crassostrea virginica) were exposed to different types of natural colloidal (COM) and model (alginic acid, carrageenan, and latex particles) organic biopolymers, tagged with gamma-emitting radioactive metal ions (110mAg, 109Cd, 57Co, 51Cr, 59Fe, 203Hg and 65Zn) or 14C (to sugar OH groups). Natural COM was obtained from Galveston Bay water by 0.5µm filtration, followed by cross-flow ultrafiltration, using a 1kDa ultrafilter, diafiltration and freeze-drying. COM and DOM model compounds were used in the bioavailability experiments at 2 ppm concentrations. Separate 16-hour experiments using varying sizes of latex particles assessed the lowest size of colloids that can be filtered from the water. Results showed that filter-feeding bivalves could efficiently remove particles as small as 0.04µm (40nm) in diameter, with removal halftimes of 2.5 to 5.5 hours, equivalent to filtration rates of about 50±15 ml/hour, or about 3 L d-1 g-1, which are typical values for these oysters. Results of the 20-hour bioavailability experiments demonstrated that oysters could effectively filter metals bound to COM, with the metals bound to alginic acid COM being removed at the highest rates from the water. However, the metals bound to alginic acid were not found in oyster meat in the highest amounts: it was the metals associated with the carrageenan COM. The 14C labeled biopolymer data also showed alginic acid to be removed from the water at the highest rate and, contrary to the metals, was also present in the meat in the greatest amounts. Thus, while previous experiments suggested that the quantity (i.e., concentration) of natural organic matter is important for metal bioavailability, it was shown here that the “quality”, i.e., the type of natural organic matter, is also a factor for controlling bioavailability, removal and incorporation rates of metals to oysters.

Some community water systems using sources containing elevated levels of fluoride, in the United States and worldwide, struggle to treat their drinking water to healthy fluoride concentrations. Many treatment plants in the U.S. currently use aluminum based salts, such as aluminum sulfate and polyaluminium chloride, as coagulants during conventional treatment for removal of particles from drinking water sources. Moreover, enhanced aluminum sulfate, or alum, coagulation requires higher concentrations of aluminum added to the process and has been shown to be effective for removal of disinfectant byproduct precursors, i.e., natural organic matter (NOM). The presence of fluoride may interfere with the formation of aluminum hydroxide precipitates, and interrelationships among NOM, aluminum precipitation and fluoride removal are not well understood. A fundamental understanding of how fluoride alters the properties of aluminum precipitates and how fluoride and NOM molecules compete as ligands interacting with soluble aluminum species is lacking. As a result, the development of guidelines for implementation and optimization of a treatment scheme that uses aluminum in the presence of fluoride requires a multi-faceted approach in which the development of a mechanistic understanding of these interactions is conducted in concert with macroscopic experiments to identify optimum conditions for simultaneous removal of fluoride and NOM. To date, little research has looked at the efficiency of removing both fluoride and organics from the perspective of the precipitation process. To provide a foundation for revising treatment techniques, this research evaluated the effect of co-precipitating aluminum in the presence of fluoride, organics, and in multi-ligand systems to characterize the solid precipitate and removal competition. This research verified the formation of a co-precipitate in the presence of fluoride and certain low molecular weight organics. Co-precipitation from organics and fluoride competes for removal, especially at low alum coagulant doses, complicating treatment for resource limited areas. / text

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Surface waters subject to algal blooms have a high rate of fouling water treatment filtration membrane. These waters typically contain high concentrations of hydrophilic organic carbon compounds such as proteins and polysaccharides. These compounds have been found to contribute greatly to membrane fouling. In this study the fouling propensity, and the components of the fouling layer, for microfiltration (MF) and ultrafiltration (UF) membranes, were characterised for samples taken from a wastewater treatment plant with lagoons prone to algal blooms and a blue-green algae culture (Anabaena circinalis). It was found that the organic carbon compounds released during the growth phase (EOM) of Anabaena circinalis have a similar fouling propensity for UF than those released during the lysis phase (AOM), and a slightly higher fouling propensity for MF. However, due to the presence of higher UV-absorbing hydrophilic compounds, higher concentration of intracellular proteins and/or humic acid-like matter in the AOM, irreversible fouling was significantly higher during the lysis phase.

Natural organic matter (NOM) is described as an intricate mixture of organic compounds that occurs universally in ground and surface waters. After treatment for potable use, there is NOM remaining in the water that reacts with the chlorine used for disinfection to form disinfection by-products (DBPs). Some of the DBPs, trihalomethanes (THMs) are regulated. Several water treatment works (WTWs) in the Yorkshire Water and United Utilities (previously North West Water) region in England have recently experienced difficulty in meeting THM limits (100 µg L-1) in their finished drinking water at certain times of the year. An investigation into how NOM changes seasonally, pragmatic methods of NOM analysis and its reactivity with chlorine was undertaken. By separating the NOM using adsorbent resins into fractions, it was possible to gain an insight into the seasonality of NOM. It was observed that a particular, difficult to remove fraction was always more reactive with respect to THM formation in autumn. Some of the methods proposed in the literature were used here with varying successes. It was found that High Performance Size Exclusion Chromatographic methods were most useful to the WTW operators for optimising treatment processes. It is known that the formation of DBPs is very complex. An attempt was made to predict the reactivity of a raw water in terms of THM-FP by looking at the NOM makeup. However, it was found that the fluorescence spectra combined with the fluorescence index of raw water and chlorinated samples gave more insight into the reactivity of the raw water at a particular time than knowing the fraction distribution. The use of fluorescence as a tool for understanding chlorine-NOM reactions is promising.

Seasonal periods of high rainfall have led to difficulties in removing sufficient natural organic matter (NOM) to meet trihalomethane (THM) standards, and hence better or alternative treatments are required. Typically bulk water parameters such as dissolved organic carbon (DOC) and UV absorbance at 254nm (UV254) are used to optimise treatment processes. Here the isolated fraction character and molecular weight (MW) distribution was used in conjunction with bulk water parameters to tailor process options for the treatment of humic rich waters. Three options for the removal of NOM were proposed. A staged coagulation based on the optimisation of isolated fractions. The results showed that although no significant reduction in DOC or UV254 was observed filter breakthrough was significantly reduced. Secondly a novel magnetic ion exchange process (MIEX®) for the removal of NOM was evaluated. The results showed that a combination of MIEX® and ferric reduced the THM formation potential (THMFP) by more than 50% and lower MW compounds that are known to be untreated by conventional coagulation were reduced. This option was also shown to be the most robust option for the treatment of waters with differing quality caused by seasonal changes and different catchments. Finally the addition of a range of adsorbents including carbons, hydroxides and clays to both the raw water and the isolated low MW fractions showed that an increase in DOC and UV254 removal was achievable. This was proposed as a post coagulation option during times of high organic loading. All processes provide viable options for the treatment of humic rich waters during times when current processes are being challenged and having difficulty meeting THM standards.

Le devenir des anciens sites miniers est un sujet de préoccupation sociétale. Afin de garantir la protection de l'écosystème ainsi qu'un impact radiologique minimal sur la biosphère, il est important de comprendre les paramètres qui régissent la migration de l'uranium (et de ses produits de désintégration, en particulier le radium 226) et d'être capable de le modéliser. Dans la nature, parmi les phases qui peuvent retenir 238U(VI) et 226Ra(II), la tourbe est connue pour avoir une forte affinité pour l'uranium VI. La tourbe sèche étant généralement composée à près de 90% de matière organique, l'objectif de cette étude est de qualifier et de quantifier la capacité d'adsorption et de désorption de la matière organique de la tourbe pour 238U(VI) et 226Ra(II). Les échantillons de tourbe prélevés à proximité de l'ancien site d'extraction d'uranium des Sagnes (Limousin, France) ont été caractérisés et ont ensuite été utilisés pour des expériences d'adsorption et de désorption en btach. Les résultats montrent que l'adsorption de 226Ra(II) sur la tourbe est supérieure à 97% pour pH>4-6 (suivant la teneur en particules détritiques dans la tourbe), ce qui correspond à des valeurs de Kd de 4500 pour 500mL/g. Quand à elle, l'adsorption de 238U(VI) est supérieure à 80% à pH>3, avec des valeurs de Kd qui atteignent 11000 mL/g vers pH 4.5. La désorption mesurée après un mois reste très faible. Contrairement aux tourbes classiques, la tourbière des Sagnes présente la particularité d'avoir une charge détritique importante (jusqu'à 50% de la masse de la tourbe sèche). L'interprétation des courbes de rétention de 238U(VI) et 226Ra(II) nécessite au préalable de discriminer à l'aide de modélisations, la contribution des différentes phases minérales présentes (oxyde de fer, phyllosilicates). Un modèle opérationnel, représentant la fraction organique comme un échangeur d'ions, a été proposé. Celui-ci permet de décrire le comportement de ces deux radioéléments sur la fraction organique de la tourbe. / The environmental footprint of former uranium mining sites is a major concern for society. In order to guarantee the protection of ecosystems and thus a minimal radiological impact on the biosphere, it si important to understand and to be able to model the phenomena controlling the migration of uranium and its decay products, specially radium (226Ra) (AREVA's Envir@Mines project). In the environment, among solid phases which can retain 238U(VI) and 226Ra(II), peat is known to have relevant affinity for U(VI). Because peat is usually composed at 90 % dry weight of organic matter, the aim of this study was to qualify and quantify peat organic matter affinity for 238U(VI) and 226Ra(II). Peat samples extracted from Les Sagnes (close to a former uranium mining site in Limousin area, France) was characterized andbatch adsorption/desorption experiments were conducted. The results indicate that 226Ra(II) adsorption onto that peat is higher than 97 % for pH>4-6 (depending on the organic/mineral ratio in dry peat) corresponding to Kd values about 4500 for 500mL/g and 238U(VI) adsorption is higher than 80 % at pH>3 with Kd maximal values reaching 11000 mL/g around pH 4.5 . Only a little desorption was measured after one month.An ion exchange modelling for radium adsorption onto one type of organic matter sorption site was enough to fit the experimental adsorption Kd for the peat over the whole range of Ph . However, uranium sorption on peat can be modelled on that organic sorption site only for pH 5 to 10. From Ph 5 to 10, to explain the experimental uranium adsorption Kd values (close to 1500 mL/g), uranium sorption onto mineral phases (such as smectite and iron oxide in this study) has to be considered. An operational data set is given for both 238U(VI) and 226RA(II) sorption onto Les Sagnes peat. Unlike usual peat, peat from Les Sagnes contains more than 10 % dry weight of mineral matter. That is why it is necessary to modele sorption of those two radioelements onto mineral phases (such as smectite and iron oxide, in this study), to discriminate which part of the sorption is due to mineral phases and which one id from organic matter. An operational dataset for 238U(VI) and 226Ra(II) sorption onto Les Sagnes organic matter was determined.