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Recently, treatment plants have adopted biofiltration to compliment conventional treatment and ozonation. Previous literature has focused on passive applications of biofiltration. In this study, several pilot-scale biofiltration trains were designed in parallel to conventional treatment to investigate the impact of nutrient addition (nitrogen and phosphorus), use of hydrogen peroxide, aluminum sulphate (alum), and different filtration media (anthracite vs. granular activated carbon (GAC)) on biofiltration performance. Parameters measured included organic removal, reduction of DBP precursor, improvements in filter runtimes and ultrafiltration (UF) fouling control. Nutrient addition did not improve biofiltration performance. Supplementing hydrogen peroxide (<1 mg/L) decreased headloss, DBP formation potentials while adversely affecting UF fouling. In-line alum addition (<0.5 mg/L) improved biofilter’s ability to control fouling and DBP precursor without adversely impacting headloss. GAC provided superior performance when compared to anthracite. Conventional treatment provided higher DOC, and DBP precursor removal, as well as better UF fouling control compared to biofiltration.

La thèse est consacrée à l'étude des faisceaux encadrés sur des variétés non-singulières projectives et des propriétés géométriques de leurs espaces de modules. En particulier, on donne une généralisation au cas encadré des résultats connus pour les faisceaux (semi)stables sans torsion non-encadrés, comme l'existence de la filtration de Harder-Narasimhan (relative), théorèmes de restriction de Mehta-Ramanathan, compactification de Donaldson-Uhlenbeck, la définition de la classe d'Atiyah relative et la description de l'application de Kodaira-Spencer via la classe d'Atiyah relative, l'existence d'une structure symplectique holomorphe, dans certains cas, sur les espaces de modules de faisceaux encadrés. / The thesis is concerned with the study of framed sheaves on nonsingular projective varieties and the geometrical properties of their moduli spaces. In particular, it deals with a generalization to the framed case of known results for (semi)stable torsion free nonframed sheaves, such as the existence of the (relative) Harder-Narasimhan filtration, Mehta-Ramanathan restriction theorems, Uhlenbeck-Donaldson compactification, the definition of the relative Atiyah class and the description of the Kodaira-Spencer map in terms of the relative Atiyah class, the existence of a symplectic structure, in certain cases, on the moduli spaces of framed sheaves.

A testing apparatus was developed for the determination of the change in permeability of coarse porous media subjected to a decrease in porosity . literature survey was conducted to establish the design criteria for the flow and loading tests. The mthemaUcal model describing flow through course porous media was further developed on a theoretical basis by postulating the layered medium model. Ihis model is a means by which the variability of the particle sizes in the medium is taken into account. The design, construction and operation of the testing apparatus is des:rvx-d. The specimen tested was laded up uo 3,45 MPa; consequently ' the Fbrcheimer aquation in the form of K , Ci/R + Cg was found to yield repeatable values for tiic turbulent friction factor C2, thus providing a means of predicting the change in permeability if the change in porosity and effective particle diameter are known.

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This study focuses on the optimisation of submerged hollow fibre membrane performance by analysing the role of air sparging on the reduction of membrane fouling. In submerged hollow fibre membranes, rising bubbles have been shown to induce shear, liquid movement and fibre displacement. The interaction between fibre movement induced by bubbling and the microfiltration performance was assessed for various parameters (fibre tightness, fibre length, fibre diameter, air flowrate, nozzle size, and feed concentration). A model feed of yeast suspension and a series of isolated fibres were used. The fibre movement was assessed by monitoring the displacement using video recording. Bubble population parameters were also measured. The results suggest that bubbleinduced fibre movement plays an important role in controlling membrane fouling. Investigations of the critical flux at various operating conditions also supported these conclusions. Since energy consumption for aeration is a major contributor to the cost in submerged membranes, the potential to minimise the aeration cost has been tested by implementing intermittent aeration and different nozzle sizes. It was found that an optimum condition associated with a low fouling rate could be reached by combining various aeration intermittencies and nozzle sizes. An attempt to suppress fouling without aeration was made by incorporating vibrations into a submerged hollow fibre membrane system. The effects of vibration frequency, type of yeast (washed and unwashed) on the filtration performance were observed. The impact of coagulant addition on filtration enhancement was also analysed. The performance of microfiltration was evaluated based on its critical flux value. The findings in this preliminary study indicated potential fouling control by applying vibrations to submerged membranes. A semi-empirical model was developed to predict the filtration behaviour by taking into account the bubble-induced shear and fibre movement. The predicted critical flux values suggested that membrane fouling appears to be more prominent at low air flowrate, with tight fibres, and higher feed concentrations. The model fits the experimental data with discrepancies from approximately 0.3% to 20%. The predicted filtration profiles at different operating modes demonstrate the importance of bubble-induced shear and fibre movement in the improvement of filtration performance.