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Microbial flocculation is important in wastewater treatment process for an efficient separation of the solid and liquid phases and the removal of organics. Bacterial adhesins may contribute to the formation of microbial flocs since they have been previously found to play a significant role in the formation of biofilms. The overall objective of this work was to analyze bacterial protein adhesins present in the extracellular polymeric substances (EPS), mainly those associated with pili, fimbriae, flagella, and curli, and to determine their role in microbial floc structure and function. Identification of these EPS adhesins may explain their role in biofouling and enhance our understanding regarding the manipulation of bioflocculation. With the exception of flagellin protein FliC, which was distributed towards the outer region of the floc, all the adhesins appeared to be concentrated within the core region of the floc. Antibody staining coupled with confocal microscopy indicated that adhesin proteins associated with flagella (FliC), pili (PilA), fimbriae (FimH), and curli (CsgA, CsgB) represent a significant fraction (10-27%) within microbial flocs. Western blot analyses demonstrated that with the exception of FliC, all the studied adhesins were detected in the EPS matrix. Furthermore, mass spectrometry indicated the presence of pili in the EPS matrix. Under Phosphorus (P)-limited conditions, with the exception of fliC, all the studied genes (fimH, pilO, psiF) exhibited a change in response to P reduction, with fimH gene at the highest expression and an earliest response (1 d). During the nutritional downshift analyses, fimH and pilO genes were expressed within the first six hours of the reaction at significantly greater levels than during P-limited conditions. Taken together, these studies suggest that adhesins associated with pili, fimbriae, and curli play an important role in initial floc formation, and that adhesins associated with flagella either recruit planktonic bacteria to a growing floc or are involved in the interfacial relationships at the floc surface. This information may assist researchers and engineers in broadening the understanding of bioflocculation in conventional biologically based wastewater treatment systems and in advanced technologies, such as hybrid and membrane bioreactors. In addition, this knowledge will be useful in creating molecular tools to aid in the design and monitoring of bioflocculation.

Microbial flocculation is important in wastewater treatment process for an efficient separation of the solid and liquid phases and the removal of organics. Bacterial adhesins may contribute to the formation of microbial flocs since they have been previously found to play a significant role in the formation of biofilms. The overall objective of this work was to analyze bacterial protein adhesins present in the extracellular polymeric substances (EPS), mainly those associated with pili, fimbriae, flagella, and curli, and to determine their role in microbial floc structure and function. Identification of these EPS adhesins may explain their role in biofouling and enhance our understanding regarding the manipulation of bioflocculation. With the exception of flagellin protein FliC, which was distributed towards the outer region of the floc, all the adhesins appeared to be concentrated within the core region of the floc. Antibody staining coupled with confocal microscopy indicated that adhesin proteins associated with flagella (FliC), pili (PilA), fimbriae (FimH), and curli (CsgA, CsgB) represent a significant fraction (10-27%) within microbial flocs. Western blot analyses demonstrated that with the exception of FliC, all the studied adhesins were detected in the EPS matrix. Furthermore, mass spectrometry indicated the presence of pili in the EPS matrix. Under Phosphorus (P)-limited conditions, with the exception of fliC, all the studied genes (fimH, pilO, psiF) exhibited a change in response to P reduction, with fimH gene at the highest expression and an earliest response (1 d). During the nutritional downshift analyses, fimH and pilO genes were expressed within the first six hours of the reaction at significantly greater levels than during P-limited conditions. Taken together, these studies suggest that adhesins associated with pili, fimbriae, and curli play an important role in initial floc formation, and that adhesins associated with flagella either recruit planktonic bacteria to a growing floc or are involved in the interfacial relationships at the floc surface. This information may assist researchers and engineers in broadening the understanding of bioflocculation in conventional biologically based wastewater treatment systems and in advanced technologies, such as hybrid and membrane bioreactors. In addition, this knowledge will be useful in creating molecular tools to aid in the design and monitoring of bioflocculation.

Wastewater microbial flocs can protect microorganisms from inactivation by UV light. This effect is detected as tailing at high UV doses in the UV dose response curve. A double-layer structure composed of an inner compact core surrounded by a loose outer layer was proposed by earlier studies to describe UV resistance of microbial flocs. Due to limited oxygen diffusion into the compact cores, the UV inactivation of compact cores and microbial flocs under anaerobic conditions needed to be addressed. The UV disinfection kinetics under anaerobic culturing condition was nearly identical to that of the aerobic study. Moreover, the role of iron concentration on the differences in the UV inactivation kinetics of flocs and cores was assessed. The increase in UV absorbance of floc material due to iron addition could dominate the UV disinfection kinetics of flocs and cores such that they exhibited similar UV disinfection kinetics.

Wastewater microbial flocs can protect microorganisms from inactivation by UV light. This effect is detected as tailing at high UV doses in the UV dose response curve. A double-layer structure composed of an inner compact core surrounded by a loose outer layer was proposed by earlier studies to describe UV resistance of microbial flocs. Due to limited oxygen diffusion into the compact cores, the UV inactivation of compact cores and microbial flocs under anaerobic conditions needed to be addressed. The UV disinfection kinetics under anaerobic culturing condition was nearly identical to that of the aerobic study. Moreover, the role of iron concentration on the differences in the UV inactivation kinetics of flocs and cores was assessed. The increase in UV absorbance of floc material due to iron addition could dominate the UV disinfection kinetics of flocs and cores such that they exhibited similar UV disinfection kinetics.

Existen diversos problemas relacionados a los sedimentos cohesivos en calidad de aguas, transporte de finos y variados problemas ambientales. Dentro de los motivos de estos problemas se puede nombrar su gran superficie de contacto por unidad de masa, su alta capacidad de sorcion y su capacidad de agregarse y desagregarse al realizar el proceso de floculación. Los procesos de floculación dependen de las propiedades fisicoquímicas del sedimento y del agua, como también de varios mecanismos físicos de los cuales la turbulencia es uno de los más importantes. En el presente trabajo de título se tiene como objetivo estudiar experimentalmente, en una columna de agua, la interacción entre la turbulencia y sedimentos cohesivos en suspensión, para esto se diseñó, construyó y puso en marcha una columna de agua dentro de la cual se encuentran unos agitadores laterales, los cuales cumplen la función de generar la turbulencia y así suspender el sedimento. La manera de analizar los flóculos en suspensión fue filmándolos dentro del estanque, y por el contraste que se genera al colocar un foco de luz en contra de la cámara, se logró determinar las áreas y diámetros promedios de los flóculos en el tiempo al analizar los cuadros de cada video. Mediante un ADV se determinó las características del flujo las cuales se relacionaron con las características de los flóculos. Se utilizó bentonita como sedimento cohesivo, y se realizaron 9 diferentes experiencias, siendo éstas la combinación de 3 estados turbulentos y 3 concentraciones El comportamiento general de cada experiencia fue que las partículas en suspensión fueron desagregándose en el tiempo con un comportamiento relativamente exponencial. Al analizar los resultados, se propuso y utilizó dos diferentes relaciones de floculación, tomando en cuenta las concentraciones y energías cinéticas turbulentas promedios. Con esto se determinaron parámetros para la modelación de los procesos de agregación y desagregación de floculos en un campo turbulento.

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution. / February 2006

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution.

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution.

Overfishing of natural fisheries is a global issue that is becoming more urgent as the human population increases exponentially. According to the Food and Agriculture Organization of the United Nations, over 70% of the world's seafood species are fully exploited or depleted. This high demand for seafood protein is not going away; and, in fact, an astonishing one out of five people in this world depend on this source of protein. Traditional aquaculture practices use pond and flow-through systems which are often responsible for discharging pollutants into the environment. Furthermore, aquacultural feeds often contain high levels of fish protein, so the demand on wild fisheries is not completely eased. Even though traditional aquaculture has these drawbacks, there is a significant movement towards more sustainable practices. For example, implementing recirculating aquaculture systems (RAS) maximizes the reuse of culture water which decreases water demand and minimizes the levels of pollutants being discharged to the environment. And, alternative proteins (e.g., soy bean) are replacing the fish and seafood proteins in aquaculture diets. Accordingly, the research described in this dissertation focused on maximizing the reuse of freshwater fish effluent to culture marine shrimp. More specifically, by using suspended-growth biological reactors to treat a tilapia effluent waste stream and to generate microbial flocs that could be used to support shrimp culture. This RAS technology will decrease water consumption by increasing the amount of recycled water and will also improve effluent water quality. The biomass generated in the bioreactors could be used to feed shrimp with an alternative source of protein. Treating fish effluent to be reused to culture shrimp while producing this alternative feed, could significantly decrease operational costs and make these operations more sustainable. Understanding which ions are critical for the survival and normal growth of marine shrimp in freshwater effluents is essential. It is also very important to understand how to convert an effluent's organic matter into food for shrimp. Results from studies revealed that the marine shrimp, Litopenaeus vannamei, can be raised in freshwater effluent when supplemented with specific ions and wet microbial flocs fed directly to shrimp can enhance growth in shrimp fed a restricted ration of commercial feed. The treatability of the tilapia effluent using suspended-growth, biological reactors and nutritional analysis of the generated biomass were also reported. Carbon supplementation enhanced reactor performance and microbial floc generation. These microbial flocs also proved to be a superior feed ingredient when dried and incorporated into a pellet feed. / Ph. D.