Disinfection byproducts (DBPs), such as organic chloramines, THMs, HAAs, and nitrosamines, are formed during mandatory disinfection processes in drinking water treatment. Many of these DBPs have been shown to be potentially carcinogenic. Extensive research has been conducted on the occurrence and formation of these DBPs. However, there has been limited research on their relationships with each other, which may be important for the understanding of their formation mechanisms, and the nature of their precursors is still relatively unknown. Ultimately, this information will be key for the development of possible improvements in treatment technologies. Results of this study improve the understanding of DBP formation in swimming pool water. Some BFAs and PCP additives were identified as potential DBP precursors. Influence of BFAs and PCP additives on DBP formation in swimming pool water was also illustrated. Results provided feasible strategies to minimize DBP formation while maintaining the efficiency of disinfection.

Disinfection byproducts (DBPs), such as organic chloramines, THMs, HAAs, and nitrosamines, are formed during mandatory disinfection processes in drinking water treatment. Many of these DBPs have been shown to be potentially carcinogenic. Extensive research has been conducted on the occurrence and formation of these DBPs. However, there has been limited research on their relationships with each other, which may be important for the understanding of their formation mechanisms, and the nature of their precursors is still relatively unknown. Ultimately, this information will be key for the development of possible improvements in treatment technologies. Results of this study improve the understanding of DBP formation in swimming pool water. Some BFAs and PCP additives were identified as potential DBP precursors. Influence of BFAs and PCP additives on DBP formation in swimming pool water was also illustrated. Results provided feasible strategies to minimize DBP formation while maintaining the efficiency of disinfection.

Over the past century chlorine has been a reliable disinfectant to reduce transmission of waterborne diseases in drinking water. Concerns about chlorination have increased since it was discovered in the 1970s that use of chlorine in drinking water produces trihalomethanes (THMs), when chlorine reacts with natural organic matter (NOM), which has been observed in increased levels in surface water during the past decades. THM and other disinfection by-products (DBPs) such as some of the haloacetic acids (HAAs) and some nitrosamines are considered probable human carcinogens by USEPA. Since DBPs are still formed even when using alternative disinfectants such as chloramines, treatment processes by which disinfection by-product precursors are removed continue to be studied. Many researchers have demonstrated that the use of pre-ozonation/biological processes in the production of drinking water has the potential to decrease levels of disinfection by-products in finished water more than conventional treatment alone. Two of the parameters which affect the efficiency of DBP precursor removal in biofilters are filter media and filter flow rate. In this research, the biofiltration process was examined using pilot-scale filters receiving ozonated water to determine the relative effectiveness of these parameters for influencing the removal of natural organic matter. The research presented in this thesis initially focuses on determining the effects of flow rate and filter media including GAC (granular activated carbon) and anthracite on decreasing the levels of THM, HAA and nitrosamine precursors in biologically active filters. In the second part, the performances of full-scale and pilot-scale filters at the Mannheim Water Treatment Plant were compared. THM and HAA precursor removal was found to decrease when loading rates were increased, likely due to associated shorter contact times in the filters. Also, higher THM and HAA precursor removal was always observed in the GAC filters than in the anthracite filters. However, removal of nitrosamines was not affected by flow rate or the type of filter media. In general, the pilot-scale filter performance was representative of full-scale filter performance, especially in regards to THM precursor and chlorine demand removal. Statistical evaluation and interpretation of the data for HAA and NDMA precursor removal was more difficult, likely due to the low concentrations of these DBPs which was near their method detection limits (MDLs) and also because of some operational problems with pilot filter #1. Despite these limitations, the results of this study add to the literature concerning the use of different types of media to support biofiltration and reduce DBP precursor concentrations during drinking water treatment.

Over the past century chlorine has been a reliable disinfectant to reduce transmission of waterborne diseases in drinking water. Concerns about chlorination have increased since it was discovered in the 1970s that use of chlorine in drinking water produces trihalomethanes (THMs), when chlorine reacts with natural organic matter (NOM), which has been observed in increased levels in surface water during the past decades. THM and other disinfection by-products (DBPs) such as some of the haloacetic acids (HAAs) and some nitrosamines are considered probable human carcinogens by USEPA. Since DBPs are still formed even when using alternative disinfectants such as chloramines, treatment processes by which disinfection by-product precursors are removed continue to be studied. Many researchers have demonstrated that the use of pre-ozonation/biological processes in the production of drinking water has the potential to decrease levels of disinfection by-products in finished water more than conventional treatment alone. Two of the parameters which affect the efficiency of DBP precursor removal in biofilters are filter media and filter flow rate. In this research, the biofiltration process was examined using pilot-scale filters receiving ozonated water to determine the relative effectiveness of these parameters for influencing the removal of natural organic matter. The research presented in this thesis initially focuses on determining the effects of flow rate and filter media including GAC (granular activated carbon) and anthracite on decreasing the levels of THM, HAA and nitrosamine precursors in biologically active filters. In the second part, the performances of full-scale and pilot-scale filters at the Mannheim Water Treatment Plant were compared. THM and HAA precursor removal was found to decrease when loading rates were increased, likely due to associated shorter contact times in the filters. Also, higher THM and HAA precursor removal was always observed in the GAC filters than in the anthracite filters. However, removal of nitrosamines was not affected by flow rate or the type of filter media. In general, the pilot-scale filter performance was representative of full-scale filter performance, especially in regards to THM precursor and chlorine demand removal. Statistical evaluation and interpretation of the data for HAA and NDMA precursor removal was more difficult, likely due to the low concentrations of these DBPs which was near their method detection limits (MDLs) and also because of some operational problems with pilot filter #1. Despite these limitations, the results of this study add to the literature concerning the use of different types of media to support biofiltration and reduce DBP precursor concentrations during drinking water treatment.

The plasma vitamin D binding protein (DBP) is an a-glycoprotein, synthesised and secreted by the liver, which binds specifically vitamin D and its metabolites. The DBP molecule, has a single high affinity binding site for its ligands, and is present in blood in concentrations about 1000-fold greater than the sum of all its vitamin D ligands. Previous studies have not found any change in the concentration of DBP related to various derangements in mineral homeostasis. Therefore the general view is that DBP has a passive role in the physiology of vitamin D and its metabolites, and simply acts to solubilise and transport these hydrophobic ligands in the aqueous extracellular fluid. However, differences which have been described in its affinity for various vitamin D metabolites suggest that there have been evolutionary influences on the properties of this protein. Furthermore, plasma DBP concentration has been found to change in response to a number of physiological factors, such as changing sex steroid hormone secretion. The aim of the studies presented in this thesis was to investigate variation in the plasma concentration of the DBP in a range of vertebrate species, and in response to a variety of physiological factors. The results suggest that DBP may have an active role in regulating the bioavailability, and hence the utilisation and metabolism of its ligands. DBP concentration has traditionally been measured using immunological techniques. These techniques, although fast and simple, have a number of draw-backs which can be overcome by the use of assays which rely upon functional aspects of the DBP. A saturation binding assay was modified from those described previously. Using this technique, it was found that both the circulating concentration of the DBP and its affinity for 25-hydroxyvitamin D3 (25(OH)D3) varied significantly among a wide range of species of reptiles and birds. This variation did not reflect phylogenetic relationships among the study species, suggesting that the variation was more likely to be the result of selective pressure in response to individual ecological or physiological circumstance, rather than to random mutation. In support of this, both the plasma concentration of DBP, and its affinity for 25(OH)D3 were significantly associated with a number of ecological factors which might be considered to have some significance to vitamin D and calcium homeostasis. In addition, comparative binding data suggests that the ability of the DBP to bind 25-hydroxyvitamin D2 with equal affinity to 25(OH)D3 is an evolutionary innovation of mammalian vertebrates. In order to extend the idea of genetic variation in the concentration and affinity of plasma DBP, two strains of broiler (meat-type) chickens were studied. It was found that both the concentration and the affinity of plasma DBP for 25(OH)D3 was characteristic for each strain, emphasising the sensitivity of DBP to genetic variation. A number of factors have been found to modulate the genetically determined plasma concentration of DBP. Deficiencies of dietary protein and dietary energy, and variation in concentrations of sex steroids were found to affect the circulating concentration of DBP. However, species differences were still apparent, suggesting that the sensitivity of DBP to these physiological modifiers may have developed independently in different species, and may be secondary to genetic determinants of DBP properties. The plasma DBP concentration and specific binding affinity both determine the availability of its ligands for cellular uptake. It is likely that this process is complex, and involves a combination of protein mediated and non-mediated uptake events. This makes DBP a potentially important determinant of the biological actions of its ligands. The studies in this thesis have produced two main lines of argument supporting an active role for DBP in the regulation of vitamin D metabolism and utilisation. The first is that genetic variation in the properties of plasma DBP appears to be genetically determined, and is selected for, both at the between-species, and the within-species level, than it is to random mutation. Secondly, the ability of physiological and environmental factors to modify the circulating concentration of DBP suggests that this protein is responsive to homeostatic processes. It is proposed that DBP is an active regulator of the physiological economy of vitamin D and its metabolites by being itself regulated by a number of genetic and non-genetic factors.

The David L. Tippin Water Treatment Facility (DLTWTF) serving the city of Tampa, Florida is an advanced drinking water treatment facility consisting of coagulation/flocculation, ozonation, granular activated carbon biofiltration, and disinfection by chloramine. New regulations and the recent economic crisis pushed the facility to investigate methods to decrease costs and meet regulatory requirements easier. The two major issues identified as priorities for investigation were the optimization of the biofiltration system and the use of a novel process to reduce the formation of bromate during ozonation. Optimization of the biofiltration system is needed to remove more of the assorted particles that cause biofilms, nitrification in the distribution system, and high chloramine demand. Previous work improved the removal of particles that cause biofilms and nitrification, but was not able address the removal of particles that cause high chloramine demand to a satisfactory degree. Possible factors affecting this high chloramine decay were identified and evaluated at the pilot scale, including filter depth, chloramination of filter backwash water, media material, and nutrient addition. Non-chlorinated backwash water reduced chloramine demand by approximately 30% for GAC filters, and by approximately 50% for anthracite. Generally, anthracite performed slightly worse than GAC. Nutrient addition showed no effect. Filter depth improved chloramine decay, but not significantly enough to warrant the increased material required Bromate control is necessary to prevent the formation of bromate, a regulated carcinogen. Traditional bromate control methods use pH depression. While effective, at the DLTWTF, this forces the increased use of more expensive caustic soda over lime for raising the pH of process water. A novel process known as the chlorine-ammonia process was investigated at the bench scale to identify the ideal ratio of chlorine and ammonia to decrease the formation of bromate to ensure regulatory compliance and allow greater use of lime to decrease costs. The best ratio in this study is 0.45 mg/L NH3 to 0.75 mg/L Cl2 which produced 1.09 ppb bromate at a CT of 6.8 min*mg/L, representing a 84% improvement over the control.

The plasma vitamin D binding protein (DBP) is an a-glycoprotein, synthesised and secreted by the liver, which binds specifically vitamin D and its metabolites. The DBP molecule, has a single high affinity binding site for its ligands, and is present in blood in concentrations about 1000-fold greater than the sum of all its vitamin D ligands. Previous studies have not found any change in the concentration of DBP related to various derangements in mineral homeostasis. Therefore the general view is that DBP has a passive role in the physiology of vitamin D and its metabolites, and simply acts to solubilise and transport these hydrophobic ligands in the aqueous extracellular fluid. However, differences which have been described in its affinity for various vitamin D metabolites suggest that there have been evolutionary influences on the properties of this protein. Furthermore, plasma DBP concentration has been found to change in response to a number of physiological factors, such as changing sex steroid hormone secretion. The aim of the studies presented in this thesis was to investigate variation in the plasma concentration of the DBP in a range of vertebrate species, and in response to a variety of physiological factors. The results suggest that DBP may have an active role in regulating the bioavailability, and hence the utilisation and metabolism of its ligands. DBP concentration has traditionally been measured using immunological techniques. These techniques, although fast and simple, have a number of draw-backs which can be overcome by the use of assays which rely upon functional aspects of the DBP. A saturation binding assay was modified from those described previously. Using this technique, it was found that both the circulating concentration of the DBP and its affinity for 25-hydroxyvitamin D3 (25(OH)D3) varied significantly among a wide range of species of reptiles and birds. This variation did not reflect phylogenetic relationships among the study species, suggesting that the variation was more likely to be the result of selective pressure in response to individual ecological or physiological circumstance, rather than to random mutation. In support of this, both the plasma concentration of DBP, and its affinity for 25(OH)D3 were significantly associated with a number of ecological factors which might be considered to have some significance to vitamin D and calcium homeostasis. In addition, comparative binding data suggests that the ability of the DBP to bind 25-hydroxyvitamin D2 with equal affinity to 25(OH)D3 is an evolutionary innovation of mammalian vertebrates. In order to extend the idea of genetic variation in the concentration and affinity of plasma DBP, two strains of broiler (meat-type) chickens were studied. It was found that both the concentration and the affinity of plasma DBP for 25(OH)D3 was characteristic for each strain, emphasising the sensitivity of DBP to genetic variation. A number of factors have been found to modulate the genetically determined plasma concentration of DBP. Deficiencies of dietary protein and dietary energy, and variation in concentrations of sex steroids were found to affect the circulating concentration of DBP. However, species differences were still apparent, suggesting that the sensitivity of DBP to these physiological modifiers may have developed independently in different species, and may be secondary to genetic determinants of DBP properties. The plasma DBP concentration and specific binding affinity both determine the availability of its ligands for cellular uptake. It is likely that this process is complex, and involves a combination of protein mediated and non-mediated uptake events. This makes DBP a potentially important determinant of the biological actions of its ligands. The studies in this thesis have produced two main lines of argument supporting an active role for DBP in the regulation of vitamin D metabolism and utilisation. The first is that genetic variation in the properties of plasma DBP appears to be genetically determined, and is selected for, both at the between-species, and the within-species level, than it is to random mutation. Secondly, the ability of physiological and environmental factors to modify the circulating concentration of DBP suggests that this protein is responsive to homeostatic processes. It is proposed that DBP is an active regulator of the physiological economy of vitamin D and its metabolites by being itself regulated by a number of genetic and non-genetic factors.

No description available.

No description available.

Abstract Multifunctional enzyme type 2 (MFE-2) catalyses the second and the third reactions in the eukaryotic peroxisomal β-oxidation cycle, which degrades fatty acids by removing a two-carbon unit per each cycle. In addition to the 2-enoyl-CoA hydratase 2 and (3R)-hydroxyacyl-CoA dehydrogenase activities, mammalian MFE-2 has also a sterol carrier protein type 2-like (SCP-2L) domain. In contrast, yeast MFE-2 has two (3R)-hydroxyacyl-CoA dehydrogenases, one 2-enoyl-CoA hydratase 2 and no SCP-2L domain. The physiological roles of yeast (3R)-hydroxyacyl-CoA dehydrogenases (A and B) were tested by inactivating them in turn by site-directed mutagenesis and testing the complementation of Saccharomyces cerevisiae fox-2 cells (devoid of endogenous MFE-2) with mutated variants of Sc MFE-2. Growth rates were lower for fox-2 cells expressing only a single functional domain than for those expressing the Sc MFE-2. Kinetic studies with purified Candida tropicalis MFE-2 and its mutated variants show that dehydrogenase A catalyzes the reaction more efficiently with the medium- and long-chain substrates than dehydrogenase B, which in turn is the only one active with the short chain fatty acids. The structural basis of the substrate specificity difference of these two dehydrogenases was solved by X-ray crystallography together with docking studies. Protein engineering was used to produce a stabile, homogenous recombinant protein of C. tropicalis dehydrogenases in one polypeptide. The heterodimeric structure contains the typical fold of the short-chain alcohol dehydrogenase/reductase (SDR) family. Docking studies suggest that dehydrogenase A binds medium chain-length substrates as bended, whereas short chain substrates are dislocated, because they do not reach the hydrophobic contacts needed for anchoring the substrate to the active site, but are instead attracted by L44. Dehydrogenase B has a more shallow binding pocket and thus locates the short chain-length substrates correctly for catalysis. Thus the data provide clues for structural basis of the different substrate specificities. The molecular basis of the patient mutations of MFE-2 (DBP deficiency) was studied using the recently solved crystal structures of rat (3R)-hydroxyacyl-CoA dehydrogenase, human 2-enoyl-CoA hydratase and SCP-2L. The predicted effect of the mutations on protein structure could in several cases be explained, and these data supported the conclusion that a genotype-phenotype correlation exists for DBP deficiency.