Safe drinking water is paramount to a healthy society. Close to a hundred contaminants are regulated by the government. Utilities are using chloramines to disinfect water to reduce harmful byproducts that may present themselves with the use of chlorine alone. Using chlorine and ammonia to disinfect, ammonia oxidizing bacteria can present themselves in an unsuspecting utilities distribution network. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Bibliography: leaves 235-265. / xvi, 265 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines the tumour promoting effects of the microcystins through a long-term study in which cyanobacterial extract containing a range of microcystins was given in drinking water to mice previously treated with the tumour initiator N-nitroso-N-methyluren by gavage ; and through examining the effects of pure microcystin-LR in cultured primary hepatocytes from immature mice. / Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 1998?

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. August, 2017 / The foremost aim of potable water treatment is to produce water that does not pose a health risk when consumed and/or otherwise used. Nevertheless, research has established that the quality of treated water deteriorates during distribution. The nature and extent of this deterioration varies from system to system and from time to time. The aim of this research study was to monitor the parameters that are known to significantly affect biostability and biofilm formation potential in drinking water distribution systems. Biweekly water samples were collected from thirteen sites, across a section of Johannesburg Water’s network, between September 2015 and August 2016. All samples were assayed for a suite of fifteen water quality parameters using standard methods. Heightened temperature, dearth of chlorine residuals, availability of biodegradable dissolved organic carbon (BDOC), and advanced water age all engendered the loss of biostability (instability). Biostability controlling parameters varied seasonally and spatially. Samples collected during spring and summer, in general, were most likely to be characterized by instability than samples collected during winter and autumn. Samples collected from sites RW80, RW81, RW82, RW83, RW104 and RW253 were more prone to instability compared to samples from other sites. From the results, it is clear that chlorine residuals ought to be kept above 0.2 mg/l, and, BDOC below 0.3mg/l to prevent the loss of heterotrophic stability in distributed water. BDOC concentrations can be decreased by, flushing the pipes, cleaning reservoirs regularly and by further treating feed water before distributing. Booster disinfection can be relied upon to ensure that chlorine residuals are maintained throughout the network. Apart from potential health risks, biological instability and biofilm growth can result in non-compliance with regulations. / MT2018

Tap water collected according to standard methods was examined for microbial presence. Epifluorescent diagnoses using redox probe 5-cyano-2,3ditolyl tetrazolium chloride (CTC), 4',6-diamidino-2-phenylindole (DAPI), and acridine orange (AO) were employed for direct evidence of microorganisms. Evidence of total (DAPI or AO), respiring (CTC) bacteria, and heterotrophic plate count (HPC) was determined on multiple occasions during the summer, fall, and winter 1996-1997. Pseudomonas aeruginosa, Acinetobacter sp., Bacillus licheniformis, and Methylobacterium rhodinum were isolated and identified by the API and Biolog system using GN and GP procedures. On the basis of comparisons presented in this study between the CTC method and the standard HPC procedure, it appeared that the number of CTC-reducing bacteria in the tap water samples was typically higher than that determined by HPC, indicating that many respiring bacteria detected by the CTC reduction technique fail to produce visible colonieson the agar media used. In the seasonal data obtained by the CTC method, no difference was shown among respiring bacterial counts obtained from June through January. In the examination of P. aeruginosa viability in presence of chlorine, the number of CTC-positive bacteria exceeded the number of CFU by more than 2 logs after exposure to chlorine, suggesting that reliance on HPC overestimate the efficacy of disinfection treatment. In inactivation assays using the Biolog MT plate, no sensitivity to chlorine or chloramine disinfectants was noted even at high concentration levels (5 mg/liter). Following initial drop, bacterial activities increased as contact time increased. Thus, it appears that the MT microplate provides too low a cell concentration, too great a contact time, and/or too low a concentration of tetrazolium dye within the well for successful analysis of disinfectant capability to selected bacterial strains isolated from distribution water. / Department of Biology

Made available in DSpace on 2015-04-11T13:53:53Z (GMT). No. of bitstreams: 1 rita.pdf: 2875613 bytes, checksum: 5e32b07a7fbd4413969184f90ce62026 (MD5) Previous issue date: 2009-11-03 / O abastecimento de água potável a uma população tem ação direta na saúde pública e na qualidade de vida por atuar diretamente na eliminação dos riscos vinculados ao consumo de água contaminada por microorganismos prejudiciais a saúde. Apesar do saneamento básico ser, segundo a OMS, um grande provedor na diminuição dos índices de morbidade e mortalidade infantil no mundo, o acesso da população ao serviço não é uma realidade presente para uma boa parcela da população urbana nas grandes cidades brasileiras. A problemática relativa a este assunto na cidade de Manaus serviu como fomento para uma análise na qualidade da água consumida em escolas. O estudo tem como objetivo avaliar as condições sanitárias da água de consumo humano e a situação higiênico-sanitária dos sistema de abastecimento de água e esgoto sanitário das edificações escolares. A pesquisa teve como fonte de dados os laudos microbiológicos e físico-químicos da água, assim como os relatórios de inspeção técnicas de cada escola gerados pelas ações de vigilância em saúde ambiental do projeto VISA na ESCOLA da Secretaria Municipal de Saúde. O estudo foi realizado nas escolas públicas municipais situadas na zona leste de Manaus. Os parâmetros selecionados nas ações de vigilância constituíram um Indicador Sintético Escolar (ISE) formado por 24 parâmetros (2 microbiológicos, 6 físico-químicos e 16 higiênico-sanitários). O ISE classificou as 103 escolas em 03 classes: adequada (18), regular (39) e inadequada (46), conforme as condições sanitárias da água e a situação higiênico-sanitária das instalações hidrosanitárias encontrada nas ações de fiscalização. A classe inadequada do ISE englobou as escolas com presença de coliformes totais e coliformes termotolerantes na água de consumo demonstrado que existe uma população sob risco de contrair doenças pelo consumo de água fora dos padrões da Portaria 518/2004 MS. A classificação do ISE foi espacializado em mapa temático por meio da técnica de geoprocessamento. O uso do ISE composto de dados mistos (quantitativos e qualitativos) na avaliação das condições sanitárias da água de consumo mostrou-se como uma ferramenta de auxilio apropriada para a vigilância em saúde ambiental utilizar nas ações de controle das condições sanitárias da água consumida nos estabelecimentos de ensino da rede pública municipal de Manaus

The objectives of this research were to develop a broad spectrum method for the extraction, concentration, and analysis of drinking water disinfection by products using solid phase extraction (SPE), and to determine if this method had lower detection limits and less variability than the proposed liquid-liquid extraction method, EPA Method 551. The disinfection by products investigated were halogenated nitriles, ketones, and aldehydes. The SPE method extracted and concentrated samples using the C-18 Empore Extraction Disks, and desorbed the analytes with methyl-tert-butyl ether (MTBE) as a solvent. The results showed that with the SPE method the recoveries were low (0-50%) for most compounds, and the limit of detection (LOD) values were in the range of 0.2 to 50 ug/L, which were much higher than those for EPA Method 551. The variability was also higher than for EPA Method 551. The SPE method also appeared to be concentration dependent; the recoveries decreased as analyte concentration increased. Highly saline conditions (250 g/L NaCl) resulted in low recoveries and concentration dependencies for some compounds. Even though the SPE method was easier and faster, the lower method detection limit (MDL) values and lower variability made Method 551 more preferable. Further analysis of the SPE method using a new cyclohexyl disk was also recommended. / Master of Science

The purpose of this study was to evaluate the effects of several factors which might alter the analysis of chloroform in aqueous samples by the liquid-liquid extraction (LLE) method developed by Glaze at North Texas State University. A Bendix gas chromatograph (GC) was used. The factors examined were the effect of the ionic strength of the sample on the extraction method, the relative extraction efficiency when three pentane-to-sample ratios were used, the change in the response of the GC to a set of samples during a several hours lengthy analysis, the precision of the data obtained by the analysis procedure, and the precision of analyses of aqueous chloroform standards made from one set of secondary standards. These factors were examined to aid in the development in this laboratory of an analysis program to study the role of algal extracellular metabolites as trihaloomethanes precursors. Ionic strength up to 0.0116 (strengths of algal media) did not affect the results. Few differences in the extent of linearity or extraction efficiency were detected when pentane-to-sample ratios of 1:1, 2:1, or 1:2 were used. The extraction efficiencies of the three ratios deviated 11 percent of their mean, with four values not included. The GC's response to a set of samples analyzed at the beginning and end of a nine-to-twelve hour experiment may change significantly. Standards prepared in pentane did not change during the test period. Four replicate analyses of the same sample were found to be highly precise. / Master of Science

Up-coming regulations on chlorine dioxide in drinking water treatment require low level measurement of chlorite ion (CI0₂-) and chlorate ion (CI0₃-). This research investigated analysis of CI0₂- and CI0₃-; in drinking water by flow injection analysis with iodometric detection (FIA) and ion chromatography with conductivity detection (IC). Both the FIA and IC methods were accurate for the determination of CIO₂-; and CIO₃-; in reagent water. The IC method was accurate in drinking water, however, FIA responded to chloramines and other oxidants present in drinking water causing inaccurate analysis of CIO₂-; and CIO₃-; by FIA. The two IC eluants investigated, a carbonate/bicarbonate mixture and a borate/boric acid mixture, performed well. By taking advantage of the slightly different separation abilities of each eluant, the IC method can be modified to maximize resolution of CIO₂-; and CIO₃-; in different drinking water matrices. Chlorite was unstable in chlorinated drinking water but was stable for up to three days when sodium oxalate was added and stable up to eighteen days when ethylene diamine was added as a preservative. Chlorate was stable in drinking water for up to eighteen days with or without a preservative. The propagation of errors method for determining detection limits yielded limits of detection for CIO₂- (mg/L) of 0.05 for FIA, 0.03 for the IC carbonate eluant and 0.01 for the IC borate eluant. For CIO₃- the limits of detection (mg/L) were 0.24 for FIA; 0.11 for the IC carbonate eluant and 0.02 for the borate eluant. / Master of Science

by Lai-nor Cheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 51-55). / Abstract also in Chinese. / TABLE OF CONTENTS --- p.i / ABSTRACT --- p.v / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.vii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Water Treatment Process --- p.1 / Chapter 1.2 --- Disinfectants --- p.3 / Chapter 1.3 --- THMs formation --- p.4 / Chapter 1.4 --- Various Guideline Values --- p.6 / Chapter 1.5 --- WHO Guideline Values in 1993 (used in HK) --- p.6 / Chapter 1.6 --- THM-FP --- p.7 / Chapter 1.7 --- Removal Methods --- p.7 / Chapter Chapter 2 --- "Sample Collection, Pretreatment & Storage" --- p.8 / Chapter 2.1 --- Cleaning of Sample Bottles --- p.8 / Chapter 2.2 --- Sample Collection --- p.8 / Chapter 2.3 --- Sample Pretreatment & Storage --- p.8 / Chapter Chapter 3 --- Experimental --- p.9 / Chapter 3.1 --- Analysis Methods --- p.9 / Chapter 3.1.1 --- Sample Preparation Methods --- p.9 / Chapter 3.1.1.1 --- Liquid-liquid Extraction (LLE) --- p.9 / Chapter 3.1.1.2 --- Purge & Trap (P&T) --- p.9 / Chapter 3.1.1.3 --- Static and Dynamic Headspace (HS) --- p.9 / Chapter 3.1.1.4 --- Direct Aqueous Injection --- p.10 / Chapter 3.1.2 --- GC Detectors --- p.10 / Chapter 3.1.3 --- Sensitivity --- p.10 / Chapter 3.2 --- LLE & GC/MS (SIM) --- p.11 / Chapter 3.3 --- Reagents & Apparatus --- p.12 / Chapter 3.3.1 --- Reagents --- p.12 / Chapter 3.3.2 --- Apparatus --- p.12 / Chapter 3.4 --- Procedure --- p.13 / Chapter 3.4.1 --- Pentane Extraction --- p.13 / Chapter 3.4.2 --- Instrument Configuration --- p.14 / Chapter 3.4.3 --- GC Parameters --- p.14 / Chapter 3.4.4 --- MS Parameters --- p.19 / Chapter 3.5 --- Preparation of Standards --- p.19 / Chapter 3.5.1 --- Stock Standard Solution --- p.19 / Chapter 3.5.2 --- Primary Dilution Standard --- p.20 / Chapter 3.5.3 --- Secondary Dilution Standard --- p.20 / Chapter 3.5.4 --- Calibration Standards --- p.20 / Chapter 3.6 --- Validation of the method --- p.21 / Chapter 3.6.1 --- Calibration Graphs --- p.21 / Chapter 3.6.2 --- Recovery & Precision --- p.27 / Chapter 3.6.3 --- Detection Limits --- p.30 / Chapter 3.7 --- Quality Control --- p.30 / Chapter Chapter 4 --- THMs levels and THM-FP of Tapwater --- p.31 / Chapter 4.1 --- Sample Collection Sites in HK --- p.31 / Chapter 4.2 --- Data Acquisition --- p.31 / Chapter 4.3 --- Calculations --- p.31 / Chapter 4.3.1 --- Blank Correction --- p.31 / Chapter 4.3.2 --- Calculation of THMs concentration --- p.31 / Chapter 4.3.3 --- "Mean, Standard Deviation & RSD %" --- p.32 / Chapter 4.4 --- Summary of THMs levels & THM-FP in tapwater of HK --- p.32 / Chapter 4.4.1 --- THMs levels in tapwater of HK --- p.33 / Chapter 4.4.2 --- THM-FP in tapwater of HK --- p.34 / Chapter 4.5 --- THMs levels & THM-FP in the 19 districts of HK --- p.34 / Chapter Chapter 5 --- "THMs levels of Well, Distilled & Mineral water" --- p.42 / Chapter 5.1 --- THMs levels and THM-FP of Well water --- p.42 / Chapter 5.2 --- THMs levels of Distilled water --- p.42 / Chapter 5.2 --- THMs levels of Mineral water --- p.43 / Chapter Chapter 6 --- Removal Methods --- p.44 / Chapter 6.1 --- Heating --- p.44 / Chapter 6.1.1 --- Procedure --- p.44 / Chapter 6.1.2 --- Results --- p.45 / Chapter 6.2 --- Activated Carbon Filter --- p.47 / Chapter 6.2.1 --- Procedure --- p.48 / Chapter 6.2.2 --- Results --- p.48 / Chapter Chapter 7 --- Conclusion --- p.49 / References --- p.51 / Appendix --- p.56 / Chapter A. --- Properties & Toxicity of THMs --- p.57 / Chapter B. --- Collection Date & Time of Tapwater samples & Well water samples --- p.59 / Chapter C. --- THMs levels of Tapwater in the 57 collection sites of HK --- p.62 / Chapter D. --- THM-FP of Tapwater in the 57 collection sites of HK --- p.69 / Chapter E. --- Raw data ofTHMs levels (μg/L) in Tapwater of HK --- p.76 / Chapter F. --- Raw data of THM-FP levels (μg/L) in Tapwater of HK --- p.90 / Chapter G. --- Raw data of THMs concentrations in Well，Distilled & Mineral water --- p.104 / Chapter H. --- Specification of Activated Carbon Filter --- p.106 / Chapter I.(1) --- Mass Spectrum of Chloroform --- p.108 / Chapter (2) --- Mass Spectrum of Chlorodibromomethane --- p.109 / Chapter (3) --- Mass Spectrum of Bromodichloromethane --- p.110 / Chapter (4) --- Mass Spectrum of Bromoform --- p.111

Irradiation with ultraviolet (UV) light is used for the disinfection of bacterial contaminants in the production of potable water, and in the treatment of selected wastewaters. However, efficacy of UV disinfection is limited by the combined effect of suspended solids concentration and UV absorbance. Limited published UV disinfection data are available that account for the combined effects of UV dose, suspended solids concentration and UV absorbance. This present lack of a rigorous quantitative understanding of the kinetics of UV disinfection limits process optimisation and wider application of UV treatment. The development and validation of an adequate model to describe UV disinfection kinetics presented in this thesis can therefore be justified by an increased confidence of reliability of design for UV disinfection. Using the published data of Nguyen (1999), four established model forms were assessed to account for the combined effect of suspended solids and/or soluble UV absorbing compounds, and UV dose on the efficacy of disinfection. The four model forms were: a log-linear form, Davey Linear-Arrhenius (DL-A), Square-Root (or Ratkowsky- Belehradek) and a general nth order Polynomial (nOP) form that was limited to a third order. Criteria for assessment of an adequate predictive model were established including: accuracy of predicted against observed values, percent variance accounted for (%V), and; appraisal of residuals. The DL-A model was shown to best fit the data for UV disinfection of Escherichia coli (ATCC 25922); followed by the nOP, log-linear and Square-Root forms. However, the DL-A form must be used in conjunction with a first-order chemical reaction equation, and was shown to predict poorly at high experimental values of UV dose (> 40,000 μWs cm-2). The DL-A model was not amenable to extrapolation beyond the observed UV dose range. To overcome the shortcomings of the Davey Linear-Arrhenius model synthesis of two new, non-linear model forms was undertaken. The two models were a modified exponentially damped polynomial (EDPm) and a form based on the Weibull probability distribution. The EDPm model has three terms: a rate coefficient (k), a damping coefficient (λ), and; a breakpoint dose ([dose]B). The rate coefficient governs the initial rate of disinfection prior to the onset of tailing, whilst the breakpoint is the UV dose that indicates the onset of tailing. The damping coefficient controls curvature in the survivor curve. The Weibull model has just two terms: a dimensionless scale parameter (β0), and; a shape parameter (β1). The scale parameter represents the level of disinfection in the tail of the survivor curve (as log10 N/N0), whilst the shape parameter governs the degree of curvature of the survivor data. Each model was assessed against the independent and published UV disinfection data of Nelson (2000) for treatment of faecal coliforms in a range of waste stabilisation pond effluents. Both models were found to be well suited to account for tailing in these UV disinfection data. Overall, the EDPm model gave a better fit to the data than the Weibull model form. To rigorously validate the suitability of the new EDPm and Weibull models a series of experimental trials were designed and carried out in a small-scale pilot UV disinfection unit. These trials included data determined specifically at low values of UV dose (<10,000 μWs cm-2) to fill the gap in the experimental data of Nguyen (1999). The experimental trials were carried out using a commercially available, UV disinfection unit (LC5TM from Ultraviolet Technology of Australasia Pty Ltd). Purified water contaminated with Escherichia coli (ATCC 25922) with a range of feed water flow rates (1 to 4 L min-1) was used. E. coli was selected because it is found in sewage, or water contaminated with faecal material, and is used as an indicator for the presence of enteric pathogens. E. coli should not be present in potable water. The hydrodynamics of water flow within the disinfection unit were established using digital video photography of dye trace studies with Methylene Blue. Nominal UV dose (2,700 to 44,200 μWs cm-2) was controlled by manipulating the flow rate of feed water through the UV disinfection unit (i.e. residence time), or by varying the exposed length of the control volume of the disinfection unit. The transmittance of the feed water (at 254 nm) was adjusted by the addition of either a soluble UV absorbing agent (International RoastTM instant coffee powder; 0.001 to 0.07 g L-1), or by addition of suspended matter as diatomaceous earth (Celite 503TM; 0.1 to 0.7 g L-1, with a median particle size of 23 μm). The absorbing agent (instant coffee), when in a comparable concentration, was found to produce a greater reduction in water transmission than the suspended material (Celite 503TM). It therefore contributed to a greater reduction in the initial rate of disinfection. Neither agent was found to produce a systematic reduction in the observed efficacy of disinfection however. Experimental results highlight that in the absence of soluble absorbing agents, or suspended solids, the initial rate of disinfection is higher when fewer viable bacteria are initially present. Both the new EDPm and Weibull forms gave a good fit to the experimental data. The EDPm better fitted the data on the basis of residual sum-of-squares (0.03 to 2.13 for EDPm cf. 0.16 to 4.37 for the Weibull form). These models are both of a form suitable for practical use in modelling UV disinfection data. Results of this research highlight the impact of water quality, as influenced by the combined effect of UV dose, suspended solids concentration and UV absorbance, on small-scale UV disinfection for potable water production. Importantly, results show that the concentration of soluble UV absorbing agents and suspended solids are not in themselves sufficient criteria on which to base assessment of efficacy of UV disinfection / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342403 / Thesis (M.Eng.Sc.) - University of Adelaide, School of Chemical Engineering, 2008