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Title: Molecular Size Distributions of Heavy Metals in Lake Washington.
Creator: Andrews, William B., Taylor, James S., Engineering
Abstract / Description: University of Central Florida College of Engineering Thesis; Four untreated and one magnesium treated water samples from Lake Washington, the potable water source for the city of Melbourne, Florida, were collected and analyzed for As, Cd, Cr, Cu, Fe, Pb, Ni, Zn, Mb, Ca, and color on the basis of molecular weight distribution. Molecular weight distributions of the samples were obtained using a Millipore ultrafiltration system and filters in the following sizes: 106, 105, 2.5 x 104, 104, and...
Show moreUniversity of Central Florida College of Engineering Thesis; Four untreated and one magnesium treated water samples from Lake Washington, the potable water source for the city of Melbourne, Florida, were collected and analyzed for As, Cd, Cr, Cu, Fe, Pb, Ni, Zn, Mb, Ca, and color on the basis of molecular weight distribution. Molecular weight distributions of the samples were obtained using a Millipore ultrafiltration system and filters in the following sizes: 106, 105, 2.5 x 104, 104, and 103 nominal molecular weight limits (nmwl). color causing materials in the untreated samples were found to be located in the molecular weight fraction greater than 2.5 x 104 nmwl. The majoity of the metals concentrations (approximately greater than 80%) were also found to be located in the molecular weight fraction greater than 2.5 x 104 nmwl. Analysis of the magnesium treated (for maximum color removal) sample showed higher concentrations of metals passing the respective filter sizes as opposed to the untreated samples indicating less complexation or smaller molecular complexes of the metals. Thus, a fairly strong correlation betwee heavy metals concentrations and colorin the Lake Washington samples was indicated.
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Date Issued: 1979
Identifier: CFR0008138, ucf:52945
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFR0008138

Title: The effect of varying temperature, flux and pretreatment on the microfiltration of Lake Michigan water.
Creator: Kopp, Karen Linda, Taylor, James S., Engineering
Abstract / Description: University of Central Florida College of Engineering Thesis; This study investigated microfiltration of Lake Michigan Water for the production of drinking water. A 60 gpm Memcor microfiltration pilot plant was operated for nine months at Manitowoc, Wisconsin to determine and model the performance characteristics of a microfiltration pilot plant for varying surface water conditions. Statistical regression and modeling was used to determine and develop quantitative relationships between time of...
Show moreUniversity of Central Florida College of Engineering Thesis; This study investigated microfiltration of Lake Michigan Water for the production of drinking water. A 60 gpm Memcor microfiltration pilot plant was operated for nine months at Manitowoc, Wisconsin to determine and model the performance characteristics of a microfiltration pilot plant for varying surface water conditions. Statistical regression and modeling was used to determine and develop quantitative relationships between time of operation and several operational variables for water quality and productivity. Modifications of Darcy's Law and flux decline data were used to develop a model relating temperature and flux to cleaning frequency. Statistical hypothesis testing and associated modeling were used to determine if relationships existed between the water quality and the independent operating variables affecting microfiltration. The study demonstrated that the filtered water turbidity or particle count did not carry with the flux or the influent water temperature and that the degree of turbidity or particle count removal was dependent on the raw water turbidity or particle count. Direct filtration of an alum pretreated feed water was found to greatly increase time of operation between cleanings for temperatures below 48Â°F. As expected the size exclusion membrane process was found to have no effect on dissolved of diffusion controlled solute rejection. the investigation found the turbidity and particle counts of the microfiltered water was less than the same for the finished water produced by the conventional alum coagulation, sedimentation and filtration process. The investigation demonstrated that microfiltration could be used to consistently produce a drinking water that met or exceeded state or federal requirements at Manitowoc. Based on the results of this investigation, a recommendation was made to use microfiltration as the treatment process of choice for the treatment of Lake Michigan Water.
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Date Issued: 1997
Identifier: CFR0010872, ucf:53052
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFR0010872

Title: WATER QUALITY VARIATIONS DURING NITRIFICATION IN DRINKING WATER DISTRIBUTION SYSTEMS.
Creator: Webb, David W, Taylor, James S., University of Central Florida
Abstract / Description: This thesis documents the relationship among the major water quality parametersduring a nitrification episode. Nitrification unexpectedly occurred in a chloraminated pilotdrinking water distribution system practicing with a 4.0 mg/L as Cl2 residual dosed at 4.5:1Cl2:NH3-N. Surface, ground and sea water were treated and disinfected withmonochloramines to produce finished water quality similar to regional utility water quality.PVC, galvanized, unlined cast iron and lined iron pipes were...
Show moreThis thesis documents the relationship among the major water quality parametersduring a nitrification episode. Nitrification unexpectedly occurred in a chloraminated pilotdrinking water distribution system practicing with a 4.0 mg/L as Cl2 residual dosed at 4.5:1Cl2:NH3-N. Surface, ground and sea water were treated and disinfected withmonochloramines to produce finished water quality similar to regional utility water quality.PVC, galvanized, unlined cast iron and lined iron pipes were harvested from regionaldistribution systems and used to build eighteen pilot distribution systems (PDSs). The PDSswere operated at a 5-day hydraulic residence time (HRT) and ambient temperatures.As seasonal temperatures increased the rate of monochloramine dissipation increaseduntil effluent PDS residuals were zero. PDSs effluent water quality parameters chloraminesresidual, dissolved oxygen, heterotrophic plate counts (HPCs), pH, alkalinity, and nitrogenspecies were monitored and found to vary as expected by stoichiometry associated withtheoretical biological reactions excepting alkalinity. Nitrification was confirmed in thePDSs. The occurrence in the PDSs was not isolated to any particular source water.Ammonia for nitrification came from degraded chloramines, which was common among allfinished waters. Consistent with nitrification trends of dissolved oxygen consumption,ammonia consumption, nitrite and nitrate production were clearly observed in the PDSs bulkwater quality profiles. Trends of pH and alkalinity were less apparent. To controlnitrification: residual was increased to 4.5 mg/L as Cl2 at 5:1 Cl2:NH3-N dosing ratio, and theHRT was reduced from 5 to 2 days. Elimination of the nitrification episode was achievedafter a 1 week free chlorine burn.
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Date Issued: 2004
Identifier: CFE0000063, ucf:46118
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000063

Title: EFFECT OF SOURCE WATER BLENDING ON COPPER RELEASE IN PIPE DISTRIBUTION SYSTEM: THERMODYNAMIC AND EMPIRICAL MODELS.
Creator: Xiao, Weizhong, Taylor, James S., University of Central Florida
Abstract / Description: This dissertation focuses on copper release in drinking water. Qualitative and quantitative assessment of Cu and Fe corrosion by process water quality was assessed over one year in a field study using finished waters produced from seven different treatment process and eighteen pilot distribution systems (PDSs) that were made from unlined cast iron and galvanized steel pipes, and lined cement and PVC pipes taken from actual distribution systems. Totally seven different waters were studied,...
Show moreThis dissertation focuses on copper release in drinking water. Qualitative and quantitative assessment of Cu and Fe corrosion by process water quality was assessed over one year in a field study using finished waters produced from seven different treatment process and eighteen pilot distribution systems (PDSs) that were made from unlined cast iron and galvanized steel pipes, and lined cement and PVC pipes taken from actual distribution systems. Totally seven different waters were studied, which consisted of three source waters: groundwater, surface, and simulated brackish water designated as G1, S1, and RO. With certain pre-established blending ratios, these three waters were blended to form another three waters designated as G2, G3, and G4. Enhanced surface water treatment was CFS, ozonation and GAC filtration, which was designated as S1. The CFS surface water was nanofiltered, which is S2. All seven finished waters were stabilized and chloraminated before entering the PDSs. Corrosion potential was compared qualitatively and quantitatively for all seven waters by monitoring copper and iron release from the PDSs. This dissertation consists of four major parts.(1) Copper corrosion surface characterization in which the solid corrosion products formed in certain period of exposure to drinking water were tried to be identified with kinds of surface techniques. Surface characterization indicated that major corrosion products consists of cuprite (Cu2O) as major underneath corrosion layer and tenorite (CuO), cupric hydroxide (Cu(OH)2) on the top surface. In terms of dissolution/precipitation mechanism controlling the copper concentration in bulk solution, cupric hydroxide thermodynamic model was developed.(2) Theoretical thermodynamic models were developed to predict the copper release level quantitatively based on controlling solid phases identified in part (1). These models are compared to actual data and relative assessment is made of controlling solid phases. (3) Non-linear and linear regression models were developed that accommodated the release to total copper for varying water quality. These models were verified using independent data and provide proactive means of assessing and controlling copper release in a varying water quality environment. (4) Simulation of total copper release was conducted using all possible combinations of water quality produced by blending finished waters from ground, surface and saline sources, which involves the comparison of copper corrosion potentials among reverse osmosis, nanofiltration, enhanced coagulation, lime softening, and conventional drinking water treatment.
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Date Issued: 2004
Identifier: CFE0000042, ucf:46069
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000042

Title: MODELING FREE CHLORINE AND CHLORAMINE DECAY IN A PILOT DISTRIBUTION SYSTEM.
Creator: Arevalo, Jorge, Taylor, James, University of Central Florida
Abstract / Description: The purpose of this study was to identify the effect that water quality, pipe material, pipe size, flow conditions and the use of corrosion inhibitors would have on the rate of free chlorine and chloramine decay in distribution systems. Empirical models were developed to predict the disinfectant residual concentration with time based on the parameters that affected it. Different water treatment processes were used to treat groundwater and surface water to obtain 7 types of finished waters...
Show moreThe purpose of this study was to identify the effect that water quality, pipe material, pipe size, flow conditions and the use of corrosion inhibitors would have on the rate of free chlorine and chloramine decay in distribution systems. Empirical models were developed to predict the disinfectant residual concentration with time based on the parameters that affected it. Different water treatment processes were used to treat groundwater and surface water to obtain 7 types of finished waters with a wide range of water quality characteristics. The groundwater was treated either by conventional treatment by aeration (G1) or softening (G2) or high pressure reverse osmosis (RO) and the surface water was treated either by enhanced coagulation, ozonation and GAC filtration (CSF-O3-GAC or S1) or an integrated membrane system (CSF-NF or S2). The remaining two water types were obtained by treating a blend of G1, S1 and RO by softening (S2) and nanofiltration (G4). A pilot distribution systems (PDS) consisting of eighteen (18) lines was built using old pipes obtained from existing distribution system. The pipe materials used were polyvinyl chloride (PVC), lined cast iron (LCI), unlined cast iron (UCI) and galvanized steel (G). During the first stage of the study, the 7 types of water were blended and fed to the PDS to study the effect of feed water quality changes on PDS effluent water quality, and specifically disinfectant residual. Both free chlorine and chloramines were used as disinfectant and the PDSs were operated at hydraulic retention times (HRT) of 2 and 5 days. The PDSs were periodically tested for free and combined chlorine, organic content, temperature, pH, turbidity and color. The data obtained were used to develop separate models for free chlorine and chloramines. The best fit model was a first-order kinetic model with respect to initial disinfectant concentration that is dependent on the pipe material, pipe diameter and the organic content and temperature of the water. Turbidity, color and pH were found to be not significant for the range of values observed. The models contain two decay constants, the first constant (KB) accounts for the decay due to reaction in the bulk liquid and is affected by the organics and temperature while the second constant, KW, represents the reactions at the pipe wall and is affected by the temperature of the water and the pipe material and diameter. The rate of free chlorine and chloramine decay was found to be highly affected by the pipe material, the decay was faster in unlined metallic pipes (UCI and G) and slower in the synthetic (PVC) and lined pipes (LCI). The models showed that the rate of disinfectant residual loss increases with the increase of temperature or the organics in the water irrespective of pipe material. During the second part of the study, corrosion control inhibitors were added to a blend of S1, G1 and RO that fed all the hybrid PDSs. The inhibitors used were: orthophosphate, blended ortho-polyphosphate, zinc orthophosphate and sodium silicate. Three PDSs were used for each inhibitor type, for a total of 12 PDSs, to study the effect of low, medium and high dose on water quality. Two PDSs were used as control, fed with the blend without any inhibitor addition. The control PDSs were used to observe the effect of pH control on water quality and compare to the inhibitor use. One of the control PDSs (called PDS 13) had the pH adjusted to be equal to the saturation pH in relation to calcium carbonate precipitation (pHs) while the pH of the other control PDS (PDS 14) was adjusted to be 0.3 pH units above the pHs. The disinfectant used for this part of the study was chloramine and the flow rates were set to obtain a HRT of 2 days. The chloramine demand was the same for PDS 14 and all the PDSs receiving inhibitors. PDS 13 had a chloramine demand greater than any other PDS. The lowest chloramine demand was observed in PDS 12, which received silicate inhibitor at a dose of 12 mg/L, and presented the highest pH. The elevation of pH of the water seems to reduce the rate of decay of chloramines while the use of corrosion inhibitors did not have any effect. on the rate of chloramine decay. The PDS were monitored for chloramine residual, temperature, pH, phosphate, reactive silica, and organic content. Empirical models were developed for the dissipation of chloramine in the pilot distribution systems as a function of time, pipe material, pipe diameter and water quality. Terms accounting for the effect of pH and the type and dose of corrosion inhibitor were included in the model. The use of phosphate-based or silica-based corrosion inhibitors was found to have no effect on the rate of chloramine dissipation in any of the pipe materials. Only the increase of pH was found to decrease the rate of chloramine decay. The model to best describe the decay of chloramine in the pilot distribution systems was a first-order kinetic model containing separate rate constants for the bulk reactions, pH effect and the pipe wall reactions. The rate of chloramine decay was dependent on the material and diameter of the pipe, and the temperature, pH and organic content of the water. The rate of chloramine decay was low for PVC and LCI, and more elevated in UCI and G pipes. Small diameter pipes and higher temperatures increase the rate of chlorine decay irrespective of pipe material. Additional experiments were conducted to evaluate the effect of flow velocity on chloramine decay in a pilot distribution system (PDS) for different pipe materials and water qualities. The experiments were done using the single material lines and the flow velocity of the water was varied to obtain Reynolds' numbers from 50 to 8000. A subset of experiments included the addition of blended orthophosphate corrosion inhibitor (BOP) at a dose of 1.0 mg/L as P to evaluate the effect of the inhibitor on chloramine decay. The effect of Reynolds' number on the overall chloramine decay rate (K) and the wall decay rate constant (W) was assessed for PVC, LCI, UCI, and G pipes. PVC and LCI showed no change on the rate of chloramine decay at any flow velocity. UCI and G pipes showed a rapid increase on the wall decay rate under laminar conditions (Re < 500) followed by a more gradual increase under fully turbulent flow conditions (Re > 2000). The use of the BOP inhibitor did not have an effect on the rate of chloramine decay for any of the pipe materials studied. Linear correlations were developed to adjust the rate of chloramine decay at the pipe wall for UCI and G depending on the Reynolds' number.
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Date Issued: 2007
Identifier: CFE0001863, ucf:47400
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001863

Title: AN INVESTIGATION OF SIZE EXCLUSION AND DIFFUSION CONTROLLED MEMBRANE FOULING.
Creator: Hobbs, Colin, Taylor, James, University of Central Florida
Abstract / Description: The reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased...
Show moreThe reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased chemical cleaning frequencies, and increased membrane replacement frequencies. The most significant practical implication of membrane fouling is increased operating and maintenance costs. As such, membrane fouling must be properly managed to ensure successful and efficient operation of membrane systems. This document presents four independent studies regarding the fouling of size exclusion and diffusion controlled membranes. A brief description of each study is presented below. The first study systematically investigated the fouling characteristics of various thin film composite polyamide reverse osmosis (RO) and nanofiltration (NF) membranes using a high organic surficial groundwater obtained from the City of Plantation, Florida. Prior to bench-scale fouling experiments, surface properties of the selected RO and NF membranes were carefully analysed in order to correlate the rate and extent of fouling to membrane surface characteristics, such as roughness, charge and hydrophobicity. More specifically, the surface roughness was characterized by atomic force microscopy, while the surface charge and hydrophobicity of the membranes were evaluated through zeta potential and contact angle measurements, respectively. The results indicated that membrane fouling became more severe with increasing surface roughness, as measured by the surface area difference, which accounts for both magnitude and frequency of surface peaks. Surface roughness was correlated to flux decline; however, surface charge was not. The limited range of hydrophobicity of the flat sheet studies prohibited conclusions regarding the correlation of flux decline and hydrophobicity. Mass loading and resistance models were developed in the second study to describe changes in solvent mass transfer (membrane productivity) over time of operation. Changes in the observed solvent mass transfer coefficient of four low pressure reverse osmosis membranes were correlated to feed water quality in a 2,000 hour pilot study. Independent variables utilized for model development included: temperature, initial solvent mass transfer coefficient, water loading, ultraviolet absorbance, turbidity, and monochloramine concentration. Models were generated by data collected throughout this study and were subsequently used to predict the solvent mass transfer coefficient. The sensitivity of each model with respect to monochloramine concentration was also analyzed. In the third study, mass loading and resistance models were generated to predict changes in solvent mass transfer (membrane productivity) with operating time for three reverse osmosis and nanofiltration membranes. Variations in the observed solvent mass transfer coefficient of these membranes treating filtered secondary effluent were correlated to the initial solvent mass transfer coefficient, temperature, and water loading in a 2,000 hour pilot study. Independent variables evaluated during model development included: temperature, initial solvent mass transfer coefficient, water loading, total dissolved solids, orthophosphorous, silica, total organic carbon, and turbidity. All models were generated by data collected throughout this study. Autopsies performed on membrane elements indicated membranes that received microfiltered water accumulated significantly more dissolved organic carbon and polysaccharides on their surface than membranes that received ultrafiltered water. Series of filtration experiments were systematically performed to investigate physical and chemical factors affecting the efficiency of backwashing during microfiltration of colloidal suspensions in the fourth study. Throughout this study, all experiments were conducted in dead-end filtration mode utilizing an outside-in, hollow-fiber module with a nominal pore size of 0.1 µm. Silica particles (mean diameter ~ 0.14 µm) were used as model colloids. Using a flux decline model based on the Happel's cell for the hydraulic resistance of the particle layer, the cake structure was determined from experimental fouling data and then correlated to backwash efficiency. Modeling of experimental data revealed no noticeable changes in cake layer structure when feed particle concentration and operating pressure increased. Specifically, the packing density of the cake layer (l-cake porosity) in the cake layer ranged from 0.66 to 0.67, which corresponds well to random packing density. However, the particle packing density increased drastically with ionic strength. The results of backwashing experiments demonstrated that the efficiency of backwashing decreased significantly with increasing solution ionic strength, while backwash efficiency did not vary when particle concentration and operating pressure increased. This finding suggests that backwash efficiency is closely related to the structure of the cake layer formed during particle filtration. More densely packed cake layers were formed under high ionic strength, and consequently less flux was recovered per given backwash volume during backwashing.
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Date Issued: 2007
Identifier: CFE0001854, ucf:47366
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001854

Title: REVERSION OF POLY-PHOSPHATES TO ORTHO-PHOSPHATES IN WATER DISTRIBUTION SYSTEMS.
Creator: shekhar, avinash, taylor, james, University of Central Florida
Abstract / Description: Orthophosphates and polyphosphates are rarely present at significant levels in raw water source but are purposefully added to the water in various forms to inhibit corrosion, iron oxidation (red water), or calcium carbonate precipitation (scale formation). Orthophosphates serve as building blocks for polyphosphates, which includes structures in linear chain, branched chains (metaphosphate) and "glassy" polyphosphate polymers. The advantage of polyphosphates over ortho phosphates lies in the...
Show moreOrthophosphates and polyphosphates are rarely present at significant levels in raw water source but are purposefully added to the water in various forms to inhibit corrosion, iron oxidation (red water), or calcium carbonate precipitation (scale formation). Orthophosphates serve as building blocks for polyphosphates, which includes structures in linear chain, branched chains (metaphosphate) and "glassy" polyphosphate polymers. The advantage of polyphosphates over ortho phosphates lies in the fact that they slowly revert to orthophosphates and thus provide corrosion inhibition action over longer period of time in distribution systems. A study was completed for Tampa Bay Water on water distribution systems in a changing water quality environment. Blended orthophosphates was used as one of the corrosion inhibitors to study its effects on metal release and thus justify its application in comparison to other corrosion inhibitors like orthophosphates, zinc orthophosphates and silicates. This work focuses on the study of reversion of polyphosphates to ortho phosphates. A first-order model was developed that quantifies reversion as a function of the hydraulic residence time and initial poly phosphate concentration. The same model was used in two different forms – one for the hybrid lines and the other for single material lines. The results from single material lines (estimated by a non linear least square regression using ANOVA) showed that the reversion rate was highest for galvanized pipe followed by unlined cast iron, lined cast iron and the lowest rate in PVC. The first-order reversion rate constant in PVC was almost two log orders less than galvanized line. A high first-order rate constant for the galvanized pipe could be attributed to a rougher surface, large surface area, reaction with the wall surface, pipe material or a combination of these effects. The results from the hybrid PDSs (estimated by an algebraic manipulation of the first-order reaction) substantially agree with the results obtained from the single material lines, with the exception of the PVC material. The data from the hybrid lines confirms that the reversion rate constant is greatest for exposure to galvanized pipe materials, but the hybrid data indicate that the rate constant associated with PVC is somewhat larger than the constants determined for either LCI or UCI. Once an overall first-order rate expression was established, efforts were made to find a relation between polyphosphate reversions with bulk water quality. None of the major water quality parameters were found to significantly affect the reversion. This observation may be attributable to a similar water quality over the study duration. A positive correlation was found between first-order reversion rate constant and temperature. An empirical equation (modified Arrhenius equation) that relates the first-order reversion rate constant with temperature was developed that showed a strong sensitivity to temperature. The results from this study could be used to predict the stability of polyphosphates in distribution systems with varying pipe materials and temperature.
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Date Issued: 2007
Identifier: CFE0001832, ucf:47350
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001832

Title: VERIFICATION OF PILOT-SCALE IRON RELEASE MODELS.
Creator: Glatthorn, Stephen, Taylor, James, University of Central Florida
Abstract / Description: A model for the prediction of color release from a pilot distribution system was created in 2003 by Imran. This model allows prediction of the release of color from aged cast iron and galvanized steel pipes as a function of water quality and hydraulic residence time. Color was used as a surrogate measurement for iron, which exhibited a strong linear correlation. An anomaly of this model was an absence of a term to account for pH, due to the influent water being well stabilized. A new study...
Show moreA model for the prediction of color release from a pilot distribution system was created in 2003 by Imran. This model allows prediction of the release of color from aged cast iron and galvanized steel pipes as a function of water quality and hydraulic residence time. Color was used as a surrogate measurement for iron, which exhibited a strong linear correlation. An anomaly of this model was an absence of a term to account for pH, due to the influent water being well stabilized. A new study was completed to evaluate the effectiveness of corrosion inhibitors against traditional adjustment. Two control lines were supplied with nearly same water qualities, one at pH close to pHs and one at pH well above pHs. The resulting data showed that effluent iron values were typically greater in the line with lower pH. The non-linear color model by Imran shows good agreement when the LSI was largely positive, but underpredicted the color release from the lower LSI line. A modification to the Larson Ratio proposed by Imran was able to give a reasonable agreement to the data at lower LSI values. LSI showed no definite relation to iron release, although a visual trend of higher LSI mitigating iron release can be seen. An iron flux model was also developed on the same pilot system by Mutoti. This model was based on a steady state mass balance of iron in a pipe. The constants for the model were empirically derived from experiments at different hydraulic conditions with a constant water quality. Experiments were assumed to reach steady state at 3 pipe volumes due to the near constant effluent turbidity achieved at this point. The model proposes that the iron flux under laminar flow conditions is constant, while the iron flux is linearly related to the Reynolds Number under turbulent conditions. This model incorporates the color release models developed by Imran to calculate flux values from different water qualities. A limited number of experiments were performed in the current study using desalinated and ground water sources at Reynolds Numbers ranging from 50 to 200. The results of these limited experiments showed that the iron flux for cast iron pipe was approximately one-half of the predicted values from Mutoti. This discrepancy may be caused by the more extensive flushing of the pipes performed on the current experiments which allowed attainment of a true steady state. Model changes were proposed to distinguish between near stagnant flow and the upper laminar region, with the upper laminar region showing a slight linear increase. Predictions using the galvanized flux model were not accurate due to an inferior color release model that was developed for galvanized pipes. The model exhibits a high dependence on sulfate concentrations, but concentrations of sulfates in the current experiments were low. This led to low predicted flux values when the actual data showed otherwise. A new galvanized model was developed from a combination of data from the original and current experiments. The predicted flux values using the new model showed great improvement over the old model, but the new model database was limited and the resulting model was not able to be independently tested.
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Date Issued: 2007
Identifier: CFE0001704, ucf:47332
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001704

Title: IMPACT OF ZINC ORTHOPHOSPHATE INHIBITOR ONDISTRIBUTION SYSTEM WATER QUALITY.
Creator: Guan, Xiaotao, Taylor, James, University of Central Florida
Abstract / Description: This dissertation consists of four papers concerning impacts of zinc orthophosphate (ZOP) inhibitor on iron, copper and lead release in a changing water quality environment. The mechanism of zinc orthophosphate corrosion inhibition in drinking water municipal and home distribution systems and the role of zinc were investigated. Fourteen pilot distribution systems (PDSs) which were identical and consisted of increments of PVC, lined cast iron, unlined cast iron and galvanized steel pipes were...
Show moreThis dissertation consists of four papers concerning impacts of zinc orthophosphate (ZOP) inhibitor on iron, copper and lead release in a changing water quality environment. The mechanism of zinc orthophosphate corrosion inhibition in drinking water municipal and home distribution systems and the role of zinc were investigated. Fourteen pilot distribution systems (PDSs) which were identical and consisted of increments of PVC, lined cast iron, unlined cast iron and galvanized steel pipes were used in this study. Changing quarterly blends of finished ground, surface and desalinated waters were fed into the pilot distribution systems over a one year period. Zinc orthophosphate inhibitor at three different doses was applied to three PDSs. Water quality and iron, copper and lead scale formation was monitored for the one year study duration. The first article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on surface characteristics of iron corrosion products in a changing water quality environment. Surface compositions of iron surface scales for iron and galvanized steel coupons incubated in different blended waters in the presence of ZOP inhibitor were investigated using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) / Energy Dispersive X-ray Spectroscopy (EDS). Based on surface characterization, predictive equilibrium models were developed to describe the controlling solid phase and mechanism of ZOP inhibition and the role of zinc for iron release. The second article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total iron release in a changing water quality environment. Development of empirical models as a function of water quality and ZOP inhibitor dose for total iron release and mass balances analysis for total zinc and total phosphorus data provided insight into the mechanism of ZOP corrosion inhibition regarding iron release in drinking water distribution systems. The third article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total copper release in a changing water quality environment. Empirical model development was undertaken for prediction of total copper release as a function of water quality and inhibitor dose. Thermodynamic models for dissolved copper based on surface characterization of scale that were generated on copper coupons exposed to ZOP inhibitor were also developed. Surface composition was determined by X-ray Photoelectron Spectroscopy (XPS). The fourth article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total lead release in a changing water quality environment. Surface characterization of lead scale on coupons exposed to ZOP inhibitor by X-ray Photoelectron Spectroscopy (XPS) was utilized to identify scale composition. Development of thermodynamic model for lead release based on surface analysis results provided insight into the mechanism of ZOP inhibition and the role of zinc.
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Date Issued: 2007
Identifier: CFE0001931, ucf:47453
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001931

Title: USING ELECTROCHEMICAL MONITORING TO PREDICT METAL RELEASE IN DRINKING WATER DISTRIBUTION SYSTEMS.
Creator: Vaidya, Rajendra, Taylor, James, University of Central Florida
Abstract / Description: ABSTRACT Corrosion of distribution system piping and home plumbing materials is a major concern in the water community. Iron release adverse affects aesthetic water quality and the release of copper and lead is regulated by the Lead and Copper rule (LCR) and can adversely affect consumer health. Corrosion control is typically done by pH regulation and/or addition of corrosion inhibitors. Monitoring of corrosion control is typically done after the fact by monitoring metal release, functional...
Show moreABSTRACT Corrosion of distribution system piping and home plumbing materials is a major concern in the water community. Iron release adverse affects aesthetic water quality and the release of copper and lead is regulated by the Lead and Copper rule (LCR) and can adversely affect consumer health. Corrosion control is typically done by pH regulation and/or addition of corrosion inhibitors. Monitoring of corrosion control is typically done after the fact by monitoring metal release, functional group concentration of the selected chemical species or water quality. Hence, the associated laboratory analyses create a significant delay prior to the assessment of corrosion in drinking water systems. As corrosion in drinking water systems is fundamentally an electrochemical process, measurement of the electrical phenomena associated with corrosion can be use for real-time corrosion monitoring. This dissertation focuses on using parameters associated with electrochemical corrosion monitoring (EN) measurements in a field facility to predict and control the release of Iron, Copper and Lead in finished waters produced from ground, surface and saline sources with and without usage of corrosion inhibitors. EN data has not been used previously to correlate water quality and metal release; hence the use of EN data for corrosion control in drinking water systems has not been developed or demonstrated. Data was collected over a one year period from a large field facility using finished waters that are distributed to each of the fourteen pilot distribution systems (PDSs), corrosion loops and Nadles each. The PDSs have been built from aged pipes taken from existing distribution systems and contain links of PVC, lined cast Iron, unlined cast Iron and galvanized Steel pipe. The effluent for each PDS was split in two parts. One was delivered to the corrosion loops which are made from coiled copper pipe with lead-tin coupon inserted inside each loop and the other was delivered to the Nadles which housed the EN probes with electrodes for Fe or Cu or Pb-Sn. Finished water quality was monitored in and out of each PDS and total and dissolved Copper and Lead were monitored out of each corrosion loop. Photographs, scanning electron microscope (SEM) micrographs and energy disruptive x-ray spectroscopy (EDAX) conducted on all EN electrodes. EN electrodes showed dark brown to blackish voluminous scales for Fe, and EDAX revealed occurrence of two scales in distinct areas for all Fe electrodes; one comprised of porous, spongy looking structures and scales with more Fe content where the other had denser and more compact scales richer in Ca and P or Si. Cu electrodes had an orange to dark brown thin scale with blue green spots. Small pits were consistently observed mostly in the centre of such blue green spots which were identified as copper carbonates. The Pb electrodes visually showed a thin shiny transparent film with a surface very similar to the unexposed electrodes. Numerous pits were visually for pH controls and not seen for inhibitors; but SEM revealed that all electrodes had pits but the inhibitors reduced number and size of pits compared with pH controls. Thin hexagonal hydrocerussite plates were observed to occur in distinct growth areas and the presence of P or Si inhibitor seemed to increase the occurrence of hydrocerussite. Both Fe & Pb release were mostly in the particulate form while Cu release was mostly in the dissolved form. Total and dissolved Fe, Cu and Pb release models using EN parameters were developed by nonlinear regression. Fe release increased with localized corrosion (PF) and the EN model predicts that Fe release can be effectively controlled to the same degree by pH elevation or inhibitors. Cu release increased with general corrosion (LPRCR) and was also influenced by localized corrosion (ECNCR). However general corrosion was more significant for copper release which was mostly in the dissolved form. Pb release was depended on both general corrosion (LPRCR & HMCR) and localized corrosion (PF). The EN models predict that both Cu and Pb release is highest for pH control and all inhibitors reduced Cu and Pb release, which is consistent with the data. Inhibitors ranked by increasing effectiveness for reducing both Cu and Pb release are pH elevation, Si, ZOP, OP and BOP. EN monitoring is faster and less labor intensive than water quality monitoring and represents a significant advance for controlling metal release in drinking water distribution systems. The EN models were found to be comparable to water quality models developed from this study for metal release, and since EN is a real-time technique it offers a tremendous advantage over traditional water quality sampling techniques. Remote access of EN monitoring equipment is possible and the system requires little to no maintenance with the exception of a power supply or battery. The rapid turn around of corrosion rates from EN can be used to estimate metal release in drinking water proactively and mitigating measures can be implemented before the full adverse impacts are realized.
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Date Issued: 2007
Identifier: CFE0001953, ucf:47430
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001953

Title: MECHANISMS OF NANOFILTER FOULING AND TREATMENT ALTERNATIVES FOR SURFACE WATER SUPPLIES.
Creator: Reiss, Charles, Taylor, James, University of Central Florida
Abstract / Description: This dissertation addresses the role of individual fouling mechanisms on productivity decline and solute mass transport in nanofiltration (NF) of surface waters. Fouling mechanisms as well as solute mass transport mechanisms and capabilities must be understood if NF of surface waters is to be successful. Nanofiltration of surface waters was evaluated at pilot-scale in conjunction with advanced pretreatment processes selected for minimization of nanofilter fouling, which constituted several...
Show moreThis dissertation addresses the role of individual fouling mechanisms on productivity decline and solute mass transport in nanofiltration (NF) of surface waters. Fouling mechanisms as well as solute mass transport mechanisms and capabilities must be understood if NF of surface waters is to be successful. Nanofiltration of surface waters was evaluated at pilot-scale in conjunction with advanced pretreatment processes selected for minimization of nanofilter fouling, which constituted several integrated membrane systems (IMSs). Membrane fouling mechanisms of concern were precipitation, adsorption, particle plugging, and attached biological growth. Fouling was addressed by addition of acid and antiscalent for control of precipitation, addition of monochloramine for control of biological growth, microfiltration (MF) or coagulation-sedimentation-filtration (CSF) for control of particle plugging, and in-line coagulation-microfiltration (C/MF) or CSF for control of organic adsorption. Surface water solutes of concern included organic solutes, pathogens, and taste and odor compounds. Solute mass transport was addressed by evaluation of total organic carbon (TOC), Bacillus subtilis endospores, gesomin (G), 2-methlyisoborneol (MIB), and threshold odor number (TON). This evaluation included modeling to determine the role of diffusion in solute mass transport including assessment of the homogeneous solution diffusion equation. A cellulose acetate (CA) NF was less susceptible to fouling than two polyamide (PA) NFs. NF fouling was minimized by the addition of monochloramine, lower flux, lower recovery, and with the use of a coagulant-based pretreatment (C/MF or CSF). NF surface characterization showed that the low fouling CA film was less rough and less negatively charged than the PA films. Thus the theory that a more negatively charged surface would incur less adsorptive fouling, due to charge repulsion, was not observed for these tests. The rougher surface of the PA films may have increased the number of sites for adsorption and offset the charge repulsion benefits of the negatively charged surface. The addition of monochloramine significantly reduced biodegradation and integrity loss of the CA membrane. PA membranes are inherently not biologically degradable due to their chemical structure. Monochloramination reduced the rate of fouling of the PA membrane but resulted in a gradual increase in water mass transfer coefficient and a decrease in TDS rejection over time, which indicated damage and loss of integrity of the PA membrane. Based on surface characterization by X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectrometry (FTIR), the PA membrane degradation appeared to be chemically-based and initiated with chlorination of amide nitrogen and/or aromatic rings, which ultimately resulted in disruption of membrane chemical structures. The recommended Integrated Membrane System to control fouling of a surface water nanofiltration system is CSF monochloramine/acid/antiscalent„³monochloramine-tolerant NF. This IMS, at low flux and recovery, operated with no discernable fouling and is comparable to a groundwater nanofiltration plant with cleaning frequencies of once per six months or longer. A significant portion of the organic solutes including total organic carbon (TOC) passing through the membranes was diffusion controlled. Permeate concentration increased with increasing recovery and with decreasing flux for both PA and CA membranes. The influence was diminished for the PA membrane, due to its high rejection capabilities. Total rejection of spores used as pathogen surrogates was not achieved as spores were indigenous and high spore concentrations were used in all challenge studies; however, Integrated Membrane System spore rejection exceeded credited regulatory rejection of similar sized microorganisms by conventional treatment by several logs. Spore rejection varied by NF but only slightly by MF as size-exclusion controlled. There was no difference among spore rejection of IMS with and without in-line coagulation. Consequently, these results indicate membrane configuration (Hollow fiber>Spiral Wound) and membrane film (Composite Thin Film>CA) significantly affected spore rejection. Geosmin and methylisoborneol have molecular weights of 182 and 168 respectively, and are byproducts of algal blooms, which commonly increase taste and odor as measured by the threshold odor number (TON) in drinking water. Although these molecules are neutral and were thought to pass through NFs, challenge testing of IMS unit operations found that significant removal of TON, G and MIB was achieved by membrane processes, which was far superior to conventional processes. A CA NF consistently removed 35 to 50 percent of TON, MIB, and G, but did not achieve compliance with the TON standard of 3 units. A PA NF provided over 99 percent removal of MIB and G. Challenge tests using MIB and G indicated that size-exclusion controlled mass transfer of these compounds in NF membranes.
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Date Issued: 2005
Identifier: CFE0000630, ucf:46506
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000630

Title: THE EFFECT OF FREE CHLORINE AND CHLORAMINES ON LEAD RELEASE IN A DISTRIBUTION SYSTEM.
Creator: Vasquez, Ferdinand, Taylor, James, University of Central Florida
Abstract / Description: Total lead release in drinking water in the presence of free chlorine and chloramine residuals was investigated in field, laboratory and fundamental investigations for finished waters produced from ground (GW), surface (SW), saline (RO) and blended (B) sources. Field investigations found more total lead was released in the presence of chloramines than in the presence of free chlorine for RO and blended finished waters; however, there were no statistical differences in total lead release to...
Show moreTotal lead release in drinking water in the presence of free chlorine and chloramine residuals was investigated in field, laboratory and fundamental investigations for finished waters produced from ground (GW), surface (SW), saline (RO) and blended (B) sources. Field investigations found more total lead was released in the presence of chloramines than in the presence of free chlorine for RO and blended finished waters; however, there were no statistical differences in total lead release to finished GW and SW. Laboratory measurements of finished waters oxidation-reduction potential (ORP) were equivalent by source and were not affected by the addition of more than 100 mg/L of sulfates or chlorides, but were significantly higher in the presence of free chlorine relative to chloramines. Development of Pourbaix diagrams revealed the PbO2 was the controlling solid phase at the higher ORP in the presence of free chlorine and Pb3(CO3)2(OH)2(s) (hydrocerussite) was the controlling solid phase in the presence of chloramines at the lower ORP, which mechanistically accounted for the observed release of total lead as PbO2 is much less soluble than hydrocerussite. The lack of differences in total lead release to finished GW and SW was attributed to differences in water quality and intermittent behavior of particulate release from controlling solid films.
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Date Issued: 2005
Identifier: CFE0000533, ucf:46427
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000533

Title: NITRIFICATION INVESTIGATION AND MODELING IN THE CHLORAMINATED DRINKING WATER DISTRIBUTION SYSTEM.
Creator: Liu, Suibing, Taylor, James, University of Central Florida
Abstract / Description: This dissertation consists of five papers concerning nitrification in chloraminated drinking water distribution systems in a one and a half year field study. Seven finished waters were produced from different treatment processes and distributed to eighteen pilot distribution systems (PDSs) that were made pipes taken from actual distribution systems. Unlined cast iron (UCI), galvanized steel (G), lined cast iron (LCI), and PVC pipes were used to build the PDSs. All finished waters were...
Show moreThis dissertation consists of five papers concerning nitrification in chloraminated drinking water distribution systems in a one and a half year field study. Seven finished waters were produced from different treatment processes and distributed to eighteen pilot distribution systems (PDSs) that were made pipes taken from actual distribution systems. Unlined cast iron (UCI), galvanized steel (G), lined cast iron (LCI), and PVC pipes were used to build the PDSs. All finished waters were stabilized and chloraminated before entering the PDSs. This dissertation consists of five major parts.(1) System variations of nitrates, nitrites, DO, pH, alkalinity, temperature, chloramine residuals and hydraulic residence times (HRT) during biological nitrification are interrelated and discussed relative to nitrification, which demonstrated Stoichiometric relationships associated with conventional biochemical nitrification reactions. Ammonia is always released when chloramines are used for residual maintenance in drinking water distribution systems, which practically insures the occurrence of biological nitrification to some degree. Biological nitrification was initiated by a loss of chloramine residual brought about by increasing temperatures at a five day HRT, which was accompanied by DO loss and slightly decreased pH. Ammonia increased due to chloramine decomposition and then decreased as nitrification began. Nitrites and nitrates increased initially with time after the chloramine residual was lost but decreased if denitrification began. Dissolved oxygen limited nitrifier growth and nitrification. No significant alkalinity variation was observed during nitrification. Residual and nitrites are key parameters for monitoring nitrification in drinking water distribution systems.(2) Using Monod kinetics, a steady state plug-flow kinetics model was developed to describe the variations of ammonia, nitrite and nitrate-N concentrations in a chloraminated distribution system. Active AOB and NOB biomass in the distribution system was determined using predictive equations within the model. The kinetic model used numerical analysis and was solved by C language to predict ammonia, nitrite, nitrate variation.(3) Nitrification control strategies were investigated during an unexpected episode and controlled study in a field study. Once nitrification began, increasing chloramine dose from 4.0 to 4.5 mg/L as Cl2 and Cl2:N ratio from 4/1 to 5/1 did not stop nitrification. Nitrification was significantly reduced but not stopped, when the distribution system hydraulic retention time was decreased from 5 to 2 days. A free chlorine burn for one week at 5 mg/L Cl2 stopped nitrification. In a controlled nitrification study, nitrification increased with increasing free ammonia and Cl2:N ratios less than 5. Flushing with increased chloramine concentration reduced nitrification, but varying flush frequency from 1 to 2 weeks had no effect on nitrification.(4) HPC variations in a chloraminated drinking water distribution system were investigated. Results showed average residual and temperature were the only water quality variables shown to affect HPC change at a five day distribution system hydraulic residence time was five days. Once nitrification began, HPC change was correlated to HRT, average residual and generated nitrite-N in the distribution system. (5) Biostability was assessed for water treatment processes and distribution system pipe by AOCs, BDOCs, and HPCs of the bulk water, and by PEPAs of the attached biofilms. All membrane finished waters were more likely to be biologically stable as indicated by lower AOCs. RO produced the lowest AOC. The order of biofilm growth by pipe material was UCI > G > LCI > PVC. Biostability decreased as temperature increased.
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Date Issued: 2004
Identifier: CFE0000039, ucf:46151
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000039

Title: IMPACT OF CORROSION INHIBITOR BLENDED ORTHOPHOSPHATE ON WATER QUALITY IN WATER DISTRIBUTION SYSTEMS.
Creator: Alshehri, Abdulrahman, Taylor, James, University of Central Florida
Abstract / Description: The impact of blended orthophosphate (BOP) inhibitor addition on the corrosion of iron, copper, and lead in drinking water distribution systems was studied under changing water quality environment. Release of iron, copper, and lead were monitored at varying inhibitor doses and changing blends of source waters (groundwater, surface water, and desalinated water). Solid corrosion products on pipe surfaces under BOP treatment were evaluated with surface characterization techniques. Performance of...
Show moreThe impact of blended orthophosphate (BOP) inhibitor addition on the corrosion of iron, copper, and lead in drinking water distribution systems was studied under changing water quality environment. Release of iron, copper, and lead were monitored at varying inhibitor doses and changing blends of source waters (groundwater, surface water, and desalinated water). Solid corrosion products on pipe surfaces under BOP treatment were evaluated with surface characterization techniques. Performance of the BOP inhibitor was compared to other corrosion control strategies. Iron scales for iron and galvanized steel coupons incubated in different blended waters in the presence of BOP inhibitor were analyzed by X-ray Photoelectron Spectroscopy (XPS) for surface composition. Identified iron corrosion products were ferric oxide (Fe2O3), magnetite (Fe3O4), and hydrated ferric oxide (FeOOH), in addition to ferric phosphate (FePO4) on coupons exposed to BOP inhibitor. Variations of water quality did not significantly affect the distribution of solid iron forms on surface films. Thermodynamic modeling indicated siderite (FeCO3) was the controlling solid phase of iron release. XPS indicated addition of BOP inhibitor produced a solid phosphate film in the iron scale which could inhibit iron release. Impact of BOP, orthophosphate, and pH adjustment on iron release in a distribution system was examined. Iron release was sensitive to water quality variations (alkalinity and chloride) associated with source and blends of finished water. Finished waters with high alkalinity content (between 149 and 164 mg/L as CaCO3) consistently mitigated iron release regardless of inhibitor use. Dissolved iron constituted about 10% of total iron release. Empirical models were developed that related water quality, inhibitor type and dose to iron release. The BOP inhibitor minimized total iron release followed closely by increasing pH (between 7.9 and 8.1), while orthophosphate dose did not affect iron release. Temperature (ranged from 21.2 to 25.3) had limited influence on iron release with BOP treatment. Monitoring copper release showed that dissolved copper was the dominant form in the effluent, at about 88%. BOP inhibitor doses of 0.5 to 2.0 mg/L proved beneficial in controlling copper concentrations to an average of below 0.5 mg/L. Control of copper release improved with increasing BOP dose, despite changes in alkalinity. Elevation of pH by 0.3 unit beyond pHs (between 7.9 and 8.1) resulted in noticeable decrease in copper concentrations of about 30%, but was more sensitive to higher alkalinity (146 to 151 mg/L as CaCO3) than BOP treatment. Developed empirical models confirmed the importance of BOP inhibitor dose, pH increase, and alkalinity content on copper release. Statistical comparison of the corrosion control strategies proved the advantage of BOP inhibitor, at all doses, over pH elevation in controlling copper release. The BOP inhibitor mitigated lead release below action level, and consistently outperformed pH elevation, in all water quality conditions. XPS analysis identified lead dioxide (PbO2), lead oxide (PbO), cerussite (PbCO3), and hydrocerussite (Pb3(CO3)2(OH)2) as the corrosion products in the scale of lead/tin coupons exposed to BOP inhibitor. XPS and Scanning Electron Microscopy (SEM) analysis suggested cerussite or hydrocerussite is the controlling solid phase of lead release. Thermodynamic models for cerussite and hydrocerussite grossly over predicted actual concentrations. Solubility and equilibrium relationships suggested the possibility of a lead orthophosphate solid that would describe the effectiveness of BOP inhibitor, although no lead-phosphate solid was detected by surface analysis. BOP inhibitor appeared to have mitigated lead release by forming a surface film between lead scale and the bulk water.
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Date Issued: 2008
Identifier: CFE0002229, ucf:47922
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002229

Title: MODELING OF MEMBRANE SOLUTE MASSTRANSFER IN RO/NF MEMBRANE SYSTEMS.
Creator: Zhao, Yu, Taylor, James S., University of Central Florida
Abstract / Description: Five articles describing the impact of surface characteristics, and development of mass transfer models for diffusion controlled membrane applications are published in this dissertation. Article 1 (Chapter 3) describes the impact of membrane surface characteristics and NOM on membrane performance for varying pretreatment and membranes during a field study. Surface charge, hydrophobicity and roughness varied significantly among the four membranes used in the study. Membrane surface...
Show moreFive articles describing the impact of surface characteristics, and development of mass transfer models for diffusion controlled membrane applications are published in this dissertation. Article 1 (Chapter 3) describes the impact of membrane surface characteristics and NOM on membrane performance for varying pretreatment and membranes during a field study. Surface charge, hydrophobicity and roughness varied significantly among the four membranes used in the study. Membrane surface characteristics, NOM and SUVA measurements were used to describe mass transfer in a low pressure RO integrated membrane system. Inorganic and organic solute and water mass transfer coefficients were systematically investigated for dependence on membrane surface properties and NOM mass loading. Inorganic MTCs were accurately described by a Gaussian distribution curve. Water productivity, NOM rejection and inorganic rejection increased as membrane surface charge and NOM loading increased. Inorganic MTCs were also correlated to surface hydrophobicity and surface roughness. The permeability change of identical membranes was related to NOM loading, hydrophobicity and roughness. Organic fouling as measured by water, organic and inorganic mass transfer was less for membranes with higher hydrophilicity and roughness. Article 2 (Chapter 4) describes the development of a diffusion controlled solute mass transfer model to assess membrane performance over time. The changing mass transfer characteristics of four low-pressure reverse osmosis (LPRO) membranes was correlated to feed stream water quality in a 2000 hour pilot study. Solute mass transfer coefficients (MTCs) were correlated to initial solute MTCs, solute charge, feed water temperature, monochloramine loading and organic loading (UV254). The model can be used to predict cleaning frequency, permeate water quality and sensitivity of permeate water quality to variation of temperature, organic and monochloramine mass loading.Article 3 (Chapter 5) describes a comparison of the long standing method of assessing membrane performance (ASTM D 45160 and another approach using mass transfer coefficients (MTCs) from the homogenous solution diffusion model (HSDM) using a common data set, water productivity and standardized salt passage. Both methods were shown to provide identical assessments of water productivity, however different assessments of salt passage. ASTM D 4516 salt passage is normalized for pressure and concentration and does not show the effects of flux, recovery, temperature or specific foulants on salt passage. However the MTC HSDM method is shown to consider all those effects and can be easily used to predict membrane performance at different sites and times of operation, whereas ASTM D 45160 can not. The HSDM MTC method of membrane evaluation is more versatile for assessment of membrane performance at varying sites and changing operational conditions.Article 4 (Chapter 6) describes the development of a fully integrated membrane mass transfer model that considers concentration, recovery and osmotic pressure for prediction of permeate water quality and required feed stream pressures. Osmotic pressure is incorporated into the model using correction coefficients that are calculated from boundary conditions determined from stream osmotic pressures of the feed and concentrate streams. Comparison to homogenous solution diffusion model (HSDM) with and without consideration of osmotic pressure and verification of IOPM using independently developed data from full and pilot scale plants is presented. The numerical simulation and statistical assessment show that osmotic pressure corrected models are superior to none-osmotic pressure corrected models, and that IOPM improves model predictability.Article 5 (Chapter 7) describes the development and comparison of a modified solution diffusion model and two newly developed artificial neural network models to existing mechanistic or empirical model
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Date Issued: 2004
Identifier: CFE0000026, ucf:52859
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000026

Title: THE EFFECTS OF PHOSPHATE AND SILICATE INHIBITORS ON SURFACE ROUGHNESS AND COPPER RELEASE IN WATER DISTRIBUTION SYSTEMS.
Creator: MacNevin, David, Taylor, James, University of Central Florida
Abstract / Description: The effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined...
Show moreThe effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined cast iron, lined cast iron, and polyvinyl chloride was measured using pipe coupons exposed for three months. Roughness of each pipe coupon was measured with an optical surface profiler before and after exposure to inhibitors. For most materials, inhibitor did not have a significant effect on surface roughness; instead, the most significant factor determining the final surface roughness was the initial surface roughness. Coupons with low initial surface roughness tended to have an increase in surface roughness during exposure, and vice versa, implying that surface roughness tended to regress towards an average or equilibrium value. For unlined cast iron, increased alkalinity and increased temperature tended to correspond with increases in surface roughness. Unlined cast iron coupons receiving phosphate inhibitors were more likely to have a significant change in surface roughness, suggesting that phosphate inhibitors affect stability of iron pipe scales. Similar roughness data collected with new copper coupons showed that elevated orthophosphate, alkalinity, and temperature were all factors associated with increased copper surface roughness. The greatest increases in surface roughness were observed with copper coupons receiving phosphate inhibitors. Smaller increases were observed with copper coupons receiving silicate inhibitor or no inhibitor. With phosphate inhibitors, elevated temperature and alkalinity were associated with larger increases in surface roughness and blue-green copper (II) scales.. Otherwise a compact, dull red copper (I) scale was observed. These data suggest that phosphate inhibitor addition corresponds with changes in surface morphology, and surface composition, including the oxidation state of copper solids. The effects of corrosion inhibitors on copper surface chemistry and cuprosolvency were investigated. Most copper scales had X-ray photoelectron spectroscopy binding energies consistent with a mixture of Cu2O, CuO, Cu(OH)2, and other copper (II) salts. Orthophosphate and silica were detected on copper surfaces exposed to each inhibitor. All phosphate and silicate inhibitors reduced copper release relative to the no inhibitor treatments, keeping total copper below the 1.3 mg/L MCLG for all water quality blends. All three kinds of phosphate inhibitors, when added at 1 mg/L as P, corresponded with a 60% reduction in copper release relative to the no inhibitor control. On average, this percent reduction was consistent across varying water quality conditions in all four phases. Similarly when silicate inhibitor was added at 6 mg/L as SiO2, this corresponded with a 25-40% reduction in copper release relative to the no inhibitor control. Hence, on average, for the given inhibitors and doses, phosphate inhibitors provided more predictable control of copper release across changing water quality conditions. A plot of cupric ion concentration versus orthophosphate concentration showed a decrease in copper release consistent with mechanistic control by either cupric phosphate solubility or a diffusion limiting phosphate film. Thermodynamic models were developed to identify feasible controlling solids. For the no inhibitor treatment, Cu(OH)2 provided the closest prediction of copper release. With phosphate inhibitors both Cu(OH)2 and Cu(PO4)·2H2O models provided plausible predictions. Similarly, with silicate inhibitor, the Cu(OH)2 and CuSiO3·H2O models provided plausible predictions.
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Date Issued: 2008
Identifier: CFE0002001, ucf:47621
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002001

Title: THE RELATIONSHIP BETWEEN THE STERLING QUALITY FRAMEWORK AND STUDENT ACHIEVEMENT IN ONE FLORIDA SCHOOL DISTRICT.
Creator: Short, James, Taylor, Rosemarye, University of Central Florida
Abstract / Description: The focus of this research was to determine the relationship, if any, between student achievement and the implementation of the Sterling Quality Management System in a southwest Florida school district. A quantitative analysis focused on three sources of data. Two surveys provided by the Florida Sterling Council were used to collect data from school based personnel and student achievement gain scores obtained from the Florida DOE School Accountability Report 2005-2009. In this study, little...
Show moreThe focus of this research was to determine the relationship, if any, between student achievement and the implementation of the Sterling Quality Management System in a southwest Florida school district. A quantitative analysis focused on three sources of data. Two surveys provided by the Florida Sterling Council were used to collect data from school based personnel and student achievement gain scores obtained from the Florida DOE School Accountability Report 2005-2009. In this study, little positive correlation was found between perceived implementation of Sterling practices and student achievement gains. Of a possible score of 5, the total mean implementation score across all groups was found to be 4.14. This meant that the perceived level of Sterling implementation among respondents overall was very high. No significant correlation was found between the total average Sterling implementation mean score and student achievement gains (school points) made between 2005 and 2009. Overall, very few correlations were found to be statistically significant. This suggested the lack of a linear relationship between Sterling implementation and student achievement gains in the schools in the study Following are recommendations for future research. 1. This study could be repeated using a population of multiple school districts in Florida or in different states. 2. This study could be repeated using different measures of student achievement, such as end of course exam results, SAT or ACT scores, or achievement in Advanced Placement or International Baccalaureate programs in high schools. 3. This study could be repeated with a population of administrators that includes all school principals and assistant principals. 4. This study could be repeated in a school district that has achieved the Sterling Quality award. 5. This study could be repeated to determine a relationship between Sterling Quality and other school effectiveness measures, such as parent involvement, community support, and teacher retention. 6. Determine the relationship if any that the implementation of Sterling Quality practices at the district level has on student achievement.
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Date Issued: 2010
Identifier: CFE0003441, ucf:48416
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003441

Title: Investigating the universality and comprehensive ability of measures to assess the state of workload.
Creator: Abich, Julian, Reinerman, Lauren, Lackey, Stephanie, Szalma, James, Taylor, Grant, University of Central Florida
Abstract / Description: Measures of workload have been developed on the basis of the various definitions, some are designed to capture the multi-dimensional aspects of a unitary resource pool (Kahneman, 1973) while others are developed on the basis of multiple resource theory (Wickens, 2002). Although many theory based workload measures exist, others have often been constructed to serve the purpose of specific experimental tasks. As a result, it is likely that not every workload measure is reliable and valid for all...
Show moreMeasures of workload have been developed on the basis of the various definitions, some are designed to capture the multi-dimensional aspects of a unitary resource pool (Kahneman, 1973) while others are developed on the basis of multiple resource theory (Wickens, 2002). Although many theory based workload measures exist, others have often been constructed to serve the purpose of specific experimental tasks. As a result, it is likely that not every workload measure is reliable and valid for all tasks, much less each domain. To date, no single measure, systematically tested across experimental tasks, domains, and other measures is considered a universal measure of workload. Most researchers would argue that multiple measures from various categories should be applied to a given task to comprehensively assess workload. The goal for Study 1 to establish task load manipulations for two theoretically different tasks that induce distinct levels of workload assessed by both subjective and performance measures was successful. The results of the subjective responses support standardization and validation of the tasks and demands of that task for investigating workload. After investigating the use of subjective and objective measures of workload to identify a universal and comprehensive measure or set of measures, based on Study 2, it can only be concluded that not one or a set of measures exists. Arguably, it is not to say that one will never be conceived and developed, but at this time, one does not reside in the psychometric catalog. Instead, it appears that a more suitable approach is to customize a set of workload measures based on the task. The novel approach of assessing the sensitivity and comprehensive ability of conjointly utilizing subjective, performance, and physiological workload measures for theoretically different tasks within the same domain contributes to the theory by laying the foundation for improving methodology for researching workload. The applicable contribution of this project is a stepping-stone towards developing complex profiles of workload for use in closed-loop systems, such as human-robot team interaction. Identifying the best combination of workload measures enables human factors practitioners, trainers, and task designers to improve methodology and evaluation of system designs, training requirements, and personnel selection.
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Date Issued: 2013
Identifier: CFE0005119, ucf:50675
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005119

Title: An Analysis of High School Homework Guidelines in One Urban School District.
Creator: Larsen, James, Taylor, Rosemarye, Baldwin, Lee, Doherty, Walter, Fritz, Ronald, University of Central Florida
Abstract / Description: The purpose of this study was to evaluate homework guidelines according to criteria identified in the literature. Further the researcher attempted to determine the relationship, if any, between homework guidelines and student achievement results as measured by 2014-2015 high school graduation rates, American College Test (ACT) scores for reading and mathematics, and Scholastic Assessment Test (SAT) scores for reading and mathematics for high schools in one urban school district.A document...
Show moreThe purpose of this study was to evaluate homework guidelines according to criteria identified in the literature. Further the researcher attempted to determine the relationship, if any, between homework guidelines and student achievement results as measured by 2014-2015 high school graduation rates, American College Test (ACT) scores for reading and mathematics, and Scholastic Assessment Test (SAT) scores for reading and mathematics for high schools in one urban school district.A document analysis was conducted focusing on curriculum guides, faculty handbooks, parent handbooks, student handbooks and school websites. Any reference to the identified criteria was recorded in the Homework Criteria Matrix. The next step was to interview the 19 high school principals based on the same criteria. These results were also included in the rubric. An analysis of the data was conducted on the overall presence of elements found for each of the 19 high schools. The elements were quantified and a Pearson r correlation was run to determine the relationship between the presence of homework elements and student achievement results that were being looked at. Data showed that there were few guidelines that were made available to parents and students. The majority of the written homework guidelines were located in the faculty handbook. The other major source of information on homework was the principal interview. Of the sources reviewed, 86% of the homework guidelines that were articulated were found in the faculty handbook and conversations disseminated to the faculty through faculty meetings and Professional Learning Community (PLC) meetings.There were no significant relationships found between homework guidelines and student achievement results as measured by the 2014-2015 high school graduation rates, American College Test (ACT) scores for reading and mathematics, and Scholastic Assessment Test (SAT) scores for reading and mathematics.
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Date Issued: 2016
Identifier: CFE0006342, ucf:51557
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006342

Title: Genetic Engineering as Literary Praxis: A Study in Contemporary Literature.
Creator: Evans, Taylor, Campbell, James, Oliver, Kathleen, Murphy, Patrick, University of Central Florida
Abstract / Description: This thesis considers the understudied issue of genetic engineering as it has been deployed in the literature of the late 20th century. With reference to the concept of the enlightened gender hybridity of Cyborg theory and an eye to ecocritical implications, I read four texts: Joan Slonczewski's 1986 science fiction novel A Door Into Ocean, Octavia Butler's science fiction trilogy Lilith's Brood (-) originally released between 1987 and 1989 as Xenogenesis (-) Simon Mawer's 1997 literary novel...
Show moreThis thesis considers the understudied issue of genetic engineering as it has been deployed in the literature of the late 20th century. With reference to the concept of the enlightened gender hybridity of Cyborg theory and an eye to ecocritical implications, I read four texts: Joan Slonczewski's 1986 science fiction novel A Door Into Ocean, Octavia Butler's science fiction trilogy Lilith's Brood (-) originally released between 1987 and 1989 as Xenogenesis (-) Simon Mawer's 1997 literary novel Mendel's Dwarf, and the first two books in Margaret Atwood's speculative fiction MaddAddam series: 2003's Oryx and Crake and 2009's The Year Of the Flood. I argue that the inclusion of genetic engineering has changed as the technology moves from science fiction to science fact, moving from the fantastic to the mundane. Throughout its recent literary history, genetic engineering has played a role in complicating questions of sexuality, paternity, and the division between nature and culture. It has also come to represent a nexus of potential cultural change, one which stands to fulfill the dramatic hybridity Haraway rhapsodized in her (")Cyborg Manifesto(") while also containing the potential to disrupt the ecocritical conversation by destroying what we used to understand as nature. Despite their four different takes on the issue, each of the texts I read offers a complex vision of utopian hopes and apocalyptic fears. They agree that, for better or for worse, genetic engineering is forever changing both our world and ourselves.
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Date Issued: 2012
Identifier: CFE0004373, ucf:49438
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004373

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