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- 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.
Show less - Date Issued
- 2004
- Identifier
- CFE0000063, ucf:46118
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000063
- Title
- BIOSTABILITY IN DRINKING WATER DISTRIBUTION SYSTEMS: STUDY AT PILOT-SCALE.
- Creator
-
LE PUIL, Michael, Randall, Andrew A., University of Central Florida
- Abstract / Description
-
Biostability and related issues (e.g. nitrification) were investigated for 18 months in 18 pilot distribution systems, under various water quality scenarios. This study specifically investigated the impact of steady-state water changes on HPC levels in chlorinated and chloraminated distribution systems. Chlorination was more effective than chloramination in reducing HPC levels (1-2 log difference). There was a rapid increase in HPC corresponding to the change in steady-state water quality,...
Show moreBiostability and related issues (e.g. nitrification) were investigated for 18 months in 18 pilot distribution systems, under various water quality scenarios. This study specifically investigated the impact of steady-state water changes on HPC levels in chlorinated and chloraminated distribution systems. Chlorination was more effective than chloramination in reducing HPC levels (1-2 log difference). There was a rapid increase in HPC corresponding to the change in steady-state water quality, which was observed in all PDS. Modeling effort demonstrated that HPC levels reached a maximum within five days after water quality change and return to initial level ten days after the change. Since alkalinity was used as a tracer of the steady-state water quality change, time to reach maximum HPC was related to a mixing model using alkalinity as a surrogate that confirmed alkalinity transition was complete in approximately eight days.Biostability was assessed by HPC levels, since no coliform were ever detected. It was observed that HPC levels would be above four logs if residual droped below 0.1-0.2 mg/L as Cl2, which is below the regulatory minimum of 0.6 mg/L as Cl2. Therefore bacterial proliferation is more likely to be controlled in distribution systems as long as residual regulatory requirements are met. An empirical modeling effort showed that residual, pipe material and temperature were the most important parameters in controlling HPC levels in distribution systems, residual being the only parameter that can be practically used by utilities to control biological stability in their distribution systems. Use of less reactive (i.e. with less chlorine demand) pipes is recommended in order to prevent residual depletion and subsequent bacterial proliferation.This study is investigated biofilm growth simultaneously with suspended growth under a wide range of water quality scenarios and pipe materials. It was found that increasing the degree of treatment led to reduction of biofilm density, except for reverse osmosis treated groundwater, which exerted the highest biofilm density of all waters. Biofilm densities on corrodible, highly reactive materials (e.g. unlined cast iron and galvanized steel) were significantly greater than on PVC and lined cast iron. Biofilm modeling showed that attached bacteria were most affected by temperature and much less by HRT, bulk HPC and residual. The model predicts biofilms will always be active for environments common to drinking water distribution systems. As American utilities do not control biofilms with extensive and costly AOC reduction, American utilities must maintain a strong residual to maintain biological integrity and stability in drinking water distribution systems.Nitrite and nitrate were considered the most suitable indicators for utilities to predict onset of a nitrification episode in the distribution system bulk liquid. DO and ammonia were correlated to production of nitrite and nitrate and therefore could be related to nitrification. However since ammonia and DO consumptions can be caused by other phenomena than nitrification (e.g. oxidation by disinfectant to nitrite and reduction at the pipe wall, respectively), these parameters are not considered indicators of nitrification.Ammonia-Oxidizing Bacteria (AOB) densities in the bulk phase correlated well with nitrite and nitrate production, reinforcing the fact that nitrite and nitrate are good monitoring tools to predict nitrification. Chloramine residual proved to be helpful in reducing nitrification in the bulk phase but has little effect on biofilm densities. As DO has been related to bacterial proliferation and nitrification, it can be a useful and inexpensive option for utilities in predicting biological instability, if monitored in conjunction with residual, nitrite and nitrate. Autotrophic (i.e. AOB) and heterotrophic (i.e. HPC) organisms were correlated in the bulk phase and biofilms.
Show less - Date Issued
- 2004
- Identifier
- CFE0000111, ucf:46183
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000111
- Title
- EVALUATING PROTECTIVE BEHAVIOR STRATEGY INTENTIONS USING THE THEORY OF PLANNED BEHAVIOR.
- Creator
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Sanchez, Dakota, Dvorak, Robert D., University of Central Florida
- Abstract / Description
-
OBJECTIVE: Amongst college students there exists a concerning trend towards problem drinking owed to the cultures on campus that support problem drinking habits. Several interventions are currently used to encourage students to drink wisely with the goal of decreasing this problem drinking and the consequences of these behaviors. The current study analyzes the intention to use Protective Behavior Strategies through the model suggested in the Theory of Planned Behavior (TPB). METHOD: College...
Show moreOBJECTIVE: Amongst college students there exists a concerning trend towards problem drinking owed to the cultures on campus that support problem drinking habits. Several interventions are currently used to encourage students to drink wisely with the goal of decreasing this problem drinking and the consequences of these behaviors. The current study analyzes the intention to use Protective Behavior Strategies through the model suggested in the Theory of Planned Behavior (TPB). METHOD: College student participants (N = 171) completed a web-based survey examining alcohol-related behaviors, intentions, and perceptions at the time of the survey and over the next four weeks. RESULTS AND CONCLUSION: At step 1, PBS intentions was regressed onto age and gender. This accounted for a small amount of variance in intentions. Next, the TPB predictors were added to the model which resulted in a significant improvement in the overall model fit. In the final model, perceived control over PBS use and peer PBS use norms were significant positive predictors of PBS use intentions. Attitudes toward PBS did not predict PBS use intentions.
Show less - Date Issued
- 2019
- Identifier
- CFH2000542, ucf:45640
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000542
- Title
- DEVELOPMENT AND APPLICATION OF MICROELECTRODES TO STUDY IN SITU DISINFECTANT LOSS AND CORROSION ON METAL SURFACE.
- Creator
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Ma, Xiangmeng, Lee, Woo Hyoung, Duranceau, Steven, Sadmani, A H M Anwar, Chumbimuni Torres, Karin, University of Central Florida
- Abstract / Description
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The primary objective of this research was to develop, fabricate, evaluate and utilize microelectrodes to metal coupons in artificial water system. In the brass experiment, it presented profiles of direct measurements of free chlorine/monochloramine, oxygen and pH to brass and cement based coupons. In monochloraminated water, brass showed a much faster corrosion process under observation. Profiles showed a less monochloramine consumption with as high as 7% greater oxygen utilization comparing...
Show moreThe primary objective of this research was to develop, fabricate, evaluate and utilize microelectrodes to metal coupons in artificial water system. In the brass experiment, it presented profiles of direct measurements of free chlorine/monochloramine, oxygen and pH to brass and cement based coupons. In monochloraminated water, brass showed a much faster corrosion process under observation. Profiles showed a less monochloramine consumption with as high as 7% greater oxygen utilization comparing to the brass in free chlorine solution, reflecting oxygen could be a major part of the corrosion initiation process. While cement showed less reactive characteristics to disinfectants and oxygen compared to the brass profiles, however, pH showed a significant rise for cement coupon under monochloramine condition. In galvanic experiment, the developed lead micro-ISE (100 (&)#181;m tip diameter) showed excellent performance toward soluble lead (Pb2+) with the sensitivity of 22.2 (&)#177; 0.5 mV decade-1 and limit of detection (LOD) of 1.22(&)#215;10-6 M (0.25 mg L-1). The response time was less than 10 seconds with a working pH range of 2.0 (-) 7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface over time. Combined with two-dimensional (2D) pH map, this work clearly demonstrated that lead leaching at the metal surface is non-uniform and lower surface pH leads to higher lead leaching from the surface. Once significant pH variation (?pH: 6.0) was developed across brass-lead joint coupon, even a small pH change (?pH: 0.6) within the Pb/Sn alloy resulted in 4 times different surface lead concentrations (42.93 vs. 11.61 mg L-1) and 5 times different fluxes (18.5(&)#215;10-6 vs. 3.5(&)#215;10-6 mg cm-2 s-1). Continuous surface lead leaching monitoring and surface characterization found that free chlorine is the primary contributor to lead leaching.
Show less - Date Issued
- 2017
- Identifier
- CFE0007289, ucf:52165
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007289
- Title
- Using Fluorescence to Characterize Four Day Simulated Distribution System Trihalomethane Content in Florida Groundwaters.
- Creator
-
Ousley, Jonathan, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, University of Central Florida
- Abstract / Description
-
The United States Environmental Protection Agency (USEPA) regulates public water systems and has established limits for certain disinfection by products (DBPs) that have been linked to health effects, such as bladder cancer. The regulation of DBPs, specifically total trihalomethanes (TTHMs) and haloacetic acids (HAAs), have encouraged water treatment professionals to assess the type and amount of organic precursors in their supplies. Three of the more common water quality parameters that are...
Show moreThe United States Environmental Protection Agency (USEPA) regulates public water systems and has established limits for certain disinfection by products (DBPs) that have been linked to health effects, such as bladder cancer. The regulation of DBPs, specifically total trihalomethanes (TTHMs) and haloacetic acids (HAAs), have encouraged water treatment professionals to assess the type and amount of organic precursors in their supplies. Three of the more common water quality parameters that are monitored as DBP surrogates include dissolved organic carbon (DOC), ultraviolet absorbance (UV254), and specific ultraviolet absorbance (SUVA). Although DOC, UV254, and SUVA have been effectively correlated to DBP formation, efforts to correlate fluorescence excitation emission matrices (FEEM) to DBP formation remains limited within the drinking water community. In this research, a fluorescence regional integration (FRI) approach was used to compare FEEM with DOC, UV254, and SUVA as an alternative surrogate for characterizing TTHMs for groundwater sources located in south central Florida. To quantitatively evaluate FEEM, DOC, UV254, and SUVA as TTHM precursor surrogate parameters, a statistical correlation analysis was employed. Thirteen groundwater samples were collected from various Central Florida groundwater wells in Lake County, Polk County, and Palm Beach County, and analyzed for FEEM, DOC, UV254, and SUVA prior to determining the four-day TTHM concentration using a simulated distribution system dosing procedure. The FRI method was then used to quantify FEEM by dividing the three-dimensional matrix into five distinct regions, each representing a unique organic constituent. The volume under each region was determined and used for the correlation analysis.It was determined that a combinations of regions III and V of the FEEM possessed a strong linear correlation to four day TTHM content (R2 = 0.95) as compared to DOC (R2 = 0.906), UV254 (R2= 0.84), SUVA (R2 = 0.640), and the individual regions of the FEEM. However, DOC showed the strongest correlation when a second order polynomial regression was used (R2 = 0.937). Results for the individual regions of the FEEM revealed four day simulated TTHM correlation coefficients of 0.25, 0.62, 0.86, 0.74, and 0.88 for regions I through V respectively. These values indicated that a combination of regions III and V, which represent the fulvic and humic-like organic fractions detected by FEEM respectively, was the most accurate four day simulated TTHM precursor surrogate parameter based on the groundwater supplies tested. These results reveal that although DOC is still one of the strongest surrogate parameters to TTHM formation, fluorescence has also shown to also be a potentially strong surrogate for groundwaters. The implications of these results signify that fluorescence monitoring could be a viable method of measuring organic content in groundwaters once the technology further develops.
Show less - Date Issued
- 2016
- Identifier
- CFE0006839, ucf:51782
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006839
- Title
- Evaluation of Iron and Manganese Control for a Volcanic Surface Water Supply Treated with Conventional Coagulation, Sedimentation and Filtration Processes.
- Creator
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Hall, Christine, Duranceau, Steven, Lee, Woo Hyoung, Randall, Andrew, University of Central Florida
- Abstract / Description
-
A research project assessing the effectiveness of potassium permanganate (KMnO4) for the treatment of iron (Fe) and manganese (Mn) has been conducted by the University of Central Florida (UCF) on behalf of the United States Navy with regards to the water supply on the island of Guam, located in the Marianas Islands. The study consisted of three basic investigative components: one that examined the use of potassium permanganate for iron and manganese control for Fena Lake, a second that...
Show moreA research project assessing the effectiveness of potassium permanganate (KMnO4) for the treatment of iron (Fe) and manganese (Mn) has been conducted by the University of Central Florida (UCF) on behalf of the United States Navy with regards to the water supply on the island of Guam, located in the Marianas Islands. The study consisted of three basic investigative components: one that examined the use of potassium permanganate for iron and manganese control for Fena Lake, a second that examined the existing unit operations that comprised the Navy's water treatment plant (NWTP), and a third that examined iron and manganese field sampling analytical procedures.In the first and primary component of the research, surface water from Fena Lake located within the Naval Magazine in proximity of Santa Rita, Guam was collected at several different lake depths and initially analyzed for iron and manganese using inductively coupled plasma. Subsequent aliquots of Fena Lake collected at the various water depths were transferred to jars then dosed with varying amounts of potassium permanganate after which iron and manganese content was determined. The jars were covered to simulate actual lake to plant transfer conditions experienced at the Navy's on-island facilities. A portion of the jars was dosed with potassium permanganate prior to metals analysis in order to allow for comparisons of baseline conditions. To represent conventional treatment processes, the water samples were then coagulated with aluminum sulfate prior to filtration to remove the oxidized manganese and iron formed from the addition of the potassium permanganate. Coagulated aliquots were filtered and collected to evaluate residual dissolved iron and manganese content. Based on the results of the jar tests it was determined that manganese was reduced by 95% or greater and that iron was completely removed to below the analytical detection limit (0.001 mg/L). It was determined that the potassium permanganate dose required for oxidation of iron was 0.94 mg/mg iron and for manganese was 1.92 mg/mg manganese. It was also observed that when the jars containing aliquots that turned brown in color after potassium permanganate dosing meant that iron and manganese were present and were being oxidized; however, water samples that turned pink were found to be over-dosed with potassium permanganate. The pink water is an undesired characteristic and could result in customer complaints when distributed to the system.The second component of research focused on NWTP existing conditions. Water samples were collected after each key unit operation within the NWTP and analyzed for iron and manganese. This was to determine if pre-chlorination at Fena Lake was effective at removing iron and manganese that could be present in the source water. Analysis was conducted where pre-chlorination at Fena Lake was practiced as well as when no pretreatment was practiced prior to the NWTP. It was determined that the iron and manganese were not detected downstream of the coagulation unit operation within the NWTP even when pre-chlorination was not practiced. Consequently pre-chlorination of Fena Lake source water was not required for controlling iron and manganese under the conditions experienced in this study.A third study was also implemented to confirm that 0.1-micron filters are appropriate for use in preparing samples for analytical determination of iron and manganese analysis at various points within the NWTP. The filtration step is important to delineate between dissolved and suspended iron and manganese forms. Standard Methods 3120B recommends the use of 0.45-micron filters, although based on literature it has been shown that oxidized manganese particles may be smaller than a 0.45-micron pore size. Unless a coagulant was used, the oxidized manganese may not be fully removed via the 0.45-micron filter. To verify the effectiveness of using a 0.1-micron filter, a jar test was conducted to compare the use of a 0.1-micron filter, a 0.45-micron filter, and a 0.45-micron filter after the sample has been coagulated. It was found that the use of a 0.1-micron filter was superior to the use of 0.45-micron filters even with coagulant addition when directly comparing between dissolved and suspended iron and manganese forms. It is recommended that 0.1-microns be utilized in lieu of historically recommended 0.45-micron filters for sample preparation procedures.
Show less - Date Issued
- 2014
- Identifier
- CFE0005180, ucf:50655
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005180
- 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.
Show less - Date Issued
- 2007
- Identifier
- CFE0001931, ucf:47453
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001931
- Title
- SODIUM (NA) LEVELS IN DRINKING WATER (H20) AND DEVELOPMENT OF HYPERTENSION IN CHILDREN.
- Creator
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Schiffman, Sara, Bushy, Angeline, University of Central Florida
- Abstract / Description
-
This integrative review of the literature focused on sodium (Na) content in drinking water (H2O) supplies and the subsequent effect on blood pressure levels in children. Studies for this review were drawn from the Cumulative Index of Nursing and Allied Health, PubMED, Science and Technology Databases, PsychInfo, United States (US) Environmental Protection Agency (EPA) and EPA in Florida websites. Criterion for inclusion in the data base searches were hypertension, high blood pressure, sodium...
Show moreThis integrative review of the literature focused on sodium (Na) content in drinking water (H2O) supplies and the subsequent effect on blood pressure levels in children. Studies for this review were drawn from the Cumulative Index of Nursing and Allied Health, PubMED, Science and Technology Databases, PsychInfo, United States (US) Environmental Protection Agency (EPA) and EPA in Florida websites. Criterion for inclusion in the data base searches were hypertension, high blood pressure, sodium in drinking water, drinking water salinity, children or preg*. Subsequently, further article selection criteria included children (under 18 years of age)and published in the English language (N=59). Findings of the review as summarized in this thesis could guide nursing research, education, policy and practice related to primary, secondary and tertiary interventions associated with sodium levels in drinking as a contributing factor to blood pressure levels in children.
Show less - Date Issued
- 2013
- Identifier
- CFH0004469, ucf:45123
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004469
- Title
- BIOSTABILITY IN DRINKING WATER DISTRIBUTION SYSTEMS IN A CHANGING WATER QUALITY ENVIRONMENT USING CORROSION INHIBITORS.
- Creator
-
Zhao, Bingjie, Randall, Andrew, University of Central Florida
- Abstract / Description
-
In this study, the bacterial growth dynamics of 14 pilot drinking water distribution systems were studied in order to observe water quality changes due to corrosion inhibitor addition. Empirical models were developed to quantity the effect of inhibitor type and dose on bacterial growth (biofilm and bulk water). Water and pipe coupon samples were taken and examined during the experiments. The coupons were exposed to drinking water at approximately 20 °C for at least 5 weeks to allow the...
Show moreIn this study, the bacterial growth dynamics of 14 pilot drinking water distribution systems were studied in order to observe water quality changes due to corrosion inhibitor addition. Empirical models were developed to quantity the effect of inhibitor type and dose on bacterial growth (biofilm and bulk water). Water and pipe coupon samples were taken and examined during the experiments. The coupons were exposed to drinking water at approximately 20 °C for at least 5 weeks to allow the formation of a measurable quasi- steady-state biofilm. Bulk water samples were taken every week. In this study, two simple but practical empirical models were created. Sensitivity analysis for the bulk HPC model (for all 14 of the PDSs) showed that maintaining a chloramine residual at 2.6 mg/L instead of 1.1 mg/L would decrease bulk HPC by anywhere from 0.5 to 0.9 log, which was greater than the increase in bulk HPC from inhibitor addition at 0.31 to 0.42 log for Si and P based inhibitors respectively. This means that maintaining higher residual levels can counteract the relatively modest increases due to inhibitors. BF HPC was affected by pipe material, effluent residual and temperature in addition to a small increase due to inhibitor addition. Biofilm density was most affected by material type, with polyvinyl chloride (PVC) biofilm density consistently much lower than other materials (0.66, 0.92, and 1.22 log lower than lined cast iron (LCI), unlined cast iron (UCI), and galvanized steel (G), respectively). Temperature had a significant effect on both biofilm and bulk HPC levels but it is not practical to alter temperature for public drinking water distribution systems so temperature is not a management tool like residual. This study evaluated the effects of four different corrosion inhibitors (i.e. based on either phosphate or silica) on drinking water distribution system biofilms and bulk water HPC levels. Four different pipe materials were used in the pilot scale experiments, polyvinyl chloride (PVC), lined cast iron (LCI), unlined cast iron (UCI), and galvanized steel (G). Three kinds of phosphate based and one silica based corrosion inhibitors were added at concentrations typically applied in a drinking water distribution system for corrosion control. The data showed that there was a statistically significant increase of 0.34 log in biofilm bacterial densities (measured as HPC) with the addition of any of the phosphate based inhibitors (ortho-phosphorus, blended ortho-poly-phosphate, and zinc ortho-phosphate). A silica based inhibitor resulted in an increase of 0.36 log. The biological data also showed that there was a statistically significant increase in bulk water bacterial densities (measured as heterotrophic plates count, HPC) with the addition of any of the four inhibitors. For bulk HPC this increase was relatively small, being 15.4% (0.42 log) when using phosphate based inhibitors, and 11.0% (0.31 log) for the silica based inhibitor. Experiments with PDS influent spiked with phosphate salts, phosphate based inhibitors, and the silicate inhibitor showed that the growth response of P17 and NOx in the AOC test was increased by addition of these inorganic compounds. For this source water and the PDSs there was more than one limiting nutrient. In addition to organic compounds phosphorus was identified as a nutrient stimulating growth, and there was also an unidentified nutrient in the silica based inhibitor. However since the percentage increases due to inhibitors were no greater than 15% it is unlikely that this change would be significant for the bulk water microbial quality. In addition it was shown that increasing the chloramines residual could offset any additional growth and that the inhibitors could help compliance with the lead and copper rule. However corrosion inhibitors might result in an increase in monitoring and maintenance requirements, particularly in dead ends, reaches with long HRTs, and possibly storage facilities. In addition it is unknown what the effect of corrosion inhibitors are on the growth of coliform bacteria and opportunistic pathogens relative to ordinary heterotrophs. A method was developed to monitor precision for heterotrophic plate count (HPC) using both blind duplicates and lab replicates as part of a project looking at pilot drinking water distribution systems. Precision control charts were used to monitor for changes in assay variability with time just as they are used for chemical assays. In adapting these control charts for the HPC assay, it was determined that only plate counts ≥ 30 cfu per plate could be used for Quality Assurance (QA) purposes. In addition, four dilutions were used for all known Quality Control (QC) samples to insure counts usable for QC purposes would be obtained. As a result there was a 50% increase in the required labor for a given number of samples when blind duplicates and lab replicates were run in parallel with the samples. For bulk water HPCs the distributions of the duplicate and replicate data were found to be significantly different and separate control charts were used. A probability based analysis for setting up the warning limit (WL) and control limit (CL) was compared with the method following National Institute of Standard and Technology (NIST) guidelines.
Show less - Date Issued
- 2007
- Identifier
- CFE0001947, ucf:47452
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001947
- 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.
Show less - Date Issued
- 2007
- Identifier
- CFE0001953, ucf:47430
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001953
- 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.
Show less - Date Issued
- 2004
- Identifier
- CFE0000039, ucf:46151
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000039
- Title
- DECREASING ALCOHOL USE AMONG HIGH SCHOOL STUDENTS BY CHALLENGING ALCOHOL EXPECTANCIES.
- Creator
-
Cruz, Iris, Dunn, Michael, University of Central Florida
- Abstract / Description
-
Altering alcohol expectancies has reduced alcohol use among college students and may lead to successful prevention of alcohol use among high school students. We randomly assigned 379 12th-grade students to an expectancy challenge, traditional alcohol information, or control condition, and used Individual Differences Scaling to map expectancies into memory network format with Preference Mapping to model likely paths of association. After expectancy and traditional alcohol interventions, higher...
Show moreAltering alcohol expectancies has reduced alcohol use among college students and may lead to successful prevention of alcohol use among high school students. We randomly assigned 379 12th-grade students to an expectancy challenge, traditional alcohol information, or control condition, and used Individual Differences Scaling to map expectancies into memory network format with Preference Mapping to model likely paths of association. After expectancy and traditional alcohol interventions, higher drinking male participants exhibited a greater likelihood to associate alcohol use with negative and sedating consequences and a decreased likelihood to associate alcohol with positive and arousing consequences. Drinking decreases paralleled the magnitude of changes in their likely path of expectancy activation. Children and adults who emphasize negative and sedating effects have been found to be less likely to use alcohol. Therefore, expectancy challenge interventions that have been successful at modifying expectancies and subsequently decreasing alcohol consumption among heavy drinking college students may be useful in the development of prevention curricula for high school students.
Show less - Date Issued
- 2006
- Identifier
- CFE0001232, ucf:46887
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001232
- Title
- Stand-Alone Personalized Normative Feedback for College Student Drinkers: A Meta-Analytic Review, 2004 to 2014.
- Creator
-
Dotson, Keri, Dunn, Michael, Cassisi, Jeffrey, Bowers, Clint, University of Central Florida
- Abstract / Description
-
Personalized normative feedback (PNF) has shown promise as a stand-alone intervention for reducing alcohol use among college students. PNF uses norms clarification to correct drinking norms misperceptions by highlighting discrepancies between personal alcohol use, perceived peer alcohol use, and actual peer alcohol use. Previous reviews of personalized feedback interventions have identified norms clarification as key a component, prompting researchers to study PNF as a single-component...
Show morePersonalized normative feedback (PNF) has shown promise as a stand-alone intervention for reducing alcohol use among college students. PNF uses norms clarification to correct drinking norms misperceptions by highlighting discrepancies between personal alcohol use, perceived peer alcohol use, and actual peer alcohol use. Previous reviews of personalized feedback interventions have identified norms clarification as key a component, prompting researchers to study PNF as a single-component intervention for college drinking. As the number of publications focused on PNF effectiveness has increased in recent years, an empirical review of these studies is warranted to assess the potential impact of PNF as a stand-alone program. The purpose of the present study was to summarize available research and to perform a meta-analytic review of personalized normative feedback as a stand-alone intervention for college student drinking. Studies were included if they examined a stand-alone PNF drinking intervention, used a college student sample, reported alcohol use outcomes, and used a pre-post experimental design with follow-up at least 28 days post-intervention. Eight studies (13 interventions) completed between 2004 and 2014 were included. Effect size estimates (ESs) were calculated as the standardized mean difference in change scores between treatment and control groups. Compared to control participants, students who received PNF reported a greater reduction in drinking and harms from baseline to follow-up. Results were similar for both gender-neutral and gender-specific PNF. Overall, intervention effects for drinking were small but reliable. This study offers an empirical summary of stand-alone PNF for reducing college student drinking and provides a foundation for future research.
Show less - Date Issued
- 2015
- Identifier
- CFE0005606, ucf:50257
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005606
- Title
- In-Plant and Distribution System Corrosion Control for Reverse Osmosis, Nanofiltration, and Anion Exchange Process Blends.
- Creator
-
Jeffery, Samantha, Duranceau, Steven, Randall, Andrew, Wang, Dingbao, University of Central Florida
- Abstract / Description
-
The integration of advanced technologies into existing water treatment facilities (WTFs) can improve and enhance water quality; however, these same modifications or improvements may adversely affect finished water provided to the consumer by public water systems (PWSs) that embrace these advanced technologies. Process modification or improvements may unintentionally impact compliance with the provisions of the United States Environmental Protection Agency's (USEPA's) Safe Drinking Water Act ...
Show moreThe integration of advanced technologies into existing water treatment facilities (WTFs) can improve and enhance water quality; however, these same modifications or improvements may adversely affect finished water provided to the consumer by public water systems (PWSs) that embrace these advanced technologies. Process modification or improvements may unintentionally impact compliance with the provisions of the United States Environmental Protection Agency's (USEPA's) Safe Drinking Water Act (SDWA). This is especially true with respect to corrosion control, since minor changes in water quality can affect metal release. Changes in metal release can have a direct impact on a water purveyor's compliance with the SDWA's Lead and Copper Rule (LCR). In 2010, the Town of Jupiter (Town) decommissioned its ageing lime softening (LS) plant and integrated a nanofiltration (NF) plant into their WTF. The removal of the LS process subsequently decreased the pH in the existing reverse osmosis (RO) clearwell, leaving only RO permeate and anion exchange (AX) effluent to blend. The Town believed that the RO-AX blend was corrosive in nature and that blending with NF permeate would alleviate their concern. Consequently, a portion of the NF permeate stream was to be split between the existing RO-AX clearwell and a newly constructed NF primary clearwell. The Town requested that the University of Central Florida (UCF) conduct research evaluating how to mitigate negative impacts that may result from changing water quality, should the Town place its AX into ready-reserve. The research presented in this document was focused on the evaluation of corrosion control alternatives for the Town, and was segmented into two major components: 1.The first component of the research studied internal corrosion within the existing RO clearwell and appurtenances of the Town's WTF, should the Town place the AX process on standby. Research related to WTF in-plant corrosion control focused on blending NF and RO permeate, forming a new intermediate blend, and pH-adjusting the resulting mixture to reduce corrosion in the RO clearwell. 2.The second component was implemented with respect to the Town's potable water distribution system. The distribution system corrosion control research evaluated various phosphate-based corrosion inhibitors to determine their effectiveness in reducing mild steel, lead and copper release in order to maintain the Town's continual compliance with the LCR.The primary objective of the in-plant corrosion control research was to determine the appropriate ratio of RO to NF permeate and the pH necessary to reduce corrosion in the RO clearwell. In this research, the Langelier saturation index (LSI) was the corrosion index used to evaluate the stability of RO:NF blends. Results indicated that a pH-adjusted blend consisting of 70% RO and 30% NF permeate at 8.8-8.9 pH units would produce an LSI of +0.1, theoretically protecting the RO clearwell from corrosion.The primary objective of the distribution system corrosion control component of the research was to identify a corrosion control inhibitor that would further reduce lead and copper metal release observed in the Town's distribution system to below their respective action limits (ALs) as defined in the LCR. Six alternative inhibitors composed of various orthophosphate and polyphosphate (ortho:poly) ratios were evaluated sequentially using a corrosion control test apparatus. The apparatus was designed to house mild steel, lead and copper coupons used for weight loss analysis, as well as mild steel, lead solder and copper electrodes used for linear polarization analysis. One side of the apparatus, referred to as the (")control condition,(") was fed potable water that did not contain the corrosion inhibitor, while the other side of the corrosion apparatus, termed the (")test condition,(") was fed potable water that had been dosed with a corrosion inhibitor. Corrosion rate measurements were taken twice per weekday, and water quality was measured twice per week. Inhibitor evaluations were conducted over a span of 55 to 56 days, varying with each inhibitor. Coupons and electrodes were pre-corroded to simulate existing distribution system conditions. Water flow to the apparatus was controlled with an on/off timer to represent variations in the system and homes. Inhibitor comparisons were made based on their effectiveness at reducing lead and copper release after chemical addition. Based on the results obtained from the assessment of corrosion inhibitors for distribution system corrosion control, it appears that Inhibitors 1 and 3 were more successful in reducing lead corrosion rates, and each of these inhibitors reduced copper corrosion rates. Also, it is recommended that consideration be given to use of a redundant single-loop duplicate test apparatus in lieu of a double rack corrosion control test apparatus in experiments where pre-corrosion phases are implemented. This recommendation is offered because statistically, the control versus test double loop may not provide relevance in data analysis. The use of the Wilcoxon signed ranks test comparing the initial pre-corroding phase to the inhibitor effectiveness phase has proven to be a more useful analytical method for corrosion studies.
Show less - Date Issued
- 2013
- Identifier
- CFE0005008, ucf:50001
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005008
- Title
- "Have a smile with me?".
- Identifier
- DP0015465
- Format
- Set of related objects
- PURL
- http://purl.flvc.org/ucf/fd/DP0015465
- 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.
Show less - Date Issued
- 2005
- Identifier
- CFE0000533, ucf:46427
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000533
- Title
- EFFECTS OF CAFFEINATED ENERGY DRINK AND ALCOHOL USAGE ON PERCEIVED STRESS AND BURNOUT IN UNDERGRADUATE STUDENTS.
- Creator
-
Patel, Arjun, Webster, Danielle, University of Central Florida
- Abstract / Description
-
Caffeinated energy beverages (CEDs) are a growing supplement being consumed by a large number of young adults aged 18 to 24 years of age. As these CEDs contain nutritional supplements, they are not classified the same way other beverages such as sodas are and they can thus bypass regulation by the Food and Drug Administration. Without regulation by this governing body, it is important to understand how these supplements may be affecting their target population. In this study, students from a...
Show moreCaffeinated energy beverages (CEDs) are a growing supplement being consumed by a large number of young adults aged 18 to 24 years of age. As these CEDs contain nutritional supplements, they are not classified the same way other beverages such as sodas are and they can thus bypass regulation by the Food and Drug Administration. Without regulation by this governing body, it is important to understand how these supplements may be affecting their target population. In this study, students from a large university were recruited in order to determine patterns of CED usage as well as how CED usage may affect perceived stress and burnout. Alcohol usage, another type of beverage commonly consumed in this population, was also assayed in this group in order to determine how perceived stress and burnout are affected. The study was case-control in nature, as regular users of CEDs were compared against students who were not regular consumers. From the data, no major relationships could be identified in regards to perceived stress, burnout, and CED usage. However, extracurricular activity was found to be somewhat predictive of CED usage while alcohol usage was found to be negatively correlated with perceived stress.
Show less - Date Issued
- 2015
- Identifier
- CFH0004787, ucf:45333
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004787
- 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.
Show less - Date Issued
- 2008
- Identifier
- CFE0002229, ucf:47922
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002229
- Title
- IMPLEMENTATION AND EVALUATION OF A CLASSROOM-BASED APPROACH TO EXPECTANCY CHALLENGE FOR REDUCING ALCOHOL USE AMONG FIRST-YEAR COLLEGE STUDENTS.
- Creator
-
Sivasithamparam, Janani, Dunn, Michael, University of Central Florida
- Abstract / Description
-
There is a pervasive belief in the United States that the college experience typically includes frequent social activities characterized by widespread alcohol use. Unfortunately, awareness of the hundreds of deaths and wide variety of other harms experienced by college students as a result of alcohol use is much less pervasive. In an effort to increase awareness of the negative impact of alcohol use on college campuses, the NIAAA commissioned a panel composed of scientists and college...
Show moreThere is a pervasive belief in the United States that the college experience typically includes frequent social activities characterized by widespread alcohol use. Unfortunately, awareness of the hundreds of deaths and wide variety of other harms experienced by college students as a result of alcohol use is much less pervasive. In an effort to increase awareness of the negative impact of alcohol use on college campuses, the NIAAA commissioned a panel composed of scientists and college presidents to document alcohol-related harms and identify strategies that have been found to be effective in reducing risky alcohol use based on empirical evidence. The final report of this expert panel was released as a "Call to Action" for institutions nationwide in an effort to increase understanding of the severity and prevalence of risky alcohol use, and to provide descriptions of programs that were considered effective based on empirical evidence. Unfortunately, there were very few strategies found to be effective, and one of the effective approaches could only be implemented in specialized laboratories operated by scientists with expertise in expectancy challenge. Due to the severity and pervasiveness of the college alcohol problem and the limited number of strategies deemed effective, there is clearly a pressing need to develop and validate an expectancy challenge method that could be implemented by any institution without being limited by the need for a specialized laboratory and highly trained personnel. Achievement of these goals was the focus of the present project. To this end, an expectancy challenge curriculum designed for delivery in a college classroom was developed based on a laboratory delivered protocol previously found to be effective in reducing alcohol use among college students, and a classroom delivered curriculum previously found to be effective with high school students. The newly developed college classroom curriculum was implemented in a single session with groups of students during their regular class time in their usual classroom. Measures of alcohol use and associated harms were completed anonymously by each participant before completing the curriculum and for the month following completion of the curriculum. Analyses indicated significant reductions in alcohol consumption among males and females in comparison to students who were randomly assigned to a wait-list control condition. Unfortunately, significant reductions in alcohol-related harms were not found. The time periods for baseline and follow-up were only one month each, and that limitation in the number of opportunities to experience harms limits the likelihood of demonstrating a significant reduction in harms as well. Overall, this project represents an important advance in the development of alcohol use reduction strategies that are theory-based and effective in reducing alcohol use based on empirical evidence. In addition, the curriculum that was developed and validated in this project represents the first expectancy challenge method that can be readily implemented at any institution willing to devote one hour to reducing their students' risk for a long list of negative consequences associated with alcohol use on college campuses. Motivation and a typical classroom are all that is needed.
Show less - Date Issued
- 2008
- Identifier
- CFE0002307, ucf:47854
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002307
- Title
- EFFECTS OF ORTHOPHOSPHATE CORROSION INHIBITOR IN BLENDED WATER QUALITY ENVIRONMENTS.
- Creator
-
Stone, Erica, Duranceau, Steven, University of Central Florida
- Abstract / Description
-
This study evaluated the effects of orthophosphate (OP) inhibitor addition on iron, copper, and lead corrosion on coupons exposed to different blends of groundwater, surface water, and desalinated seawater. The effectiveness of OP inhibitor addition on iron, copper, and lead release was analyzed by statistical comparison between OP treated and untreated pilot distribution systems (PDS). Four different doses of OP inhibitor, ranging from zero (control) to 2 mg/L as P, were investigated and non...
Show moreThis study evaluated the effects of orthophosphate (OP) inhibitor addition on iron, copper, and lead corrosion on coupons exposed to different blends of groundwater, surface water, and desalinated seawater. The effectiveness of OP inhibitor addition on iron, copper, and lead release was analyzed by statistical comparison between OP treated and untreated pilot distribution systems (PDS). Four different doses of OP inhibitor, ranging from zero (control) to 2 mg/L as P, were investigated and non-linear empirical models were developed to predict iron, copper, and lead release from the water quality and OP doses. Surface characterization evaluations were conducted using X-ray Photoelectron Spectroscopy (XPS) analyses for each iron, galvanized steel, copper, and lead/tin coupon tested. Also, a theoretical thermodynamic model was developed and used to validate the controlling solid phases determined by XPS. A comparison of the effects of phosphate-based corrosion inhibitor addition on iron, copper, and lead release from the PDSs exposed to the different blends was also conducted. Three phosphate-based corrosion inhibitors were employed; blended orthophosphate (BOP), orthophosphate (OP), and zinc orthophosphate (ZOP). Non-linear empirical models were developed to predict iron, copper, and lead release from each PDS treated with different doses of inhibitor ranging from zero (control) to 2 mg/L as P. The predictive models were developed using water quality parameters as well as the inhibitor dose. Using these empirical models, simulation of the water quality of different blends with varying alkalinity and pH were used to compare the inhibitors performance for remaining in compliance for iron, copper and lead release. OP inhibitor addition was found to offer limited improvement of iron release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increased total phosphorus, pH, and alkalinity reduced iron release while increased silica, chloride, sulfate, and temperature contributed to iron release. Thermodynamic modeling suggested that FePO4 is the controlling solid that forms on iron and galvanized steel surfaces, regardless of blend, when OP inhibitor is added for corrosion control. While FePO4 does not offer much control of the iron release from the cast iron surfaces, it does offer protection of the galvanized steel surfaces reducing zinc release. OP inhibitor addition was found to reduce copper release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increases in total phosphorus, silica, and pH reduced copper release while increased alkalinity and chloride contributed to copper release. Thermodynamic modeling suggested that Cu3(PO4)2•2H2O is the controlling solid that forms on copper surfaces, regardless of blend, when OP inhibitor is added for corrosion control. OP inhibitor addition was found to reduce lead release for the OP dosages evaluated for the water blends evaluated compared to pH adjustment alone. Empirical models showed increased total phosphorus and pH reduced lead release while increased alkalinity, chloride, and temperature contributed to lead release. Thermodynamic modeling suggested that hydroxypyromorphite is the controlling solid that forms on lead surfaces, regardless of blend, when OP inhibitor is added for corrosion control. The comparison of phosphate-based inhibitors found increasing pH to reduce iron, copper, and lead metal release, while increasing alkalinity was shown to reduce iron release but increase copper and lead release. The ZOP inhibitor was not predicted by the empirical models to perform as well as BOP and OP at the low dose of 0.5 mg/L as P for iron control, and the OP inhibitor was not predicted to perform as well as BOP and ZOP at the low dose of 0.5 mg/L as P for lead control. The three inhibitors evaluated performed similarly for copper control. Therefore, BOP inhibitor showed the lowest metal release at the low dose of 0.5 mg/L as P for control of iron, copper, and lead corrosion.
Show less - Date Issued
- 2008
- Identifier
- CFE0002382, ucf:47760
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002382
