The formation of disinfection by-products (DBPs) in drinking water has become an issue of greater concern in recent years. Bench-scale jar tests were conducted on a surface water to evaluate the impact of enhanced coagulation on the removal of organic DBP precursors and the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). The results of this testing indicate that enhanced coagulation practices can improve treated water quality without increasing coagulant dosage. The data generated were also used to develop artificial neural networks (ANNs) to predict THM and HAA formation. Testing of these models showed high correlations between the actual and predicted data. In addition, an experimental plan was developed to use ANNs for treatment optimization at the Peterborough pilot plant.

Quantification of natural organic matter (NOM) in water is limited by the complex and varied nature of compounds found in natural waters. Current characterization techniques, which identify and quantify fractions of NOM, are often expensive and time consuming suggesting the need for rapid and accurate characterization methods. In this work, principal component analysis of fluorescence excitation-emission matrices (FEEM-PCA) was investigated as a NOM characterization technique. Through the use of jar tests and disinfection by-product formation tests, FEEM-PCA was shown to be a good surrogate for disinfection by-product precursors. FEEM-PCA was also applied in order to characterize differences in humic-like, protein-like, and Rayleigh scattering between multiple source waters and due to differing treatment processes. A decrease in Rayleigh scattering influence was observed for a deep lake intake, and multiple processes were found to significantly affect humic-like substances, protein-like, and Rayleigh scattering fractions.

N-nitrosamines are considered as a group of emerging disinfection byproducts (DBPs) with potential carcinogenicity at ng/L level. The presence of nitrosamines in drinking water is most commonly associated with chloramination of amine-based precursors. This research investigates the potential of amine-based pharmaceuticals and personal care products (PPCPs) as nitrosamine precursors under practical drinking water disinfection conditions, as well as some critical factors that may affect the nitrosamine formation via PPCPs. All of the twenty selected PPCPs were able to form the corresponding nitrosamines upon chloramine disinfection, and eight of them rendered molar conversions higher than 1 % under practical disinfection conditions. Ranitidine had the highest N-nitrosodimethylamine (NDMA) molar conversion among the tested PPCPs. A three-parameter kinetic model was proposed to describe and predict the NDMA formation from pharmaceuticals during chloramination in various water matrices. The model accurately reflected all three significant characteristics of the NDMA formation curve, including an initial lag phase, followed by a fast increase in NDMA formation, and eventually reaching a plateau. In lab-grade water, the NDMA formation from pharmaceuticals was affected by the Cl2:NH4-N mass ratio, pH, and prechlorination. The NDMA formation increased with the Cl2:NH4-N mass ratio, indicating an enhancement effect of dichloramine. The pH affected both the ultimate NDMA conversion and the reaction rate. The reaction rate is mainly determined by the level of non-protonated amine species, and it increased consistently with increasing pH. The ultimate NDMA conversion is limited by the level of dichloramine, and the maximum NDMA formation occurred in the pH range of 7 to 8. The application of prechlorination may increase or reduce the NDMA conversion, depending on the chlorine reactivity towards the amine group and its surrounding structures. Water matrix components can slow down the initial NDMA formation from selected pharmaceuticals most likely due to the formation of natural organic matter (NOM)-pharmaceutical complexes, while they had less impact on the ultimate NDMA molar conversion. The application of prechlorination may enhance the initial reaction by destroying the NOM-pharmaceutical complexes, but prolonged prechlorination may further inhibit the NDMA formation due to the binding between pharmaceuticals and NOM breakdown products.

The formation of disinfection by-products (DBPs) in drinking water has become an issue of greater concern in recent years. Bench-scale jar tests were conducted on a surface water to evaluate the impact of enhanced coagulation on the removal of organic DBP precursors and the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). The results of this testing indicate that enhanced coagulation practices can improve treated water quality without increasing coagulant dosage. The data generated were also used to develop artificial neural networks (ANNs) to predict THM and HAA formation. Testing of these models showed high correlations between the actual and predicted data. In addition, an experimental plan was developed to use ANNs for treatment optimization at the Peterborough pilot plant.

Quantification of natural organic matter (NOM) in water is limited by the complex and varied nature of compounds found in natural waters. Current characterization techniques, which identify and quantify fractions of NOM, are often expensive and time consuming suggesting the need for rapid and accurate characterization methods. In this work, principal component analysis of fluorescence excitation-emission matrices (FEEM-PCA) was investigated as a NOM characterization technique. Through the use of jar tests and disinfection by-product formation tests, FEEM-PCA was shown to be a good surrogate for disinfection by-product precursors. FEEM-PCA was also applied in order to characterize differences in humic-like, protein-like, and Rayleigh scattering between multiple source waters and due to differing treatment processes. A decrease in Rayleigh scattering influence was observed for a deep lake intake, and multiple processes were found to significantly affect humic-like substances, protein-like, and Rayleigh scattering fractions.

M.Sc. / Natural Organic Matter (NOM) is a complex of organic material present in a natural surface water. Odour, taste and acidity are some of the problems associated with NOM in water systems. Futhermore, it causes the yellow or brown colour of water, whic is aesthetically unpleasant to consumers. NOM is also the energy source of bacterial re-growth and aids in the transportation of metal ions in the distribution system.Moreover, NOM in water can react with disinfectants, e.g. chlorine, to form disinfection by products (DBPs) such as trihalomethanes (THMs) and habacetic acids (HAAs). DBPs have recently been found to have adverse effects in humans. This study was undertaken in order to assess the effectiveness of some of the water treatment techniques employed by selected water supplying companies in dealing with NOM. To achive this, the water treatment processes used by these companies to reduce NOM and metal ions were coagulation, sand filtration, the use of granular activated carbon, ozonation and chlorination. In addition, β-cyclodextrin (β-CD) polyurethanes synthesized in our laboratories were used to remove the DBPs present in the water samples.

Blood trihalomethanes (THMs) and urinary haloacetic acids (HAAs) are the leading candidate biomarkers for disinfection byproduct (DBP) exposure. However, no studies have assessed the exposure profiles, temporal variability, and potential predictors of these biomarkers during pregnancy. Here we collected blood (n = 4304) and urine samples (n = 4165) from 1760 Chinese pregnant women during early, mid-, and late pregnancy, which were separately analyzed for 4 THMs and 2 HAAs. We calculated the intraclass correlation coefficients (ICCs) to assess the variability of these biomarkers and estimated their correlations with sociodemographic, water-use behavioral, dietary and sample collection factors using mixed models. The median concentrations of TCM, BDCM, Br-THMs [sum of BDCM, dibromochloromethane (DBCM), bromoform (TBM)], total THMs (TTHMs, sum of TCM and Br-THMs), DCAA and TCAA in the water distribution system were 4.2 μg/L, 1.7 μg/L, 2.9 μg/L, 7.1 μg/L, 3.4 μg/L and 8.2 μg/L, respectively. Chloroform (TCM), bromodichloromethane (BDCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were detected in > 75% of the biospecimens. Repeated measurements of blood TCM, BDCM, Br-THMs and TTHMs and urinary DCAA and TCAA uniformly exhibited high variability (ICCs = 0.01–0.13); the use of a single measurement to classify gestational average exposure resulted in a high degree of exposure misclassification. The sampling season was a strong predictor of all analyzed DBPs. Additionally, we detected a positive association of blood TCM and BDCM with household income, urinary DCAA with age, and urinary TCAA with tap water usage, education level and amount of tap water consumed. Inverse associations were found between blood BDCM and vegetable consumption, and between blood Br-THM and TTHM and time interval since the last bathing/showering. Afternoon samples had lower DCAA concentrations than did early morning samples. Our results indicate that blood THM and urinary HAA concentrations vary greatly over the course of pregnancy and are affected by sampling season, time of day of blood/urine collection, sociodemographic factors, recent water-use activities and dietary intake.

USEPA regulations of Disinfection By-Products (DBPs) require water suppliers to be in compliance with maximum contaminant levels set by the agency’s Stage 2 DBP Rule. Controlling watershed sources of byproduct precursors are of interest to water suppliers. By-product formation potential and DOC (dissolved organic carbon) character were evaluated at eight sites on four dates (n=32). All sites are within Springfield Water and Sewer Commission’s Cobble Mountain Reservoir watershed (Blandford and Granville, Ma). The goal was to investigate how DBPFP (DBP formation potential) changes in relation to landscape driven changes in DOC chemical characteristics. Analysis was performed on raw water samples using UV-Visible Spectroscopy. 1H Nuclear Magnetic Resonance Spectroscopy (NMR), and Fourier Transform Infrared Spectroscopy (FT-IR) were performed on solid phase extractable (SPE-C18) hydrophobic DOC. Changes in DBPFP are related to landscape changes in hydrophobic DOC characteristics. On three of the four sample dates (n=24) DBPFP was positively correlated to the E2:E3 ratio (R2=.37), SUVA (R2=.72), percent aromatic resonance (R2=.60), and percent carbohydrate resonance (R2=.44). DBPFP on three sample dates (n=24) was negatively correlated to percent aliphatic resonance (R2=.48). DOC aromaticity, SUVA and specific formation potential were lowest in headwater streams and increased with distance downstream. Substantial reductions in DOC concentration are seen upon reservoir export. For most parameters headwater in-stream variability was greater than inter-stream variability. Differences among headwater streams of different forest type are not distinguishable in our small sample size (n=12). Only slight differences in specific formation potential were observed among two different depth samples in Cobble Mountain Reservoir. Our results have implications for watershed management practices in the drinking water supply industry of New England.

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Three oxidants have been evaluated for use as alternative chemical pretreatments for Fena Lake, a surface water that supplies the U.S. Navy's Public Water System (PWS) on the volcanic island of Guam. The study consisted of two investigative components. The first and primary component included a bench-scale evaluation to study the effects of different pre-oxidant chemicals on the formation of chlorinated disinfection by-products (DBPs). The second and ancillary component included a series of water treatment and distribution system management studies that analyzed DBP formation within the treatment plant and water distribution system. The goal of this research was to reduce total trihalomethane (TTHM) and the five haloacetic acid (HAA5) formations in the PWS. In the primary component of the research, raw surface water from Fena Lake was collected by U.S. Navy personnel and shipped to University of Central Florida (UCF) laboratories for experimentation. Bench-scale tests that simulated the coagulation, flocculation, sedimentation and filtration (CSF) that comprises the Navy Water Treatment Plant (NWTP) were used to evaluate the use of two alternative pre-oxidants, potassium permanganate (KMnO4) and chlorine dioxide (ClO2) in lieu of gaseous chlorine (Cl2). The research assessed DBP formation by comparing several pretreatment scenarios, namely: (1) no pretreatment, (2) chlorine pretreatment, and (3) alternative oxidant pretreatment. KMnO4 pretreatment resulted in the lowest percent reduction of TTHMs and HAA5 relative to chlorine pretreatment, at 5.7% and 22.7%, respectively; however, this amount was still a reduction from the results demonstrated for the chlorine pretreatment condition. Without using a pre-oxidant, TTHM and HAA5 formation were reduced by 22.8% and 37.3%, respectively, relative to chlorine pretreatment. Chlorine dioxide demonstrated the greatest TTHM and HAA5 reduction relative to chlorine pretreatment at 34.4% and 53.3%, respectively. The second component of research consisted of a series of studies that evaluated distribution system operations and management alternatives to identify opportunities that could achieve DBP reduction within the PWS. Three concerns that were addressed were the NWTP's compliance with the U.S. Environmental Protection Agency's (USEPA's) Stage 2 Disinfectants/Disinfection By-Products (D/DBP) Rule, variable hydraulic detention times within a small subdivision in the distribution system, and severe weather. It was determined that: (1) A decision based on in-plant studies to cease prechlorination at the NWTP resulted in a decrease in TTHMs and HAA5s throughout the distribution system by 62% and 75%, respectively; (2) A fluoride tracer study led to the discovery of a valved pipeline responsible for elevated DBPs because of excessive water age that when exercised and managed resolved intermittent DBP spikes in the PWS; and (3) when the NWTP's ballasted floc clarifier (BFC) was operated in-series prior to the conventional CSF process during severe weather conditions the TTHM and HAA5 were below 39 ug/L and 29 ug/L, respectively, proving BFC in-series is a practical option for the plant during severe weather.