The corrosion of the drinking water distribution system is a serious problem in the United States. The annual cost to repair damages related to corrosion for public utilities in the United States are estimated at $22 billion. Polyurethane can be used as an in situ pipe liner which reduces the overall cost to rehabilitate water mains. Polyurethane is gaining popularity as a drinking water pipe liner. Not much is known about the effects of polyurethane to reline potable pipes. Polyurethane has only recently begun to be approved by the U.S. Environmental Protection Agency for use in drinking water piping, although it has been used in the United Kingdom since 1999. The American National Standards Institute/National Sanitation Foundation 61 Drinking Water System Components â Health Effects (ANSI/NSF 61) for pipe and pipe liners was used to investigate changes in water quality in contact with polyurethane lining material. In addition, the exposure time was extended to 30 days and odor analysis was performed. Polyurethane coupons were placed in headspace free borosilicate glass vessels with a surface area to volume ratio of 0.39. The water was pH 8 and comprised of salts: MgSO₄, NaHCO₃, CaSO₄, CaC1₂, Na₂SiO₃ and KNO₃ in a ratio typical of standard drinking water. Three types of disinfectant were used: no disinfectant, chlorine and monochloramine. The water was removed, sampled and replaced on days 1, 2, 4, 9, 11, 14, 15, 19, 21 and 30. The sample water was tested for pH, temperature, total organic carbon concentration (TOC), disinfectant residual, ammonia concentration as N-NH₃, hardness as combined Ca and Mg concentrations, alkalinity and temperature on days when the sample water was changed. Total solids (TS), odor, trihalomethanes (THMs), haloacetic acids (HAAs), and semivolatile organic carbons (SVOCs) were tested on days 1, 4, 9, and 14. The polyurethane lining had major impacts on pH, odor and haloacetic acids throughout the 30 day experiment. A 2-3 pH unit decrease to pH 6 was constant for all conditions tested. Odor panelists described the odor for both chlorinated and monochloraminated waters as "chlorinous" and either pleasant as "sweet chemical" or putrid as "locker room" . Haloacetic acids were formed and increased in concentration (by approximately 30 µg/L, which is half the US EPA regulated value of 60 µg/L). Trihalomethane formation was not seen. Total organic carbon leached from the polyurethane liners reached 0.65 mg/L above background on day 1 but by day 15 was only >0.1 mg/L above background. Chlorine and monochloramine were consumed by the polyurethane and increased exposure time leads to decreased disinfectant residual. It is important for water utilities to know how a lining material will affect the water quality. It has been shown that other polymeric lining materials have impacted the disinfection by-products as well as producing odor. Water treatment facilities are responsible for the water quality throughout the infrastructure and with Environmental Protection Agency regulations becoming stricter they cannot afford to not know the impact of polymeric lining materials in their system. / Master of Science

This document details the results of a study that employed a single element, spiral-wound, thinfilm composite nanofiltration (NF) membrane pilot to assess the treatment effectiveness for aerated and unaerated groundwater supplies. Phase 1 consisted of using raw, unaerated groundwater with standard cartridge filtration (CF) and scale inhibitor (SI) as pretreatment to NF. During the first phase, four water recoveries and crossflow velocities were evaluated to observe how operational conditions affected permeate water quality. Phase 2 involved the simulation of a 70-foot transmission pipeline and sand filter (SF) pilot in series with CF and SI addition pretreatment, prior to NF. Phase 3 employed tray aeration prior to the SF pilot. The pilot was operated for 1,483 run-hours over the three phases, whereupon operational and water quality monitoring ensued to assess NF efficiency. Biological activity tests and foulant analyses were performed to further characterize source water. It was determined statistically that changes in operational conditions in Phase 1 such as crossflow velocity did not significantly affect constituent mass transfer. Phase 2 demonstrated that NF removed total dissolved solids and total organic carbon content greater than 96 percent (%) and 86%, respectively. Phase 3, which exhibited operational difficulties and flux decline, suggested that additional pretreatment is required for NF operation using aerated groundwater. Dimensional analysis (DA) and diffusionbased mass transfer models were employed to predict permeate chloride content for each testing phase; it was determined that the DA overpredicted chloride concentrations by 10 magnitudes and diffusion models were predictive when compared to actual values. The transient response to feed water perturbations within the single-stage membrane process was determined to cause a log-logistic two-and-a-half-minute delay.

No / Drinking water disinfection byproducts (DBPs) are generated by the chemical disinfection of water and may pose a hazard to the public health. Previously we demonstrated that iodoacetic acid was the most cytotoxic and genotoxic DBP analyzed in a mammalian cell system. Little is known of the mechanisms of its genotoxicity. The involvement of oxidative stress in the toxicity of iodoacetic acid was analyzed with the antioxidants catalase and butylated hydroxyanisole (BHA). Iodoacetic acid toxicity was quantitatively measured with and without antioxidants in Salmonella typhimurium strain TA100 and with Chinese hamster ovary (CHO) cells. The endpoints included cytotoxicity in S. typhimurium or in CHO cells, mutagenicity in S. typhimurium, and genotoxicity in CHO cells. Neither catalase nor BHA reduced the level of iodoacetic acid induced cytotoxicity in S. typhimurium. In CHO cells neither antioxidant caused a significant reduction in iodoacetic acid induced cytotoxicity. However, in S. typhimurium, BHA or catalase reduced the mutagenicity of iodoacetic acid by 33.5 and 26.8%, respectively. Likewise, BHA or catalase reduced iodoacetic acid induced genomic DNA damage by 86.5 and 42%, respectively. These results support the hypothesis that oxidative stress is involved in the induction of genotoxicity and mutagenicity by iodoacetic acid.

No / Numerous factors may influence the incidence of diabetes in the population. The production of reactive oxygen species (ROS) is elevated in diabetes patients. Based on the reported involvement of reactive species and nitrate/nitrite in diabetes, this present study has examined in the alkaline Comet assay, the effect of different levels of NaNO2 in the presence of the oxygen radical generating agent, hydrogen peroxide (H2O2). Peripheral lymphocytes from diabetic and non-diabetic Caucasians and Asians of both sexes were studied in vitro. Endogenous factors (e.g., sex, age, body mass index-BMI) and exogenous factors (lifestyle factors e.g., smoking and drinking habits, diet) were taken into account. A preliminary study in two individuals showed that DNA damage remained constant over a wide dose range of NaNO2 (1-75 mM), but when H2O2 was added at a constant concentration of 50 ¿M per dose of NaNO2, there was an increase in DNA damage corresponding with the varying levels of NaNO2 investigated. This was also seen with the 44 individuals (non-diabetic, n = 24; type 1 diabetic, n = 11; type 2 diabetic, n = 9) investigated. NaNO2 was capable of inducing a significant level of DNA damage in lymphocytes (p<0.001), but only with the addition of H2O2. When levels of DNA damage were analysed in terms of the different variables there were few significant differences in damage between diabetic and non-diabetic subjects, or other sub-population groups, and no statistically significant differences in susceptibility were observed between subject covariates using regression techniques.

In this problem, an attempt was made to determine the fate of various species of bacteria which had previously been isolated from other sources when inoculated into Denton tap water.

No description available.

Thesis submitted in fulfillment of the academic requirement for the degree of (M.Tech.: Chemical Engineering), Durban University of Technology, South Africa, Durban, 2015. / Woven Fibre Microfiltration (WFMF) membranes have several advantages over its competitors with respect to durability, making it a favourable alternative for the developing world and operation during rough conditions. Wide application of membrane technology has been limited by membrane fouling. The durability of the WFMF membrane allows more options for flux enhancement and cleaning methods that can be used with the membranes even if they are vigorous. Therefore, the purpose of this work was to develop and evaluate flux enhancement and cleaning strategies for WFMF membranes. Feed samples with high contents of organics and turbidity were required for the study. Based on this, two rivers which are Umkomaasi and Duzi River were identified to satisfy these criteria. A synthetic feed with similar fouling characteristics as the two river water was prepared and used for this study. The synthetic feed solution was made up of 2 g/ℓ of river clay in tap water and 0.5% domestic sewerage was added into the solution accounting for 2% of the total volume. A membrane filtration unit was used for this study. The unit consisted of a pack of five membrane modules which were fully immersed into a 100 litres filtration tank. The system was operated under gravity and the level in the filtration tank was kept constant by a level float. The study focused on evaluating the performance of the woven fibre membrane filtration unit with respect to its fouling propensity to different feed samples. It also evaluated and developed flux enhancement and cleaning strategies and flux restoration after fouling. The results were compared to a base case for flux enhancement and pure water fluxes for cleaning. The WFMF membrane was found to be prone to both internal and external fouling when used in the treatment of raw water (synthetic feed). Internal fouling was found to occur quickly in the first few minutes of filtration and it was the major contributor for the loss of flux from the WFMF membrane. The fouling mechanism responsible for internal fouling was found to be largely pore blocking and pore narrowing due to particle adsorption on/in the membrane pores. The structure (pore size, material and surface layout) of the WFMF membrane was found to be the main cause that made it prone to internal fouling. The IV major fouling of the WFMF membrane was due to internal fouling, a high aeration rate of 30 ℓ/min had minimal effect on the fouling reduction. An aeration rate of 30 ℓ/min improved the average flux by only 36%, where a combination of intermittent backwashing with brushing and intermittent backwashing with aeration (aeration during backwashing only) improved average flux by 187% and 135% respectively. Pre-coating the WFMF membrane with lime reduced the effects of pore plugging and particle adsorption on the membrane and improved the average flux by 66%. The cleaning strategies that were most successful in pure water flux (PWF) recovery were high pressure cleaning and a combination of soaking and brushing the membrane in a 0.1% NaOCl (desired) solution. PWF recovery by these two methods was 97% and 95% respectively. Based on these findings, it was concluded that the WFMF membrane is susceptible to pore plugging by colloidal material and adsorption/attachment by microbiological contaminants which took effect in the first hour of filtration. This led to a 50% loss in flux. Also, a single flux enhancement strategy proved insufficient to maintain a high flux successfully. Therefore, combined flux enhancement strategies yielded the best results.

Submitted in fulfillment of the requirements of the degree of Master of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2016. / River water is a life supporting watercourse to most communities in rural areas. It is used for both human and animal consumption, and is well becoming a collection channel for defecation and urination due to shortage or lack of access to running water and sanitation facilities. This has resulted to the contamination of water sources, which poses a great risk to human health. This has motivated researchers to study simple but yet robust systems to produce safe drinking water. Photocatalysis is one of such emerging disinfection technologies. Titanium dioxide (TiO2) which is one of the basic materials used for paint manufacturing has emerged as an excellent photocatalyst material for water purification. TiO2 was selected in this study because it is locally available with a potential to open a new market in water purification for the manufacturers. The setback in previous studies is the recovery of nano-scaled TiO2 (nTiO2) after purification when used as a suspension in treated water. Thus this study evaluates the performance of four grades of micro-scaled TiO2 (mTiO2) on the degradation of organic matters, Escherichia coli (E. coli) and total coliform in river water and to investigate the percentage recovery of the mTiO2 using a locally manufactured Polyester Woven Fabric Microfiltration (PWFMF) membrane. The PWFMF though uncharacterized has been used in a number of studies for treating domestic and industrial waste waters. The best-performing grade was used to optimize the degradation efficiency of E. coli in river water using the Design of Experiments (DOE) methodology. Grade 2 of the mTiO2, which is hydrated titanium dioxide with additions (ahTiO2) of particle size range of 0.2 – 53 µm at a concentration of 2.5 g/l displayed an advantageous photocatalytic activity. The results show that 80 % of the organics were removed in 3 hours and increased to 93% after 6 hours. Two particle size ranges of 0.2 – 53 µm and 54 – 75 µm at a concentration of 5 g/l degraded organic matters to 90 % and 77 % in 3 hours respectively. The particle size range of 0.2 – 53 µm at a concentration of 5 g/l was then filtered using a PWFMF and turbidities went below 1 NTU after 20 minutes from feed turbidity of 470 NTU for all three trials. The average percentage recovery in 2 hours was 98.91 %. The four grades of mTiO2 were analyzed for E. coli and total coliform for 4 hours at concentrations of 2, 5 and 7 g/l. Grade 2 achieved the E. coli specification of 0 count/ 100 mL at 5 g/l in 2 hours and at 7 g/l in 0.5 hours. Grade 4 E. coli specification was achieved with 7g/l in 4 hours. Grades 2 and 4 performed better since they both achieved the E. coli and total coliform specifications. Grade 2 was the best performing grade and was considered for statistical studies. Grade 2 was then used on a comparative study between the Central Composite Design (CCD) and Box-Behnken Design (BBD), which are two of the major Response Surface Methodologies (RSM). The CCD compared to BBD provides high quality predictions over the entire design space. The CCD obtained optimum results for concentration of mTiO2 (X1), temperature (X2), initial pH (X3) and aeration (X4) which were 6.94 g/l, 28.75 OC, pH = 6.04, and 13.35 L/min for the maximum degradation efficiency of 99.85 % which showed comparable optimum results to the BBD that were 6.45 g/l, 28.28 OC, pH = 6.02 and 12.21 L/min for the maximum degradation efficiency of 99.80%. These theoretical model results were validated by practical experiments that produced the maximum degradation efficiency for CCD and BBD of 99.67 and 99.26 % respectively. Grade 2 of the mTiO2 can be used as a photocatalyst for river water purification due to its strong ability for the removal of E. coli. The additions used in grades 2 and 4 during production improved the photocatalytic activity. The PWFMF membrane showed a great performance of above 98 % particle recovery of mTiO2 from treated water, although there was an indication that the smallest particles were passing through the membrane. The RSM results gave approximately the same optimum results that were well within the limits, which were experimentally validated and showed that the models were sustainable. It is recommended that the effect of additions be studied on the structures or the charge stability of the two grades. / M

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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