Corrosion of iron and copper pipes can produce leaks and loss of efficiency in the water distribution system, elevate levels of contaminants at the tap, and cost billions of dollars annually in pipe replacement or rehabilitation. In situ pipe rehabilitation using cement mortar, polyurethane, and epoxy is a commonly employed method of dealing with aging yet structurally sound pipes because it is less expensive and less invasive than replacing pipe infrastructure. Although epoxy has been shown to be an effective solution to pipe corrosion, little research has been conducted regarding its impact on a comprehensive list of water quality parameters. This research addressed that gap in the literature by conducting short-term immersion tests in which new epoxy linings were exposed to reference tap waters containing one of three disinfectant treatments: no disinfectant, free chlorine, or chloramines. As a comparison, an aged epoxy-lined field sample was also tested. Water exposed to the liners under stagnant conditions was analyzed for the following water quality parameters: pH, ammonia, alkalinity, hardness, metals, disinfectant consumption, total organic carbon (TOC), semi-volatile organic compounds (SVOCs), disinfectant byproduct (DBP) formation, and odor. Results of the study showed relatively low impacts on water quality, as all USEPA drinking water regulations were met. Impacts were highest during the first 24 hour exposure period during which time significant disinfectant consumption was shown (> 90% free chlorine consumed, 13% chloramines consumed), high TOC was leached (2.6-6.2 mg/L), trihalomethanes and haloacetic acids were formed (both < 15 ug/L), Bisphenol-A, an endocrine disrupter, was detected (< 35 ug/L), and odor was reported by panelists at a moderate intensity and described as sweet/chemical/burning/chlorinous. Impacts were much less after the initial 24 hours, although odor remained noticeable throughout the 30 day study. Overall, water quality impacts were greatest in chlorinated waters and both new and aged epoxy showed slight differences in results. / Master of Science

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

In present thesis, the fundamental studies on the reaction between MgO based refractories and slag were undertaken for the development of a carbon-free bonding MgO lining material. Alumina was selected as a potential binder material. Due to MgO-Al2O3 chemical reaction, the developed refractory was bonded by MgO·Al2O3 spinel phase. To begin with, an investigation of the dissolution process of dense MgO and MgO·Al2O3 spinel in liquid slag was carried out. To obtain reliable information for dissolution study, a new experimental method was therefore developed. In this method, a cylinder was rotating centrally in a special designed container with a quatrefoil profile. This method also showed a good reliability in revealing the dissolution mechanism by quenching the whole reaction system. The experimental results showed that the dissolution process of MgO and spinel was controlled by both mass transfer and chemical reaction. It was found that the rapid dissolution of spinel was mainly because of its larger driving force. To improve the resistance against slag penetration, two aspects were studied to develop carbon-free MgO refractory. First, colloidal alumina was used and the effect of its addition into MgO matrix was investigated. The use of colloidal alumina was to form bonding products in the grain boundary of MgO. The results showed that the alumina addition greatly improved the resistance of MgO based refractory against slag penetration in comparison with the decarburized MgO-carbon refractory. It was found that the improvement of resistance was mainly related to the spinel-slag reaction products of CaO·Al2O3 and CaO·MgO·Al2O3 solid phases at the grain boundaries. Second, the effect of particle size distribution on the penetration resistance of MgO was investigated. The most profound improvement against the slag penetration was obtained by using a proper particle size distribution. The results highlighted the importance of considering the refractory structure. Experiments were undertaken to investigate the dissolution mechanism of different types of MgO based refractories in liquid slag. It was observed that the dissolution of spinel bonded MgO refractory was much slower than the decarburized MgO-carbon refractory. The primary dissolution in spinel bonded MgO refractory occurred at the slag-penetrated layer, and the removal of this layer by peeling off enhanced the dissolution rate rapidly. / <p>QC 20170918</p> / European RFCS LEANSTORY project