Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"trihalomethane"”.
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Trihalomethane-forming potential of algal extracellular products and biomass
… be important as precursors in the formation of trihalomethanes during water treatment.
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Trihalomethane formation potential of algal extracellular products and biomass
A study was conducted to determine the importance of algae as sources of orgnanic precursors in the haloform reaction. Two species each of green and blue-green algae were grown in laboratory conditions and harvested periodically during their growth cycle. The principal part of the study was …
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Trihalomethane formation in rural household water filtration systems in Haiti
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.
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Granular activated carbon pretreatment for the removal of trihalomethane precursors
… pretreatment was evaluated for the removal of trihalomethane (THM) precursors from a surface water supply, the Occoquan Reservoir, in northern Virginia. The carbon contactors were operated in the upflow mode at flow rates of 2, 4, and 6 gpm which provided empty bed contact times (EBCT) of 26, …
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Trihalomethane-precursor production by Hydrilla verticillata in the Occoquan Reservoir
This project reviewed the ability of hydrilla to release THM-precursors should this plant become established in the Occoquan Reservoir. It was found that the Occoquan Reservoir could support hydrilla. Three sources of THM-precursors were found to result from hydrilla. These included: 1) …
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The effects of seasonal change, impoundment, and stratification on trihalomethane precursors
… Run, and the stratification of Lake Manassas on trihalomethane (THM)-precursors in Broad Run, upstream and downstream of the reservoir, and in Lake Manassas. An additional objective was to determine the molecular-size distributions of the dissolved organic carbon, and the THM precursors of the …
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Trihalomethane Removal and Re-Formation in Spray Aeration Processes Treating Disinfected Groundwater
… health protection by limiting exposure to four trihalomethanes (THM) and five haloacetic acids (HAA5), formed when chlorine is used for microbial pathogen control. This thesis examines post-aeration TTHM formation when employing spray-aeration processes to remove semi-volatile TTHMs from …
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Oxidation of trihalomethane-precursors and manganese(II) by chlorine dioxide and permanganate
… operation, and the removals of organic carbon, trihalomethane precursors, iron, and manganese. Also, the interaction of the preoxidants with each other when dosed together was investigated. The preoxidant conditions were evaluated on both plant- and laboratory-scale bases. The plant-scale study …
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The removal of specific molecular weight fractions of trihalomethane precursors by alum coagulation
… were evaluated in regards to the removal of trihalomethane (THM) precursors from a surface water supply, Peak Creek, in southwestern Virginia. Water was coagulated with various doses of alum with the pH uncontrolled and with the pH controlled at 5.2 - 5.3. Raw water and treated waters …
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Trihalomethane compounds in the drinking water of Kuwait: A survey from source to consumer
A comprehensive survey of the presence of trihalomethane (THM) compounds, as chlorination by-products, in drinking water in Kuwait have been performed. The survey covers the whole drinking water treatment cycle, starting with sea water and ending with the consumer tap. The data generated by the …
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Evaluation of activated carbon processes for removing trihalomethane precursors from a surface water impoundment
… with and without preoxidation, for reducing trihalomethane [THM] precursor concentrations in Harwood's Mill Reservoir water. Preoxidation with ozone followed by GAC is referred to as the "biological activated carbon" [BAC] process. This study showed that the GAC and BAC processes obtained the …
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The effects of rainfall runoff from urban and rural watersheds on trihalomethane precursors in streams
The purpose of this research was to investigate the relationship between watershed land use and seasonal changes on THM-formation potential from the waters of four streams located in northern Virginia. Specific objectives were to observe the effect of impoundment on downstream THM precursor …
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Process Modeling of Trihalomethanes During Aquifer Storage and Recovery
… periods and recovering water during dry periods. Trihalomethanes are the most common disinfection by-products found in chlorinated water, a result of chlorine reacting with dissolved organic matter, and are linked to adverse human health effects. The study objective is to examine processes …
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The influence of algal growth and related ecological factors in reservoirs on the production and control of trihalomethane precursors
… of organic compounds, especially those that form trihalomethanes upon chlorination and 2) to evaluate the effectiveness of alum coagulation, followed by clarification, for removing THM precursors from lake water. The weekly grab samples provided evidence of a general relationship between algal …
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Assessing Biofiltration without Ozonation for Removal of Trihalomethane Precursors in Drinking Water at the Beaver Water District Drinking Water Treatment Plant
… (DBPs), which include the four regulated trihalomethanes (THMs) and dichloroacetonitrile (DCAN). Rapid small-scale column tests (RSSCTs) and Pilot Plant filters operated at empty-bed contact times (EBCTs) of 4, 8, and 16 minutes were used to evaluate the performance of nutrient-amended …
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Impact of bromide ion concentration, time, dissolved organic carbon and molecular weight cutoff on haloacetonitrile, haloketone, chloropicrin and trihalomethane formation potentials
… haloketones (HKs), chloropicrin (CP) and trihalomethanes (THMs) under conditions of constant DOC, constant Cl:DOC ratio, variable [Br] and variable apparent molecular weight (AMW) for coagulated water from a full-scale water treatment plant. Coagulated, high humic water (4.5 mg DOC/L) was …
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Removal of chlorite by reaction with ferrous iron
… considered when utilities seek to control trihalomethane concentrations. However, concern regarding residual concentrations of chlorite and chlorate have resulted in limitations on applied chlorine dioxide dosages. This study describes the use of ferrous iron as a possible reducing agent …
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Chlorination disinfection by-products in drinking water and risk of pancreatic cancer.
… a lifetime average estimate of known exposure to trihalomethane (THM), bromodichloromethane (BDCM), and chloroform (TCM), while the second provided residence-specific estimates of THM exposure. Adjusted risk estimates were based on the most recent 30 years of exposure with missing data imputed …
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