Significance of trihalomethanes in preventing distribution system nitrification

dc.contributor.advisorSpeitel, Gerald E.
dc.creatorBayer, Benjamin Morrey
dc.description.abstractChloramination is popular in drinking water treatment because it can provide microbial control, but unlike chlorination it results in much less formation of disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). Unfortunately, nitrification in drinking water distribution systems is a widespread issue when chloramination is employed as a residual disinfection process. Nitrification is undesirable because the disinfectant residual can be lost and re-growth of bacteria may occur. Nitrification is a well understood process where ammonia-oxidizing bacteria (AOB) oxidize ammonia into nitrite (NO2-), which is then converted to nitrate (NO3-) by nitrite-oxidizing bacteria (NOB). Recent research has shown that AOB are able to biodegrade THMs through an enzymatic process known as cometabolism. The cometabolism by-products are highly reactive substances thought to be capable of either damaging or killing AOB. These observations led to a working hypothesis that under certain conditions and THM concentrations, THMs play a significant role in preventing distribution system nitrification. This research was composed of two distinct tasks aimed at determining how background concentrations of THMs, in the absence of residual disinfectant, impact nitrifying biofilms in a mock distribution system under ideal conditions for microbial growth. For the first task, nitrifying biofilms were developed in annular reactors and were challenged by increasing concentrations of THMs until nitrification was halted. In the next task, THMs were continuously fed to the reactors to determine the concentration of THMs necessary to prevent the initial onset of nitrification. The results from these experiments will be used to design future experiments to investigate the coupled effects of monochloramine and THMs in preventing the onset of nitrification. The goal of this research is to advance our understanding of distribution system nitrification by examining the role that THMs play. This improved understanding will allow utilities to more accurately assess the potential for nitrification in their distribution systems and to anticipate nitrification problems that may arise as a result of treatment process modifications.en_US
dc.description.departmentEnvironmental and Water Resources Engineeringen_US
dc.relation.ispartofUT Electronic Theses and Dissertationsen_US
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en_US
dc.subjectDrinking water treatmenten_US
dc.titleSignificance of trihalomethanes in preventing distribution system nitrificationen_US
dc.type.genreThesisen_US and Water Resources Engineeringen_US and Water Resources Engineeringen_US of Texas at Austinen_US of Scienceen_US

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