Modeling trihalomethane formation in drinking water after alum coagulation or activated carbon adsorption

Persistent Link:
http://hdl.handle.net/10150/191095
Title:
Modeling trihalomethane formation in drinking water after alum coagulation or activated carbon adsorption
Author:
Chadik, Paul Arthur
Issue Date:
1985
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Eight natural waters from throughout the United States were subjected to different degrees of alum coagulation and activated carbon adsorption treatment (not in series). The concentration of trihalomethanes (THMs) formed by the reaction between the natural aquatic organics and doses of free chlorine were determined by gas chromatography at ten discrete time intervals over a total of 168 hours of reaction time. Since bromide ion concentration and temperature were held constant, and the chlorine dose was based on the final nonvolatile total organic carbon (NVTOC) concentration, THM formation was modeled with the independent variables: reaction time, pH, and a surrogate parameter for organic precursor. Several surrogate parameters were investigated to quantify the THM formation potential. A multiplicative surrogate (UV*TOC) representing the product of the NVTOC concentration and the UV adsorbance at 254 nm was found to be the best surrogate for activated carbon treated waters and was found to be approximately equivalent to NVTOC for alum treated waters. The THM formation was found to fit a two stage reaction with respect to reaction time; relatively rapid formation in the first eight hours followed by a slower formation from 24 to 168 hours. The data base was analyzed with a statistical software package that performs multiple linear regression analysis. Three types of models were developed: a linear model, a nonlinear model and a logarithm transform model. The models were checked for predictive accuracy by a number of methods including the examination of statistics from the regression analyses, scatterplots of predicted versus observed THM values, and the number of predicted values within 20% of the observed value. The logarithm transform model was found to be the best overall model, although other models were more accurate for specific applications as to reaction time or water type. Gel permeation chromatography (GPC) was employed to examine the molecular weight distribution of the aquatic organics in three of the eight waters and to determine the effects of alum coagulation and activated carbon adsorption on these distributions. In general, alum coagulation preferentially removed high molecular weight organics while activated carbon removed a broad spectrum of molecular weight organics.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Trihalomethanes -- Models.; Water quality management.; Water -- Pollution.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Civil Engineering and Engineering Mechanics; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Amy, Gary L.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleModeling trihalomethane formation in drinking water after alum coagulation or activated carbon adsorptionen_US
dc.creatorChadik, Paul Arthuren_US
dc.contributor.authorChadik, Paul Arthuren_US
dc.date.issued1985en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEight natural waters from throughout the United States were subjected to different degrees of alum coagulation and activated carbon adsorption treatment (not in series). The concentration of trihalomethanes (THMs) formed by the reaction between the natural aquatic organics and doses of free chlorine were determined by gas chromatography at ten discrete time intervals over a total of 168 hours of reaction time. Since bromide ion concentration and temperature were held constant, and the chlorine dose was based on the final nonvolatile total organic carbon (NVTOC) concentration, THM formation was modeled with the independent variables: reaction time, pH, and a surrogate parameter for organic precursor. Several surrogate parameters were investigated to quantify the THM formation potential. A multiplicative surrogate (UV*TOC) representing the product of the NVTOC concentration and the UV adsorbance at 254 nm was found to be the best surrogate for activated carbon treated waters and was found to be approximately equivalent to NVTOC for alum treated waters. The THM formation was found to fit a two stage reaction with respect to reaction time; relatively rapid formation in the first eight hours followed by a slower formation from 24 to 168 hours. The data base was analyzed with a statistical software package that performs multiple linear regression analysis. Three types of models were developed: a linear model, a nonlinear model and a logarithm transform model. The models were checked for predictive accuracy by a number of methods including the examination of statistics from the regression analyses, scatterplots of predicted versus observed THM values, and the number of predicted values within 20% of the observed value. The logarithm transform model was found to be the best overall model, although other models were more accurate for specific applications as to reaction time or water type. Gel permeation chromatography (GPC) was employed to examine the molecular weight distribution of the aquatic organics in three of the eight waters and to determine the effects of alum coagulation and activated carbon adsorption on these distributions. In general, alum coagulation preferentially removed high molecular weight organics while activated carbon removed a broad spectrum of molecular weight organics.en_US
dc.description.notehydrology collectionen_US
dc.description.noteDigitization note: p. 90 missing from paper original-
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectTrihalomethanes -- Models.en_US
dc.subjectWater quality management.en_US
dc.subjectWater -- Pollution.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineCivil Engineering and Engineering Mechanicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairAmy, Gary L.en_US
dc.identifier.oclc213414355en_US
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