Abstract/Details

Identification and fate of mixed ozonation/chlorination and ozonation/chloramination by-products in drinking water treatment


2002 2002

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Abstract (summary)

Disinfection may cause a dilemma for drinking water treatment plants using chlorine for the maintenance of a disinfectant residual in distribution systems. On one hand the chlorine residual should ensure microbially safe drinking water, but on the other hand harmful disinfection by-products (DBPs) can be formed from the reaction of natural organic matter (NOM) with chlorine.

Many utilities are looking to the combined use of ozonation for primary disinfection, followed by chlorine or chloramines as a means of minimizing DBP formation while maintaining a stable disinfectant residual. However, these combinations may lead to a new spectrum of by-products that differs from that produced when a single disinfectant is used. The formation of mixed ozonation/chlorination and ozonation/chloramination by-products is the subject of this dissertation.

A diverse collection of precursor compounds that produce a large amount of “unknown” total organic halides (TOX) was identified by performing bench scale tests to simulate chlorination of known ozonation by-products. Simple mono- and di-carboxylic acids were not found to react with chlorine. Di-aldehydes, α-keto-acids, and α-hydroxy-acids are oxidized by chlorine but do not show TOX formation. However, chlorine does become incorporated in β-diketones. Oxalacetic acid, 3-methyl-2,4-pentanedione, acetonedicarboxylic acid, and malic acid were found to form more “unknown TOX” than common chlorination by-products. Usually, the chlorine demand as well as the TOX increase with decreasing pH and increasing chlorination time.

The identification of “unknown TOX” was the second major goal of this work. Quenched samples from the model compound studies were derivatized with pentafluorobenzylhydroxylamine (PFBHA), extracted with methyl-tert-butyl-ether (MtBE), and silylated with bis-(trimethylsilyl)-triflouroacetamine (BSTFA). Malic and acetonedicarboxylic acids were each found to produce a previously-unknown byproduct after reacting with chlorine. The identity of this and other new by-products was suggested based on the mass spectra. Surprisingly, mono-chlorinated species were found to be more abundant than di-chlorinated species in all cases.

The third phase of this research showed that a substantial amount of “unknown TOX” is also formed in distribution systems where chlorine is used as final disinfectant. The “unknown TOX” ranged between 60% and 80% of the measured TOX.

Indexing (details)


Subject
Environmental engineering;
Sanitation
Classification
0775: Environmental engineering
0554: Sanitation
Identifier / keyword
Applied sciences, Chlorine, Disinfection, Drinking water, Ozone, Water treatment
Title
Identification and fate of mixed ozonation/chlorination and ozonation/chloramination by-products in drinking water treatment
Author
Hartmann, Caroline M.
Number of pages
226
Publication year
2002
Degree date
2002
School code
0118
Source
DAI-B 63/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
049371510X, 9780493715100
Advisor
Reckhow, David A.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3056236
ProQuest document ID
275622249
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/275622249
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