47    ORIGINS OF VOLATILE HALOGENATED ORGANIC
COMPOUNDS IN CHLORINATED EFFLUENTS FROM
WASTEWATER TREATMENT PLANTS CONTAINING
DIFFERENT INDUSTRIAL WASTE CONTRIBUTIONS
Joseph V. Hunter, Professor II and Chairman
Gregory Toffoli, Research Assistant
Department of Environmental Science
Rutgers University
New Brunswick, New Jersey 08903
Robert Mueller, Principal Environmental Specialist
New Jersey Department of Environmental Protection
Office of Science and Research
Trenton, New Jersey 08625
INTRODUCTION
Although it has been considered by investigators in the public health area as one of the barriers to
the spread of waterborne infectious diseases through the protection of recreational and shellfish uses
of receiving waters, wastewater treatment plant effluent disinfection employing chlorination has
caused considerable controversy over the past several years.
Excepting such potential considerations as cost, objections to such disinfection through chlorination fall into two categories. The first involves the concerns centered about the release of a "toxic"
disinfectant to the receiving waters, that is, "residual" chlorine. The second involves the concerns
centered about the oxidative nature of chlorine. As an oxidant, hypochlorite (the reaction product of
gaseous chlorine and water) may oxidize an organic compound through the removal of hydrogen or
the addition of oxygen or through the replacement of hydrogen by chlorine or even the addition of
chlorine to double bonds. The first two reactions are typical of oxidative processes that occur naturally in receiving waters and so are considered relatively unobjectionable. The addition of chlorine to
organic molecules, however, may cause the formation of chlorinated organics having objectionable
physiological activities —such as odor, toxicity, mutagenicity or carcinogenicity. Thus, it is this second
type of reaction that causes concerns over the discharge of such organics to the aquatic environment.
A number of studies [1,2,3] have confirmed the presence of halogenated organics in chlorinated
wastewater treatment plant effluents. This was to be expected since the concentration of organic
compounds in effluents should act as precursors in a manner analogous to the natural organics in
surface waters which can produce substantial quantities of trihalomethanes subsequent to chlorination. As effluents from plants treating a mixture of domestic and industrial wastes would be expected
to have a greater diversity of organics than plants treating only domestic wastes, the chlorination of
effluents from the treatment of domestic/industrial waste mixtures might be expected to produce a
greater diversity and concentration of organics than the chlorination of effluents from domestic
wastes only.
A previous paper [4] described an attempt to establish this relationship. In this study, the concentrations of the relatively volatile halogenated compounds were determined in unchlorinated and chlorinated effluents from treatment plants treating wastewaters containing 0%, 25%, and 50% industrial
wastewater contributions. Unfortunately, the large number and high concentrations of halogenated
organics in the unchlorinated effluents containing industrial waste contributions rendered definitive
conclusions impossible, although ii could be suspected that if industrial wastes made substantial
contributions of precursors for the formation of halogenated organics, this would have been obvious
despite the high background levels. To determine whether or not the premise of this study was correct,
the study was repeated in a considerably more exacting manner. The results of this study are described
in this paper.
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