Section Fifteen
CHEMICAL TREATMENT METHODS
52    DIOXIN: TREATMENT WITH OZONE
Dieter Von Der Mark, Vice President
Schmidding-Werke
Koln, West Germany
A. Rony Joel, Division Manager
Capital Controls Company, Inc.
Colmar, Pennsylvania 18915
Hans H. Rump, Head of Research
Institute Fresenius
Koln, West Germany
INTRODUCTION
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) belong to
the family of aromatic ethers, i.e. oxygen-bonded phenyl rings. The group of PCDDs contains a total
of 75 different chlorine homologs and position isomers, the group of the PCDFs contains an additional 135 compounds. The number of chlorine atoms in the molecule is expressed by the prefix
mono-(l) to octa-(8). The position of the chlorine atoms are identified by means of a systematic
numbering (Figure 1).
PCDDs and PCDFs are regarded as anthropogenic substances, as a biogenic process of formation
has not yet been discovered. Experiences show that there are many possibilities for the formation of
such families. The most important sources are, according to Hutzinger,1 the chemical industry and
combustion processes. These compounds typically occur as a contaminant of a product stream.
Examples of processes in which PCDDs and PCDFs can be produced are production and subsequent
treatment of chlorophenols, production of chlorinated biphenyls, synthesis of further chlorinated
aromatics, and other processes involving chlorine chemistry. Esposito et al.2 has established lists of
organic chemicals and biocides, during the production of which dioxins and furans can be formed.
Waste products containing dioxins have been stored for decades at waste disposal facilities without
any special precautions. Dioxin-containing drainage water, or leachate, constitutes a high danger
potential for human beings and the environment. Furthermore, there is a danger due to the long term
use of herbicides, fungicides, and insecticides, which can be contaminated with PCDDs and PCDFs.
Due to the physio-chemical properties of these two classes of substances, concentrating effects in the
food chain cannot be excluded. Of the 210 different compounds in these two classes, the 2,3,7,8-
chlorine substituted compounds are to be regarded as especially toxic.3 No toxicity worth mentioning
was discovered in the specific octa-chlorine compounds, in spite of the existing 2,3,7,8-position of the
chlorine atoms, whereas the 2,3,7,8-tetrachloro-dibenzo-p-dioxin, showed the highest toxicity of these
PCDD PCDF
Figure 1.    Structural formulas of the dibenzo-p-dioxins and dibenzo furans (X and Y indicate the
number of chlorine atoms).
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