Dioxin primary pollutant

Extensive data were collected on primary pollutants (phenols, and PAHs) and on secondary pollutants (oil, suspended and dissolved solids, COD, dioxins, and VOC s). The results of this project demonstrated the ability of the formed-in-place membrane, operating in a cross-flow mode, to minimize fouling, and to remove polynuclear aromatic hydrocarbons from the contaminated feed water. As operated, rejection of the PAHs appears to increase with the number of aromatic rings. However, similar correlations appear to exist with molecular weight as well as with the partition coefficient reflecting hydrophobicity. The permeate, accounting for approximately 80% of the feedwater, contained only about 12% of the predominant PAHs, naphthalene and phenanthrene. 

For either plant type, incineration, or fuel type, these factors must be empirically determined and controlled. Because dioxins as effluents are concerned, it is possible to reduce I-TE values from about 50 ng/m to about 1 ng/m. Additional secondary measures (filter techniques) are therefore necessary for obtaining the lower limit value of 0.1 ng/m. Secondary measures are special filter techniques for pollutants formed in nongreen processes, also called end-of-pipe technology. The main part of technical incineration plants consists of filter devices, mostly coke as adsorbent is used, which must be decontaminated later by itself by burning in hazardous-waste incinerators. The inhibition technology, discussed later, is related on principles of primary (green) measures for a clean incineration method. 

In other cases, stationary phases have been tailored to achieve specific separations. In one case, a new stationary phase was designed to achieve the separation of a particular mixture of volatile priority water pollutants whose separation has posed a real problem (6, 7). A serendipitous finding was that this new stationary phase, DB-1301, also promises to be very useful for the separation of some chlorinated pesticides. Nor have we reached the end of this road an Immobilized form of 2330, with utility for those Interested In dioxins, In positional Isomers of the fatty acids, and In other challenging separations, will soon be available. Fused silica columns with bonded particulate materials, reminiscent of the old PLOT-type columns, are also available. The primary utility of the PLOT-type columns currently available Is for fixed gas analysis, but newer types on the horizon will permit a choice of adsorptive-type separations, partition-type separations, or a combination of both. 

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are the most hazardous environmental pollutants that have received prolonged attention by the scientific community and by environmental regulation. These compounds are not commercially produced but can be formed during combustion processes, such as municipal waste incineration, in which halogenated compounds are exposed to very high temperatures. Other primary sources of formation of these compounds are related to various chemical processes that result in contaminated products and waste. Although there are theoretically 75 PCDFs and 135 PCDDs, only 17 of them... 

---