Evaluation of Polychlorinated Dibenzo-p-dioxin/Dibenzofuran (PCDD/F) Emission in Municipal Solid Waste Incinerators

Abstract

This paper summarizes an engineering approach taken for 10 commercial MSW incinerators to formulate a basis for PCDD/F emission reduction schemes and to interpret the measurement results before and after the plant modifications of moderate scale. Control strategy of PCDD/F emission from the operating incinerators can be established on the basis of the interpretation of reliable measurements as well as understanding of the formation/destruction processes. The fate of PCDD/F is known to be influenced by the flue gas subprocesses: the initial formation/ oxidation in the combustion chamber, reformation through synthesis, removal by adsorption, and catalytic destruction. A simplified model is proposed for PCDD/F level at various stages of the flue gas, basically integrating the reaction kinetic rates at the corresponding state. Since the kinetic rate is dependent on temperature, time-temperature history of the flue gas is considered as the important input data. Using the plant design and operating conditions, this global prediction model calculates the PCDD/F level not only at the stack but also at the process midstream. The model predictions are discussed along with measurement results from the different design of incinerator plants.

The formation of dioxins in combustion systems

“…If the ash concentration is a typical 0.5 g N m −3 , this is equivalent to 75 to 7500 ng PCCD/F N m −3 s −1 . In the furnace section (gas phase) of MSW incinerators, Shin et al [5] have reported values of the order of 6 ng PCCD/F N m −3 s −1 . Thus the rates in the low-temperature section (homogeneous reactions) are much higher than in the furnace section (heterogeneous reaction).…”

“…The ratio of total PCCD/F mass to the mass of I-TEQ components ranged from 5 to 100 in the emissions from 17 different municipal and medical waste incinerators [3,4]. Shin et al [5] give a mean value of 12 for MSW emissions from Korean incinerators. The figure depends on the distribution of congeners, which has been found to be relatively constant for MSW emissions.…”

Biotransformation of 1,2,3-Tri- and 1,2,3,4,7,8-Hexachlorodibenzo-p- Dioxin bySphingomonas wittichiiStrain RW1

“…Consequently, numerous studies have been carried out to elucidate the aerobic (7,9,19) bacterial degradation of PCDD/Fs, compounds produced by incineration processes and as unwanted by-products of the synthesis of pesticides and herbicides (4,17). However, naturally occurring microorganisms have evolved to degrade and mineralize many, but by no means all, of these compounds.…”

Biotransformation of 2,7-Dichloro- and 1,2,3,4-Tetrachlorodibenzo- p -Dioxin by Sphingomonas wittichii RW1

“…These halogenated compounds have become ubiquitous pollutants because they can be accidentally released (10) after they are formed as unwanted by-products during synthesis of haloaromatic compounds, such as agricultural pesticides (3), or during incineration of industrial or domestic wastes (12,16). In addition to diaryl ethertransforming isolates belonging to genera such as Terrabacter (7,11) and Pseudomonas (7), workers have isolated and characterized several strains belonging to the genus Sphingomonas which are able to use diaryl ethers, such as dibenzofurans and dibenzo-p-dioxins, as sole sources of carbon and energy (for reviews, see references 2 and 21).…”