Emission dioxins

E Consumers of animal-based foods Incineration emissions Dioxins Uptake into animals through contaminated feed, storage in animal tissues Ingestion... 

See also Coke Oven Emissions Dioxins Organochiorine Insecticides Poiychiorinated Biphenyis (PCBs) Poiycy-ciic Aromatic Hydrocarbons (PAHs) Voiatiie Organic Compounds (VOC). 

Experimental and theoretical studies are presented from a laboratory-scale thermal destruction facility on the destructive behavior of surrogate plastic and nonplastic solid wastes. The nonplastic waste was cellulosic while the plastic waste contained compounds such as polyethylene, polyvinyl chloride, polystyrene, polypropylene, nylon, rubber, and polyurethane or any of their desired mixtures. A series of combustion tests was performed with samples containing varying composition of plastic and nonplastic. Experimental results are presented on combustion parameters (CO, excess air, residence time) and toxic emissions (dioxin, furan, metals). 

Persistent organic pollutant emissions (dioxins/furans and PAHs) are reduced by combustion control and by cleaning gas devices known as end-of-pipe technologies (Fig. 5.2). 

However, in some countries such as Germany there is considerable reservation to adding scavengers because of their possible contribution to dioxin emissions. Furthermore, for lead contents of 0.15 g/1, the need for scavengers is questionable. It is possible that the leaded fuels sold in the coming years will contain neither chlorine nor bromine. 

R. G. Barton, W. O. Clark, W. S. Lanier, and W. R. Seeker, "Dioxin Emissions During Waste Incineration," presented at Spring Meeting Western States Section of the Combustion Institute, Salt Lake City, Utah, 1988. 

Dioxin and Furan Emissions. The emissions of polychlorinated dibenzo-/)-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDF) from incinerators (4) are of interest to the pubHc, scientists, and engineers. The U.S. EPA classifies 2,3,7,8-tetrachlorodibenzo-/)-dioxin (2,3,7,8-TCDD) as the most potent carcinogenic compound it has evaluated. It is also Hsted as the agency s most potent reproductive toxin (4). 

In the United States, the Clean Air Act of 1990 requires plants to reduce emissions of 189 toxic and carcinogenic substances such as chlorine, chloroform, and 2,3,7,8-TCDD (dioxin) by 90% over the 1990s. The U.S. Environmental Protection Agency is working to develop standards based on maximum achievable control technologies and the industry has invested bUHons of doUars in capital investments to retrofit or rebuUd plant equipment to meet these measures. 

In 1990, a test using scrap tires (2x2 in. I DE) to generate steam for electricity was conducted at the Elexsys plant. The I DE replaced 20% of the plant s coal. Results showed that IDE is an environmentally sound fuel. Particulate emissions were reduced by the lower ash content of IDE, volatile organic compounds (VOC) were reduced because of more efficient burning of I DE compared to coal, and carbon dioxide emissions were reduced because I DE contains half the fixed carbon found in coal. Nitrogen oxide, chlorine emissions, and metals were also reduced, and ferrous metals and dioxins were nondetectable (7). 

H. G. Rigo, A. J. Chandler, and W. S. Lanier, The Relationship Between Chlorine in Waste Streams and Dioxin Emissions From Waste Combustor Stacks, The American Society of Mechanical Engineers, New York, 1995. 

Most carbon adsorption units use granular activated carbon (GAC). The powdered form of activated carbon (PAC) typically is less than 100 microns in diameter and may be used to reduce dioxins in incinerator emissions (2) and in the treatment of drinking water and wastewater treatment (see the section on "Activated Sludge"). 

Optimized modern dry scrubbing systems for incinerator gas cleaning are much more effective (and expensive) than their counterparts used so far for utility boiler flue gas cleaning. Brinckman and Maresca [ASME Med. Waste Symp. (1992)] describe the use of dry hydrated lime or sodium bicarbonate injection followed by membrane filtration as preferred treatment technology for control of acid gas and particulate matter emissions from modular medical waste incinerators, which have especially high dioxin emissions. 

Chemical Volume Reduction Incineration has been the method commonly used to reduce the volume of wastes chemically. One of the most attractive features of the incineration process is that it can be used to reduce the original volume of combustible sohd wastes by 80 to 90 percent. The technology of incineration has advanced since 1960 with many mass burn facihties now have two or more combustors with capacities of 1000 tons per day of refuse per unit. However, regiila-tions of metal and dioxin emissions have resulted in higher costs and operating complexity. 

MWCs Organic Emissions The NSPS limits organic emissions to a total dioxin plus furan emission hmit of 30 ng/dscm (at 7 percent O9 diy volume). This level is approximately equivalent to a toxic equivalent (TEQ) of 1.0 ng/dscm, using the 1990 international toxic equivalency fac tor (1-TEF) approach. 

In general, the environmental consequences resulting from emissions generated by the combustion of treated wood and the chemicals used to treat them are not well understood. Combustion of the materials involved in the incident unquestionably produced hazardous products of incomplete combustion emissions (e.g., dioxins and furans). 

The principal PIC for penta and penta-treated wood would include volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), dioxins and furans, as well as SOj, COj, NO, and HCl. Penta would be expected to have undergone a very high destruction efficiency (DRE) during the fire (> 99.99%). Among the VOC emissions, the following chemicals likely contributed to air pollution problems benzene, bromobenzene, chloromethane, 1,3-butadiene, iodomethane, acetone, chloroform, and 1,2-dichloroethane. 

Dioxin (2,3,7,8-TCDD) zero 0.00000003 Reproductive difficulties increased risk of cancer Emissions from waste incineration and other combustion discharge from chemical factories... 

Compare the inhalation risk for tlie emission of 100 pg/m of arsenic willt unit risk of 3.30. x 10 (pg/nv ) ) and dio.xin/dibenz.ofunm willi unit risk of 3.80x10 (pg/m ) ). Also how much arsenic is equivalent to 100 lb of dioxin/dibciizofuran from an inhalation risk perspective ... 

Use of some biomass feedstocks can increase potential environmental risks. Municipal solid waste can contain toxic materials that can produce dioxins and other poisons in the flue gas, and these should not be burned without special emission controls. Demolition wood can contain lead from paint, other heavy metals, creosote, and halides used in presen a-tive treatments. Sewage sludge has a high amount of sulfur, and sulfur dioxide emission can increase if sewage sludge is used as a feedstock. 

Natural gas will continue to be substituted for oil and coal as primary energy source in order to reduce emissions of noxious combustion products particulates (soot), unburned hydrocarbons, dioxins, sulfur and nitrogen oxides (sources of acid rain and snow), and toxic carbon monoxide, as well as carbon dioxide, which is believed to be the chief greenhouse gas responsible for global warming. Policy implemented to curtail carbon emissions based on the perceived threat could dramatically accelerate the switch to natural gas. 

Concern has been expressed about the possible formation of dioxins and furans. However, measurements during experiments indicated that the emissions of dioxins and furans were not significantly elevated. Dioxin emissions with or without plastic input appeared to be about a factor of 100 below the standard of 0.1 ng/Nm TEQ TCCD (toxicity equivalent in relation to the toxic dioxin TCCD) (a.7). This might be due to the benefit of the strongly reducing atmosphere and the high temperature of 2100 °C. In total, until now the conclusion has been that at current PVC levels in MSW, pretreatment for chlorine removal is unnecessary. 

The LCA of Heyde and Kremer (a.6) gives an extensive review of emissions and resource use. However, by and large one could assume that the emissions by using plastics as reducing agent will be more or less equal to the emissions that would occur if another reducing agent were to be used. For a discussion on the (probably limited) relevance of dioxin emission see Section 3.5.3. 

Test results are presented and discussed following trials in which energy recovery of mixed plastics domestic waste and municipal solid waste was carried out by means of co-combustion. The research also involved the collection of data relating to emissions, and the levels of halogens, dioxins and furans and heavy metals within the mixed plastics waste. 

It has been suggested that the photochemical reaction of pentachlorophenol in aqueous solution to produce octachlorodibenzo[l,4] dioxin and some of the heptachloro congener could account for the discrepancy between values for the emission of chlorinated dioxins and their deposition, which is significant for the octachloro congener (Baker and Hites 2000). 

Wang, L., Lee, W., Tsai, P, Lee, W., and Chang-Chien, G., Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans from stack flue gases of sinter plants, Chemosphere, 50(9), 1123-1129, 2003. 

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