Emissions containment

Catalytic incineration has been appHed in the abatement of chlorinated VOC emissions in the pharmaceutical industry. The major compounds in the emission mixture are dichloromethane, perchloroethylene, dimethylformamide, oxitol, and toluene. The incinerator operates normally at 400-500 °C, but when emissions contain perchloroethylene the temperature is increased up to 500-600 °C. The emission mixture also contains water, which pushes the selectivity further toward HCl formation instead of formation of CI2. After oxidation, the product gases are washed with NaOH scrubbers. The purification level of over 99% can be achieved with the incinerator, the activity of which has been shown to be very stable after one year of continuous operation [69-71]. 

Diesel emissions contain low concentrations of carbon monoxide and hydrocarbons. The major problem with diesel emissions are nitric oxides and particles as these are the most difficnlt to rednce. 

Bencko V, Wagner V, Wagnerova M, et al. 1983. Immuno-biochemical findings in groups of individuals occupationally and nonoccupationally exposed to emissions containing nickel and cobalt. J Hyg Epidemiol Microbiol Immunol 27 387-394. 

Another evidently radiation-induced band occurs in the orange part of spectrum. Under long waved UV and visible excitations the band peaking at 600 nm is detected with half-width of 95 nm (Fig. 5.66a). Excitation spectrum of this emission contains for maxima peaking at 345,360 and 410 nm (Fig. 5.66b). The band is evidently not symmetrical with shoulder at 625 nm, but such form remains in all time-resolved spectra with different delays and gates and does not resolved to several emission bands. This band can be detected with extremely narrow gate width, which is a strong evidence that its decay time is very short, approximately 10-12 ns, which is on the border of our experimental system alrility. At 40 K the band becomes extremely intensive, while its spectrum and decay time remain practically the same. 

Preannihilative electrochemical oxidation of the phenanthrene anion has given a green emission13,64 spectrally nearly identical to the previously reported room-temperature phenanthrene phosphorescence which is a single broad peak.71 Chemical oxidation of the chrysene anion with Wurster s blue perchlorate produced an emission containing three bands at 19,800, 18,600, and 17,400 cm"1 which seem to correspond to the known phosphorescence bands of chrysene (19,500,18,500, and 16,600 cm-1). Chemical oxidation of the radical anion of N-methylcarbazole has possibly led to phosphorescent emission from this triarylamine.7... 

Another important application of heterogeneous catalysts is in automobile catalytic converters. Despite much work on engine design and fuel composition, automotive exhaust emissions contain air pollutants such as unburned hydrocarbons (CxHy), carbon monoxide, and nitric oxide. Carbon monoxide results from incomplete combustion of hydrocarbon fuels, and nitric oxide is produced when atmospheric nitrogen and oxygen combine at the high temperatures present in an... 

Treatment of air emissions containing silver is not a concern as atmospheric emissions rarely approach the federal threshold limit value for occupational exposure of 0.01 mg/m (Smith and Carson 1977). 

Often, many simultaneously occurring pollutants or contaminants determine an environmental problem. In industry, agriculture, and households, products are often mixtures of many compounds. The process of production and consumption is accompanied by emissions and consequently by contamination. One example is the use of toxaphene in the past, a very complex mixture of polychlorinated camphenes, as a pesticide. Technical toxaphene consists of more than 175 individual compounds. A second example is industrial and domestic emissions resulting from the combustion of fossil fuels. The emissions contain both a mixture of gases (SO2, NOx, CO2, etc.) and airborne particulate matter which itself contains a broad range of heavy metals and also polycyclic aromatic hydrocarbons (PAH). 

Emissions from the prilling and granulation sections of AN and CAN plants can be treated by a range of abatement equipment. Particulate material from some granulation plants is relatively coarse in particle size, whereas the prill tower emissions contain very fine particles. Candle filters are normally required for a prill tower emission. They can abate particulate emissions down to 15 mg/m3 of air. For coarser material dry devices such as bag filters or dry cyclones are used. Particulate emissions can be of higher concentration, perhaps up to 30 to 50 mg/m3, but the recovered material is a solid that can more readily be recycled to the process. 

The isomer profiles of TeCDTs in the selected-ion monitoring chromatograms of stack gas samples from waste incineration and from pulp mill effluents are quite different. Still, the concentrations of TeCDTs in the stack gas samples were quite high, while the concentrations in pulp mill effluents were very low. The stack emissions contain more isomers which have shorter retention times in the HP-5 column than the pulp mill effluents. This may indicate that the TeCDTs are formed in a different way in waste combustion and in pulp bleaching [15]. SIM chromatograms with the exact value of the (M+2)+ ion of TeCDTs (321.8759) from a stack gas sample and from a pulp mill effluent sample are shown in Fig. 1. 

The primary routes of potential human exposure to coke oven emissions are inhalation and dermal contact. Occupational exposure to coke oven emissions may occur for those workers in the aluminum, steel, graphite, electrical, and construction industries. Coke oven emissions can have a deleterious effect on human health. Coke oven emissions contain literally several thousand compounds, several of which are known carcinogens and/or cocarcinogens including polycyclic organic matter from coal tar pitch volatiles, jS-naphthylamine, benzene, arsenic, beryllium, cadmium, chromate, lead, nickel subsulfide, nitric oxide, and sulfur dioxide. Most regulatory attention has been paid to coal tar pitch volatiles. 

Combustion of coal produces many of the same ultimate water pollutants as combustion of petroleum does, that is, PAHs. Coal burning, however, produces greater quantities of metals, sulfur dioxide, and haloacids. Coal combustion stack emissions contain significant quantities of arsenic, mercury, selenium, copper, and tin. I25 Sulfur dioxide is ultimately converted to sulfuric acid in the air. Sulfuric acid and the haloacids (HF, HC1,... 

CAA amendment of 1990 Regulates air emissions containing PAHs. Specific industries impacted by this regulation include power plants, petroleum processing facilities, and steel manufacturing plants. 

Combustion particles are of complex chemistry, carrying most of the trace elements, toxins or carcinogens generated from the combustion process. Combustion of different types of fuels results in emissions of various trace elements which are present in the fuel material. In most cases there is not just one specific element that is related to the combustion of a particular fuel, but a source profile of elements [2]. For example, motor vehicle emissions contain Br, Ba, Zn, Fe and Pb (in countries where leaded petrol is used) and coal combustion results in the emission of Se, As, Cr, Co, Cu and Al. For comparison, the crustal elements include Mg, Ca, Al, K, Sc, Fe and Mn. Since most of the trace elements are nonvolatile, associated with ultrafine particles and less prone to chemical transformations, they often remain in the air for prolonged periods of time in the form in which they were emitted. 

The composition of PAH emissions varies with the combustion source. For example, emissions from residential wood combustion contain more acenaphthylene than other PAHs (Perwak et al. 1982), whereas auto emissions contain more benzo[g,h,i]perylene and pyrene (Rogge et al. 1993a Santodonato et al. 1981). PAHs in diesel exhaust particulates are dominated by three- and four-ring compounds, primarily fluoranthene, phenanthrene, and pyrene (Kelly et al. 1993 Rogge et al. 

As in atomic emissions, some interferences from molecular species occur and must be corrected for. Molecular emissions contain much broader bandwidths and... 

---