Atmosphere hydrocarbons released into

Critics of waste incineration argue that these plants often create more environmental problems than they solve. They point out, for example, that incinerators are a major source of dioxin, mercury, and halogenated hydrocarbon release into the atmosphere. In addition, incinerators are very expensive to build and to maintain, and they provide fewer jobs to members of the surrounding community than other methods of solid waste disposal. Also, companies have a dismal record of siting incinerators in disadvantaged communities, where residents suffer the worst consequences of incinerator use. Finally, waste-to-energy incinerators are of little value in tropical and subtropical countries, where the cost of plants and the availability of additional energy sources make them impractical. 

Auto emissions have been closely monitored, and strict controls have been put Into place to minimize the amount of unbumed hydrocarbons released into the atmosphere. The Clean Air Act of 1990 was passed to help reduce hydrocarbon emissions from automobiles. The catalytic converter was developed to help react the unburned hydrocarbon and produce a less dangerous emission of carbon dioxide and water. (As a side benefit, lead had to be eliminated from gasoline because it poisoned the catalyst and made the catal3dic converter useless. The big campaign to get the lead out removed a major source of the deadly heavy metal from the environment.)... 

Water flashing in the pipestill and hydrocarbon release into the atmosphere... 

Carbon dioxide has been implicated as a contributing factor in global warming. Increased global warming has been associated with increased release of carbon dioxide into the atmosphere attributed in part to an increase in the combustion of hydrocarbon fuels. Carbon dioxide is an inevitable consequence of the complete combustion of hydrocarbons in air. If combustion devices are made more efficient, less fuel is required and less carbon dioxide is released into the atmosphere. 

The presence of polycyclic aromatic hydrocarbons in the environment is of obvious concern and, apart from specific occupational environments, human exposure to these compounds derives from combustion products released into the atmosphere. Estimates of the total annual benzo[aJpyrene emissions in the United States range from 900 tons (19) to about 1300 tons (20). These totals are derived from heat and power generation (37-38%), open-refuse burning (42-46%), coke production (15-19%) and motor vehicle emissions (1-1.5%) (19,20). Since the vast majority of these emissions are from stationary sources, local levels of air pollution obviously vary. Benzo[aJpyrene levels of less than 1 pg/1,000 m correspond to clean air (20). At this level, it can be estimated that the average person would inhale about 0.02 pg of benzo[aJpyrene per day, and this could increase to 1.5 pg/day in polluted air (21). 

In most hydrocarbon operations excess gas and vapors have to disposed of safety, quickly without environmental impact. Where the gas or vapor cannot be converted into useful energy they are routed to a remote point for safe incineration, called flaring. Flares are the most economical and customary means of disposing of excess light hydrocarbon gases in the petroleum and chemical industries. The primary function of a flare is to convert flammable, toxic or corrosive vapors to environmentally acceptable gases for release into the atmosphere. Both elevated or ground flares can be used. 

The Biocube aerobic biofilter is an ex situ off-gas filtration system that is commercially available. The technology utilizes microbes to biologically oxidize volatile organic compounds (VOCs) and complex odors. It can be used in conjunction with vapor-vacuum-extraction (VVE), a process that draws gases from subsurface soil. These gases often require further treatment before being released into the atmosphere. Biocube has been field tested and has been implemented at over 100 sites for the treatment of hydrocarbon vapors. The technology has also been successfully used for odor control at a variety of sites. In addition, the Biocube system can treat odor and VOC emissions simultaneously. The units are modular, so additional stacks can be added as needed for increased flow and/or removal rates. 

The CleanSoil process is an ex situ treatment technology that uses steam to remove hydrocarbons and chlorinated solvents from contaminated soils. The steam vaporizes the contaminants from the soil and carries them to a condenser for recovery. The water is converted back into steam and reused in the system. The remaining vapors pass through an activated carbon filter and are released into the atmosphere. The technology has been applied full-scale at multiple sites and is commercially available. 

Source Road transport is the main source of carbon monoxide and unbumed hydrocarbons in the atmosphere. Among industrial processes, the metal industry is responsible for 2.8 X 106 t/yr released into the air and 71.2% of the total emissions from industry in Europe. 

Acetaldehyde is a natural product of combustion and photo-oxidation of hydrocarbons commonly found in the atmosphere. It is an important industrial chemical and may be released into the air or in wastewater during its production and use. It has been detected at low levels in drinking-water, surface water, rainwater, effluents, engine exhaust and ambient and indoor air samples. It is also photochemically produced in surface water. Acetaldehyde is an intermediate product in the metabolism of ethanol and sugars and therefore occurs in trace quantities in human blood. It is present in small amounts in all alcoholic beverages, such as beer, wine and spirits and in plant juices and essential oils, roasted coffee and tobacco smoke (lira et al., 1985 Hagemeyer, 1991 United States National Library of Medicine, 1998). 

In our industrialized society, pollutants are being released into our atmosphere in the form of gases and chemical compounds adsorbed onto tiny particles. For example, one such class of compounds which is of concern is polynuclear aromatic hydrocarbons (PAH) since some of these compounds are reported to be carcinogenic. Three PAHs which can be formed during incomplete combustion have been identified in steel coking operations, automobile exhaust, and cigarette smoke. 

There is evidence of methane-hydrocarbon recycling in Neptune s atmosphere, and the methane there is likely broken down by sunlight. After breakdown, resultant hydrocarbons sink into Neptune s atmosphere. The hydrocarbons likely decomponse on their trip downward and release carbon which recombines with methane at depth in the upper atmosphere. 

All cars that are currently manufactured in the United States are built with catalytic converters, like the one shown in Figure 8, to treat the exhaust gases before they are released into the air. Platinum, palladium, or rhodium in these converters act as catalysts and increase the rate of the decomposition of NO and of NO2 into N2 and O2, harmless gases already found in the atmosphere. Catalytic converters also speed the change of CO into CO2 and the change of unbumed hydrocarbons into CO2 and H2O. These hydrocarbons are involved in the formation of ozone and smog, so it is important that unbumed fuel does not come out in the exhaust. 

VOCs are generally low-molecular-weight aliphatic and aromatic hydrocarbons like alcohols, ketones, esters, and aldehydes.19 Typical VOCs include benzene, acetone, acetaldehyde, chloroform, toluene, methanol, and formaldehyde. These compounds are typically considered to be regulated pollutants, as they can cause photochemical smog and depletion of the ozone layer if they are released into the atmosphere. They are not normally produced in the combustion process, but they may be contained in the material that is being heated, such as in the case of a contaminated hazardous waste in a waste incinerator. In that case, the objective of the heating process is usually to volatilize the VOCs out of the waste and to combust them before they can be emitted to the atmosphere. 

Formaldehyde and other aldehydes are receiving increasing attention both as toxic substances and as promoters in the photochemical formation of ozone in the atmosphere. They are released into residential buildings from plywood and particle board, insulation, combustion appliances, tobacco smoke, and various consumer products. Aldehydes are released into the atmosphere in the exhaust of motor vehicles and other equipment in which hydrocarbon fuels are incompletely burned. A sensitive method for analyzing aldehydes and ketones is based on the sorption of these compounds to an SPE sorbent and their subsequent reaction with 2,4-dinitrophenylhydrazine (DNPH) on the sorbent. They are then analyzed as their hydrazones by HPLC (Fig. 7.9). A gradient analysis by HPLC may separate as many as 17 components with detection by ultraviolet (UV) light. 

When released into the atmosphere, NO rapidly combines with O2 to form NO2. Nitrogen dioxide and other gases emitted by an automobile, such as carbon monoxide (CO) and various unbumed hydrocarbons, make automobile exhaust a major source of air pollution. 

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