Contamination by volatile organic

Contamination by volatile organics becomes of increasing concern in higher pressure boilers because they can cause severe turbine damage. 

Kerfoot HB. 1987. Soil-gas measurement for detection of ground water contamination by volatile organic compounds. Environ Sci Technol 21 1022-1024. 

Ariel Industries, Inc. (Ariel), has designed and manufactured the Ariel SST low-temperature thermal desorber for the ex situ treatment of soil contaminated with volatile organic compounds (VOCs) and hydrocarbons. The system is portable and is used to heat sediment to approximately 900°F, removing moisture and contaminants from the soil. The technology had been offered by Ariel industries on the commercial level, but the company is no longer in the thermal desorption business. 

In 1997, it was estimated that it would cost approximately 30 to 50 per ton to remediate soil contaminated with volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) using HeatTrode technology. The computer model estimate was based on inputs from testing performed by the University of Buffalo and the United States Air Force (D17162K,... 

The volatile oil as it comes from the still is in a crude state, being contaminated by volatile substances which arc formed during the distilling process by the action of the steam upon the less stable plant constituents, decomposing them into volatile organic substances, which, although trilling in quantity, nevertheless tend to affect the color, odor, and taste of the oil. 

The risks of environmental contamination and to human health caused by volatile organic compounds have driven a lot of research designed to eliminate or remedy its deleterious effects. Several of these compounds, such as phenol and BTEX compounds (benzene, toluene, ethyl benzene and the isomers of xylene) are found in effluents from oil refineries, and they are important contaminants due to their high toxicity (Akhtar, 2007). 

Great care is required if truly representative samples of seawater are to be collected for DOC determinations (see general comments about sampling elsewhere in this volume, e.g., Chapters 1, 2 and 15). A major potential problem is contamination. Sources of contamination can be very variable, and clearly materials which come into direct contact with samples must be free of soluble organic materials specific approaches to cleaning are described below. A particular problem for DOC samples is contamination by volatile water soluble compounds such as ketones and alcohols, which may be in common use in laboratories, and can be introduced through the vapour phase from the atmosphere into samples. It is sensible to limit exposure of the sample to the laboratory atmosphere and to have dedicated areas for this type of work away from potential contamination sources. 

Environmental Problems—This section describes N Reactor operational activities that affected the environment. The affected environs are groundwater contamination (radionuclides, volatile organics, polychlorinated biphenyls (PCB), metals, and other Inorganics) soil contamination (surface and vadose zone contamination from radionuclides and organic compounds) biota contamination (flora [vegetation] and fauna [animals] from radionuclide uptake by plants or Ingestion by animals) and evaluated radiation at the Columbia River (unshielded sediments In the 1301-N Liquid Waste Disposal Facility). 

Thermal Desorption. Thermal desorption is an innovative treatment that has been appHed primarily to soils. Wastes are heated to temperatures of 200 to 600°C to increase the volatilization of organic contaminants. Volatilized organics in the gas stream are removed by a variety of methods including incineration, carbon adsorption, and chemical reduction. 

Volatile organic contaminants occur primarily in groundwaters as a result of the disposal of industrial solvents on the ground or in soakage pits. The removal of these compounds has best been accompHshed by the use of air stripping or adsorption on activated carbon. 

Potable Water Treatment. Treatment of drinking water accounts for about 24% of the total activated carbon used in Hquid-phase apphcations (74). Rivers, lakes, and groundwater from weUs, the most common drinking water sources, are often contaminated with bacteria, vimses, natural vegetation decay products, halogenated materials, and volatile organic compounds. Normal water disinfection and filtration treatment steps remove or destroy the bulk of these materials (75). However, treatment by activated carbon is an important additional step in many plants to remove toxic and other organic materials (76—78) for safety and palatability. 

Important intermedia transfer mechanisms affecting soil contaminants include volatilization or resuspension to the atmosphere and biouptake by plants and soil organisms. These, in turn, introduce contaminants into the food chain. 

Some organic contaminants are volatilized and escape from the soil surface and must be collected by a vacuum system. Inorganics and some organics are trapped in the melt, which, as it cools, becomes a form of obsidian or very strong glass. When the melt is cooled, it forms a stable noncrystalline solid. 

Li and Hsiao [143] provide a useful approach to the environmental problem of removing (by stripping) volatile organics from solution in a contaminated water stream by using fresh air as the stripping medium. It should be noted that a number of industrial firms perform this stripping with steam. The mass balance on the VOC component around the column (trayed or packed) as shown in Figure 8-55 uses the symbols of Reference 143. 

---