Volatile Organic Compounds VOCs Contamination

In an environment of PEMFC residential applications as backup power supplies, some volatile organie eompounds (VOCs), including benzene and toluene, exist due to decorative materials. For military applications, the VOCs are different. In battlefields, chemieal warfare ean release significant amount of VOCs such as Sarin, HCN, and so on [36]. These VOCs could result in disastrous degradation of PEMFC performanee. 

The effect of benzene eontamination on cell performance is dependent on the operating current density. When a fuel cell was fed with air containing 50 ppm benzene over a period of 30 minutes, at 50 mA/cm, a 5% reduction of power output was observed in comparison with pure air. At 200 mA/cm, the output reduction was more than 38%. These performance drops were not fully reeovered after the benzene was shut off and the fuel eell was purged wifli pure air over a period of 10 minutes [36]. 

Toluene contamination in air could affect fuel eell performanee, mainly resulting in performance degradation in the kinetic region (low current densities). This contamination also results in easy flooding at the cathode side, possibly changing the hydrophilicity of the cathode eatalyst layer. The mechanism of toluene contamination is not clear [56]. 

Fuel cell cathode contamination caused by chemical warfare gases is disastrous. With 1780 ppm HCN in air, the power output of a PEMFC was only 13% of the original value, and the degraded performanee was only partly recoverable. After 30 minutes of purging with neat air, the output reeovered to 45% of the original value [36]. 

Contamination with Sarin and sulfur mustard is even more disastrous as compared with HCN. For a PEMFC fed with air containing 15 ppm sulfur mustard, the power output was only 13% of the original value. This degradation is totally unrecoverable. The same is true for Sarin. Air contaminated with 170 ppm Sarin resulted in a 70% performance degradation, and no reeovery was observed when the cell was purged with pure air [36]. 

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Soil vapor extraction (SVE) is a relatively new yet widely applied technology for the remediation of soils contaminated with volatile organic compounds (VOC) in the unsaturated zone above the water table (vadose zone). The process consists of generating an airstream through the contaminated soil subsurface in order to enhance the volatilization of organic contaminants and thus remove them from the soil matrix.913... 

Blood samples for analysis of volatile organic compounds (VOCs) including hexachloroethane should be collected into containers from which VOC contamination has been reduced (Ashley et al. 1992). Potassium oxalate/sodium fluoride is the recommended anti-coagulant. Blood samples should be placed on ice or refrigerated shortly after collection, and Ashley et al. (1992) recommend that analysis for VOCs be completed within 14 days. 

The System 64MT low-temperature thermal desorption (LTTD) system is a commercially available ex situ thermal desorption technology. This system uses a countercurrent flow rotary drier to heat soils contaminated with volatile organic compounds (VOCs) to temperatures sufficient to cause contaminants to volatilize and physically separate from the soU. Filter bags remove particulate matter and afterbumers/oxidizers are used to destroy organic constituents that remain in the filtered airstream. 

Advanced Soil Technologies (AST) offers the AST thermal desorption system for the treatment of soil contaminated with volatile organic compounds (VOCs). The process heats the soil to remove the targeted contaminants, which are then destroyed in a secondary treatment chamber. The technology has been available commercially. RIMS was unable to contact the vendor. 

It is effective at treating perchlorate in the presence of other contaminants, such as nitrate, chlorate, sulfate, ammonium, dissolved solids, dissolved metals, and volatile organic compounds (VOCs). 

Laboratory studies indicate that aquathermolysis can be used to aid in the remediation of waste oils, chromium (Cr VI) and volatile organic compounds (VOCs) in contaminated soils and aquifers. Aquathermolysis is particularly useful in lowering the viscosity of oil and increasing its mobility to facilitate further treatment. Potential applications range from treating household and industrial refuse to destruction of chemical warfare agents. 

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. 

Bio-Electrics, Incorporated, has developed the Electrofrac Detoxification System to treat hazardous contaminants in soil. The system, which was developed from gasification research, uses electrodes placed in soil to heat the site. There are potential applications of this technology for removal of volatile organic compounds (VOCs), pyrolysis of non-VOCs, treatment of organic residues, and in situ vitrification of soils and asbestos. There have been bench-scale tests of the technology for remediation applications. 

E rovides for complete site cleanup by addressing less volatile contaminants as well as volatile organic compounds (VOCs)... 

Catalytic oxidation is capable of treating contaminant concentrations ranging from 1 part per million (ppm) to 20,000 ppm. Typically, it is applied to streams containing about 3000 ppm per volume or less of volatile organic compounds (VOCs). At levels approaching 3000 ppm per volume VOCs, the recoverable heat from the process may be sufficient to sustain oxidation without additional fuel. 

This technology can treat materials contaminated with a wide range of organic contaminants, including solvents, volatile organic compounds (VOCs), and semivolatile organic compounds (SVOCs). CFBC is particularly suited for the treatment of media contaminated with polychlorinated biphenyls (PCBs). 

According to the developer, the process is capable of treating waste such as oilfield reserve pits, lagoon waste, hazardous waste (e.g., medical, etc.), municipal waste, contaminated soil, and volatile organic compounds (VOCs), and general port or terminal waste. 

The two-phase vacuum extraction (TPVE) technology allows for the in situ remediation of soils and groundwater contaminated with volatile organic compounds (VOCs). Two-phase vacuum extraction is similar to conventional vapor extraction in the equipment required, with the exception that it is designed to actively remove contaminated groundwater from the extraction well along with the vapor-phase contamination. 

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,... 

CESAR was developed to address the problem of locating, characterizing, and removing dense non-aqueous-phase liquids (DNAPLs) from contaminated aquifer systems. The process is particularly suited to remediating groundwater contaminated with chlorinated solvents, such as trichloroethylene (TCE), tetrachloroethene (PCE), trichloroethane (TCE), and carbon tetrachloride (CCE). According to the vendor, CESAR can also be applied to sites contaminated with creosote, polychlorinated biphenyls (PCBs), Freon 113, volatile organic compounds (VOCs),... 

VESTRIP is a system designed for the in situ treatment of soils contaminated with volatile organic compounds (VOCs) benzene, toluene, ethylbenzene, and xylenes (BTEX) and other contaminants that are amenable to soil vapor extraction (SVE). The vendor, Ejector Systems, Inc. (ESI) has combined the key components of SVE systems with an air stripper to form a product that performs the functions of both. The name, VESTRIP, is a contraction of VES (vapor extraction system) and air stripping. 

The Stripperator is an ex situ technology for the treatment of hydrocarbon-contaminated ground-water. It integrates an oil/water separator, an air stripper, a sump, and a blower into one unit. According to the vendor, the technology will separate free product, coalesce suspended or colloidal hydrocarbons, settle solids, and remove 99.99% of dissolved volatile organic compounds (VOCs). 

TCE-degrading bacteria is a patented technology for the treatment of soil, groundwater and wastewater contaminated with trichloroethylene (TCE). The particular strain of bacteria used in this technology does not require the addition of a toxic co-substrate to activate the bacterial destruction of TCE. The technology can be used to remediate virtually any media type contaminated with one or more volatile organic compounds (VOCs), including TCE, and can be used for in situ or ex situ bioremediation. 

Enviro-Klean Technologies Inc s (EKTI) KLEAN-MACHINE is a patented ex situ, low-temperature thermal desorption technology used to treat petroleum-contaminated soils. The KLEAN-MACHINE treats soil contaminated with hydrocarbons, volatile organic compounds (VOCs), and petroleum hydrocarbons (with a carbon chain length of 45 carbons or less). The technology also cleans baghouse fines. 

Reclaim is a passive, in situ technology that uses a hydrophobic porous polymer to attract, adsorb, and concentrate petroleum hydrocarbons and volatile organic compounds (VOCs) from soils and/or groundwater. Reclaim is considered a passive treatment technology because it requires no mechanical equipment remediation consists of placing polymer-filled canisters in recovery wells and allowing the containers to attract and adsorb organic contaminants. Reclaim canisters are then recycled and contaminants recovered for analysis and/or disposal. This polymer extracts contaminants whether they are in liquid phase, vapor phase or dissolved phase in water. 

EnviroSep, Inc. (EnviroSep), has developed a thick-film absorption technology for the removal of volatile organic compounds (VOCs) from water. The technology uses a proprietary form of silicone rubber to absorb contaminants. The vendor claims the technology is effective for VOCs with less than 2% solubility in water and a boiling point of less than 200°C for the pure compound and is most efficient for use at sites with contaminant concentrations between 10 parts per million (ppm) and 2000 ppm. The technology is intended for aqueous waste streams. 

The liquid waste must be pumpable. Contaminants must be in particulate form, or it must be possible to precipitate dissolved contaminants such as metal ions chemically. Separation must provide an advantage. The EPOC microfiltration technology does not remove volatile organic compounds (VOCs) from liquids. The unit s operation is affected by cold weather. 

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