Volatile organic compounds aeration

Aeration basins are wastewater ponds or lagoons that have air introduced by mechanical action. Aeration may be performed to assist aerobic bioremediation and/or to remove volatile organic compounds. In an aeration basin, oxygen is usually supplied by surface aerators or by diffused aeration units. The action of the aerators and that of the rising air bubbles from the diffuser is used to keep the contents of the basin in suspension. Aeration is widely used in wastewater treatment and can be adapted to treat groundwater. 

Biovault is a commercially available, nonproprietary, ex situ treatment for soil and sediment contaminated with chlorinated and nonchlorinated volatile organic compounds (CVOCs and VOCs). The basic biovault process is to promote the degradation of the existing soil contaminants in consolidated piles by stimulation of the indigenous (or augmented) microbial population. The process typically includes low-intensity aeration, moisture control, and supplementation with nutrients. 

The low-temperature thermal aeration (ETTA) technology is a thermal desorption process that separates chlorinated hydrocarbons, volatile organic compounds (VOCs), semivolatile organic compounds (S VOCs), pesticides, and petroleum hydrocarbons from soils at temperatures of 300 to 800° F. This technology uses hot air to desorb contaminants from soil into a contained airstream and treats the airstream before discharging it to the atmosphere. The system is transportable and consists of six major components assembled on flat-bed trailers. The entire system and support areas require approximately 10,000 ft of operating space. 

Aeration is often employed to strip volatile organic compounds from water and is favored by large HA values. Conversely, volatilization must be controlled or contained in many bioremediation processes. Henry s Law constant is highly temperature sensitive, and temperature changes of 10 °C can give threefold increases in HA. 

Gas-to-liquid mass transfer is a transport phenomenon that involves the transfer of a component (or multiple components) between gas and liquid phases. Gas-liquid contactors, such as gas-liquid absorption/ stripping columns, gas-liquid-solid fluidized beds, airlift reactors, gas bubble reactors, and trickle-bed reactors (TBRs) are frequently encountered in chemical industry. Gas-to-liquid mass transfer is also applied in environmental control systems, e.g., aeration in wastewater treatment where oxygen is transferred from air to water, trickle-bed filters, and scrubbers for the removal of volatile organic compounds. In addition, gas-to-liquid mass transfer is an important factor in gas-liquid emulsion polymerization, and the rate of polymerization could, thus, be enhanced significantly by mechanical agitation. 

The US EPA has identified many types of organic compounds in our water supplies. Some of the organic compounds are volatile, and, as a result, aeration would be a good process selection for removing them from water. For compounds that are non-volatile, adsorption would be a better process selection than aeration for their removal from the water. Some common volatiles include trihalomethanes, which have already been discussed chlorobenzene, 1,1,1-trichloroethane, tetrachloroethylene, and trichloroethylene. Aeration can achieve up to 95% removal of these compounds. 

Aeration an effective technique for removal of volatile organic compoimds or gasoline-impacted soils, in warmer cUmates. The process is simple - the soils are exposed to the air through excavation and handling activities, and then further exposed by being processed through a powder screen. The volatile compounds are released from the soil into the atmosphere. 

PROBABLE FATE photolysis photooxidation definitely occurs, photooxidation half-life in water 3.2-160 days photooxidation half-life in air 1.19-11.9 hrs oxidation metal-catalyzed oxidation occurs in aerated surface waters, oxidation by peroxy radicals is important, photochemically produced hydroxyl radicals degrades compound in daylight hours, half-life 8 hrs hydrolysis not an important process volatilization not an important process sorption slight potential for adsorption onto organic materials, adsorption to sediment will be moderate biological processes biodegradation can occur other reactions/interactions chlorine present in water could chlorinate the eompound can be washed out by rain... 

The presence of other oxidizing agents such as manganese(IV) can interfere with the chlorine determination if the titration is performed at pH<3.5. Under this condition, the organic chloramines are often converted to either monochloramine or dichloramine, resulting in positive errors for these substances. Also, the volatilization of chlorine compounds can result in low recoveries. This can occur due to the violent agitation or aeration of some of the chloramines prior to the addition of iodide. 

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