Aquifer sparging

Aquifer bioremediation, defined, 3 758t Aquifer flow, 12 842 Aquifers, 12 838-839 Aquifer sparging, defined, 3 758t AraA [9-(P-D-arabinofuranosyl)-9H-purin-6-amine], 4 713 Arabidopsis, molecular genetics of cellulose biosynthesis, 5 366 Arabinanase, 10 300 Arabinans, classification by structure, 4 723t... 

In the case of pure oxygen sparging, the rate of oxygen supply in the aquifer will be... 

Johnston, C.D., Rayner, J.L. and Briegel, D., Effectiveness of in situ air sparging for removing NAPL gasoline from a sandy aquifer near Perth, Western Australia, J. Contam. Hydrol., 59, 87-111, 2002. 

Since 1995, the sparks solvent/fuel site located in Sparks, Nevada, a remediation system consisting of MPE, air sparging, and SVE, has been operational. The treatment system consists of 29 MPE wells, an oil-water separator, and a fluidized bed bioreactor, with an influent flow rate of 23.3 L/s (370 gpm) and a retention time of 8 min. Vapors are sent through a condenser, followed by a thermal oxidizer, before its release to the atmosphere. Condensate is sent back through the oil-water separator. Performance data, available for the first 650 days of site operation, showed a reduction in MTBE concentration across the bioreactor from 2400 to 55 pg/L. No data were provided for reduction of MTBE concentrations in the aquifer.51... 

Aerobic treatment of aquifer oxygen is usually supphed by one of three methods direct air sparging of air or oxygen into wells screened below the contaminated zone, saturation of water with air or oxygen prior to reinjection, or addition of an oxidant (typically a peroxide compound) directly into an injection well or injection water. Regardless of the mechanism of introduction, the important factor is that the oxidant is distributed throughout the contaminated zone at a concentration and rate such that it can be utilized by the microorganisms. 

Air sparging is usually accomplished by forcing air through a short section of well screen or a porous ceramic block. As the air enters the aquifer, it passes through the soil pores and forms very small bubbles, which increase the transfer of oxygen by diffusion. When properly installed below the aquifer interface, the air is delivered under pressure, which forces it to disperse. Up to 10 ppm DO can be provided. 

Spartech is a mobile system designed for the removal of volatile contaminants from aquifers. It is a patented air sparging system that works by bubbling air through an aquifer and is essentially an in situ method of air stripping. The volatilized contaminants may be recovered by using a soil vapor extraction (SVE) system or similar device. 

The vendor claims that the addition of oxygen during air sparging enhances the aerobic microorganism growth, accelerating breakdown of contaminants in the aquifer. 

A serious disadvantage of air sparging is the so-called gas clogging effect. Nitrogen bubbles remaining after oxygen consumption are known to reduce the water filled porosity thus reducing the permeability of the aquifer in the... 

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