Groundwater aeration

Crume RV, Ryan WM, Peters TA, et al. 1990. Risk analysis on air from groundwater aeration. J Water Poll Control Fed 62 119-123. 

Zeist, Netherlands [83 1 Groundwater Aeration Filtration over CaCOjMgO GAC fixation Removal of trichloroethane Particle size 1 mm Depth of bed 1.5 m Filter diameter 3.3 m Vol. carbon per filter 12 m 0)ntact time 12 min. Empty bed vol until regeneration 25,000 No. filters 3 by 2 Backwash 1st filter only... 

Sorption of plutonium (l.fixlO-11 M) and americium (2xl0-9 M) in artificial groundwater (salt concentration 300 mg/liter total carbonate 120 mg/liter Ref. 59) on some geologic minerals, quartz, biotite, o apatite, o attapulgite, montmorillonite. Dashed lines indicate the range for major minerals in igneous rocks. Experimental conditions room temperature, particle size 0.04-0.06 mm, solid/liquid ratio 6-10 g/1, aerated system, contact time 6 days. 

Simple aeration of groundwater in surface installations cannot meet the demand for oxygen supply in most bioremediation projects. This is illustrated in the following example (adapted from Reference 10). 

Wang, L.K., Wang, P, and Clesceri, N.L., Development of a combined biological aeration and flotation system for groundwater decontamination, Proc. Industrial Waste Conference, Purdue University, West Lafayee, IN, 1993. 

In situ oxygen supply requires aeration wells for the injection of oxygen. The criteria are that the aeration well zone must be wide enough to allow the total plume to pass through, and the flow of air must be sufficient to produce a substantial radius of aeration while small enough so as not to create an air barrier to groundwater flow. The required residence time tr for aeration can be calculated from Darcy s law as a function of the groundwater head and hydraulic conductivity ... 

The course taken by any particular fossilization process is, therefore, determined by the physical and chemical factors prevalent in the environment of the dead remains. The physical factors include temperature, degree of aeration, and rate of flow of groundwater. The nature of minerals and rocks, and of the groundwater at the site of burial, are the most important chemical factors. Reconstructing and explaining the processes undergone by dead remains, from the time of death to when they are fully fossilized, is the concern of taphonomy, the study of the processes taking place when dead remains pass from the biosphere to the lithosphere (see Textbox 69). 

No information concerning the transport and partitioning of 1,2-diphenylhydrazine in the environment was located in the literature. In water, 1,2-diphenylhydrazine is not expected to volatilize because of its rapid oxidation in aerated water (near-surface water) to azobenzene and its low calculated Henry s Law constant (9.42 x 10 atm-m mof) (Lyman et al. 1982). The calculated log Koc (2.76) suggests that 1,2-diphenylhydrazine may sorb to sediments or suspended particles. This is based on the analysis of Kenaga (1980), who stated that chemicals with a K°<= <100 tend to be mobile in soil, while those with a K°<= >L000 tend to sorb. In soil, 1,2-diphenylhydrazine is not expected to leach to groundwater, based on its physical and chemical properties (i.e.. 1,2-diphenylhydrazine reacts rapidly under environmental conditions and, based on its K°c will not rapidly leach downward in the soil column). 

Wickramanayake G, Arther M, Pollack A, et al. 1992. Removal of Aqueous Phase Petroleum Products in Groundwater by Aeration. Battelle Columbus Labs OH. 

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. 

Bioslurping is a commercially available, in situ technology that combines vacuum-enhanced free-product recovery with bioventing of subsurface soils to simultaneously remediate petroleum-hydrocarbon-contaminated groundwater and soils. Vacuum-enhanced recovery utilizes negative pressure to create a partial vacuum that extracts free product and water from the subsurface. Bioventing is forced aeration to accelerate in situ bioremediation of hydrocarbons and non-aqueous-phase liquids (NAPLs). 

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