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Heavy Metal Contamination in Groundwater and Potential Remediation Technologies
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Yung Shen Lee, Peck Kah Yeow, Tony Hadibarata, Mohamed Soliman Elshikh
Due to the limitations of the pump and treat method to remediate sources of groundwater contaminations, in situ air sparging (ISAS) has gained popularity due to its easy implementation and economical standings. Air sparging involves the injection of clean pressurized gas into the contaminated zone to treat and mitigate contaminant plumes. Unlike biosparging, its primary function is to increase the amount of oxygen content inside the soils, which in turn, allows aerobic biodegradation. Unfortunately, large areas with contaminations may be deemed ineffective in sparging due to its limited radius of sparging effectiveness. Apart from that, the incorrect air injection pressure could result in the mobilization of free nonaqueous-phase liquid contaminants to other uncontaminated areas (Mohamed et al. 2007, Wang et al. 2007).
Voltammetry
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Mark P. Olson, William R. LaCourse
Although it is not required, an electrochemical cell may also be fitted with a sparging line and/or stirring apparatus. Sparging is a process whereby an inert gas such as N2 or He is bubbled into the solution in the electrochemical cell to remove dissolved O2. This is done because dissolved O2 can be reduced and sometimes interferes with analyte response. The solution may also be stirred to study the response of analyte under forced convection. This comes under the heading of hydrodynamic voltammetry. Hydrodynamic conditions may be used to simulate the response of an analyte in flowing systems. Two common methods may be used to generate hydrodynamic conditions. The first is simply to stir externally by adding a magnetic stir bar to the solution and stirring at a fixed rate. The second is to use a rotating disk electrode (RDE). The use of an RDE is advantageous over external stirring, since it allows more precise control over hydrodynamics. Hydrodynamic voltammetry will be discussed in more detail in a later section.
Air Stripping and Soil Vapor Extraction as Site Remediation Measures
Published in Donald L. Wise, Debra J. Trantolo, Edward J. Cichon, Hilary I. Inyang, Ulrich Stottmeister, Remediation Engineering of Contaminated Soils, 2000
Constantine J. Gregory, Frederic C. Blanc
Air sparging is an in-situ technology used to remediate contaminated groundwater and soil. Sparging involves agitation of a liquid by blowing air through it. In the case of site remediation, the liquid is in the saturated subsoil below the groundwater table. If it remains in the gas bubble form this is induced air will accumulate and drive VOCs to the vadose zone, where SVE techniques can be used to collect the vapors if required. Air sparging is also used in some cases to provide oxygen required for in-situ bioremediation of soils. The process is applicable to high-permeability, large-grain-sized soils.
Thermal-Hydraulic and Neutronic Phenomena Important in Modeling and Simulation of Liquid-Fuel Molten Salt Reactors
Published in Nuclear Technology, 2020
Nicholas R. Brown, David J. Diamond, Stephen Bajorek, Richard Denning
Generation of gas via transmutation, radiolysis, chemical reaction, or entrainment of a cover gas could lead to the need to model gas transport through the primary system. The presence of gas impacts many physical properties. To understand how that gas presents itself requires understanding the separation of fission gases from the liquid and the entrainment of a cover gas at the surface of the liquid. Depending on the design of the system, pumps in designs using a cover gas could also be a source of entrained bubbles. Sparging, which may be useful in removing contaminants through injection of helium or other inert gas, would result in voids that would need to be simulated due to their effect on reactivity. Tritium and any gas produced by radiolysis would be important considerations if produced in quantities sufficient to generate voids in the primary coolant.