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Agrochemical Contamination of Soil Recent Technology Innovations for Bioremediation
Published in Amitava Rakshit, Manoj Parihar, Binoy Sarkar, Harikesh B. Singh, Leonardo Fernandes Fraceto, Bioremediation Science From Theory to Practice, 2021
Suryasikha Samal, C.S.K. Mishra
A number of physical and chemical methods are available to remove contaminants from soil. Non biological methods such as low temperature thermal desorption has often been used to remediate pesticide-contaminated sites. This technology involves the removal of organic compounds including pesticides using temperature and volatilization. It requires highly specialized facilities and demands comparatively high cost. Air sparging method is more often used to remove hydrocarbons by injecting large volumes of pressurized air into contaminated soil, removing volatile organic compounds that might otherwise be removed by carbon filtering systems. Another popular method is incineration which is applied to the contaminated soil using heat and oxygen as the oxidizing compounds. Each technology has its advantage as well as limitation for the treatment of specific contaminant (Frazar 2000, Yao et al. 2012).
General Types of Contaminated Site Restoration Methods and Technologies
Published in Kofi Asante-Duah, Management of Contaminated Site Problems, 2019
Air sparging is an in situ remedial technology used to reduce concentrations of volatile constituents that are adsorbed to soils and dissolved in groundwater. It consists of the highly controlled injection of air or oxygen into a contaminant plume in the soil saturated zone. In fact, air sparging is frequently used together with SVE, but it can also be used with other remedial technologies. In the processes involved, air pumped into contaminated groundwater is used to strip volatiles from the groundwater to the soil vadose zone for subsequent capture using SVE. Oxygen present in the air added to the groundwater and vadose zone soils can also enhance the biodegradation of contaminants below and above the water table. Basically, the injected air bubbles traverse horizontally and vertically in channels through the soil column, creating a transient air-filled porosity in which volatilization can occur, that is, by creating an underground stripper that removes volatile and semivolatile organic contaminants by volatilization. Indeed, air sparging effectively creates a crude air stripper in the subsurface, with the soil acting as the packing; the injected air helps to flush the contaminants into the unsaturated zone.
Groundwater Cleanup and Remediation
Published in David H.F. Liu, Béla G. Lipták, Paul A. Bouts, Groundwater and Surface Water Pollution, 2019
David H.F. Liu, Béla G. Lipták, Paul A. Bouts
Air sparging, also called in situ stripping, is an innovative technology that injects air into the saturated zone to remove contaminants from the water. The air injected in the saturated area creates bubbles that rise and carry trapped and dissolved contaminants into the unsaturated zone above the water table (Camp Dresser & McKee, Inc. 1992). This technology is typically used in conjunction with soil vapor extraction (SVE) to enhance the removal rate of contaminants from the saturated and unsaturated zones (Bohler et al. 1990). As volatile organic compounds reach the unsaturated zone, they are captured by the SVE vapor wells that are screened in the unsaturated zone, as illustrated in Figure 5.3.2. Air sparging also provides an oxygen source which may stimulate bioremediation of some contaminants. Air sparging is applicable for contaminants which have a high Henry’s constant or high vapor pressure in soils with high permeability.
Environmental remediation using metals and inorganic and organic materials: a review
Published in Journal of Environmental Science and Health, Part C, 2022
Haragobinda Srichandan, Puneet Kumar Singh, Pankaj Kumar Parhi, Pratikhya Mohanty, Tapan Kumar Adhya, Ritesh Pattnaik, Snehasish Mishra, Pranab Kumar Hota
Thus, remediation of these either at the source or at the catchment is of prime concern. Removal of the contaminants at source is usually done through physical, chemical, physicochemical and biological approaches. Wastewater is primarily physically treated through filtration using screens, sand filtration, membrane filtration, etc., largely to remove suspended materials. Sand filters remove the smaller suspended particulate matter while the dissolved solids would pass through which is subjected to secondary filtration. Membrane filtration that removes suspended and total dissolved solids involves microfiltration, ultrafiltration, reverse osmosis, etc. Similarly, contaminated soil is remediated through various approaches. It may simply be done by replacing the contaminated soil with virgin soil and the contaminant is removed through a slow process of natural healing either in situ or ex situ. Another approach is that the contaminated soil is proportionately mixed with healthy soil to reduce the pollutant concentration to acceptable limit. Another approach to remove the contaminant is vaporization. In order to volatilize the VOCs (volatile organic compounds), air sparging through ground water is resorted to. Flushing of the contaminated soil by groundwater to remove the pollutants is yet another approach.7
A review on groundwater contaminant transport and remediation
Published in ISH Journal of Hydraulic Engineering, 2020
P. K. Sharma, Muskan Mayank, C. S. P. Ojha, S. K. Shukla
The removal of volatile chemicals from groundwater is by using a process known as air sparging. Sparging the groundwater with air and pure oxygen can supply 8–40 mg/L of oxygen depending on the temperature of injection fluid (Lee et al. 1988). Small diameter wells are used to pump air into the aquifer. As the air moves through the aquifer, it evaporates the volatile chemicals (Reddy et al. 1995; Reddy and Adams 2001). Many sites, such as Eaddy Brothers, a gasoline service station located in Hemingway, South Carolina, have been successfully remediated using air sparging (Reddy and Adams 2001).