Bench-scale column experiments to study the containment of Cr(VI) in confined aquifers by bio-transformation.
Bench-scale soil column experiments were conducted to study the effectiveness of Cr(VI) containment in confined aquifers using in situ bio-transformation. Batch adsorption studies were carried out to estimate the adsorption capacities of two different soils for Cr(VI) and Cr(III). Bio-kinetic parameters were evaluated for the enriched microbial system. The inhibition constant, evaluated using Monod's inhibition model, was found to be 11.46 mg/L of Cr(VI). Transport studies indicated that it would not be possible to contain Cr(VI) by adsorption alone. Transport and bio-transformation studies indicated that the pore velocity and the initial bio-mass concentration significantly affect the containment process. In situ bio-remediation is effective in the case of silty aquifers. Cr(VI) concentration of 25 mg/L was effectively contained within 60 cm of a confined silty aquifer. Cr(VI) containment could be achieved in sandy aquifers when the pore velocity was very low and the initial augmented bio-mass was high. A bio-barrier of approximately one meter width would be able to contain Cr(VI) if the initial Cr(VI) concentration is as much as 25 mg/L.
Shashidhar
T
T
Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.
Philip
Ligy
L
Murty Bhallamudi
S
S
D000327:Adsorption; D001673:Biodegradation, Environmental; D002274:Carcinogens, Environmental / Q000302:isolation & purification*; D002857:Chromium / Q000302:isolation & purification*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000302:isolation & purification*; D014881:Water Supply
D002274:Carcinogens, Environmental; D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion