Use of calcium peroxide to provide oxygen for contaminant biodegradation in a saturated soil.
Laboratory studies were conducted in solid-phase reactors on a silty loam contaminated with bis-(2-ethylhexyl) phthalate (BEHP) to determine the conditions under which calcium peroxide (CaO(2)) would promote the aerobic bioremediation of water-saturated soil. Closed 500 ml solid-phase reactors were operated to determine whether CaO(2) stimulated the biodegradation of BEHP in saturated soil. Ex situ bioremediation conditions were then simulated by mixing water-saturated soil for 6 h before placing the soil in three vented, 2 l solid-phase reactors for 50 days. Biodegradation of BEHP was quantified using four different measurements of microbial activity: (1) oxygen concentrations in the reactor gas; (2) bacterial colony-forming units (CFU); (3) fungal CFU; and (4) 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride dehydrogenase activity (INT-DHA). CaO(2) released molecular O(2), which retarded dewatering but substantially enhanced BEHP biodegradation. After 20 days, BEHP in the amended reactor was reduced from 20.3 to roughly 5 g kg(-1) vs. 15 g kg(-1) in the reactor without CaO(2). Bacterial growth was favored over fungal growth at elevated moisture and BEHP levels.
Cassidy
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DP
Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008, USA. daniel.cassidy@wmich.edu
Irvine
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RL
D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D017610:Calcium Compounds / Q000737:chemistry; D004787:Environmental Pollution / Q000517:prevention & control; D005658:Fungi / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010545:Peroxides / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
D017610:Calcium Compounds; D010545:Peroxides; D012989:Soil Pollutants; D010100:Oxygen