Biokinetic modeling of in situ bioremediation of BTX compounds-impact of process variables and scaleup implications.
The impact of three process parameters, i.e. ground water velocity, oxygen-to-BTX mass ratio, and benzene, toluene and xylene (BTX) concentrations on first-order biodegradation kinetics in a pilot-scale in situ bioremediation system was assessed. Generally, first-order biodegradation coefficients decreased with ground water velocity, and increased with hydrogen peroxide dose and BTX concentration. First-order biodegradation rate coefficients for benzene, toluene, and o-xylene varied from 0.3 to 0.81, 0.24 to 0.72, and 0.21 to 0.63 d(-1), respectively. Biomass-specific first-order rate coefficients were insensitive to ground water velocity, and decreased with increasing BTX concentrations. At 10mg/l BTX concentration, the specific first-order coefficients increased with peroxide dose. However, at the 50mg/l BTX concentration and a peroxide dose of 1020 mg/l, a 30-70% reduction in specific first-order biodegradation coefficients was observed. BTX biodegradation kinetics in this pilot-scale system were approximately one-to-two orders of magnitude slower than in soil microcosms and mixed culture bioreactors, and about 200-300% higher than full-scale systems.
Nakhla
George
G
Department. of Chemical and Biochemical Engineering, Faculty of Engineering, University of Western Ontario, London, Ont, Canada N6A 5B9. gnakhla@eng.uwo.ca
D001554:Benzene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D007700:Kinetics; D008962:Models, Theoretical; D012989:Soil Pollutants / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification; D014992:Xylenes / Q000378:metabolism*
D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene; D001554:Benzene