Chloroform aerobic cometabolism by butane-utilizing bacteria in bioaugmented and non-bioaugmented soil/groundwater microcosms

The aerobic cometabolic chloroform (CF) degradation by butane-growing biomasses was investigated in slurry microcosms. The lag-time for the onset of butane utilization by the indigenous biomass of the studied sandy soil was less than 2 weeks in all the experimental conditions tested. The shortest lags were obtained in the absence of CF. The lag-time for the onset of CF depletion was strongly affected by temperature, with no CF degradation after several weeks in the tests conducted at 15 °C. Bioaugmentation treatments performed with two types of butane-utilizing inocula led to a marked decrease of the butane lag-time, even at the smallest concentration of augmented bacteria tested (3500 CFU/mL aq. phase). Tests of prolonged CF degradation in the absence of butane were satisfactorily simulated with a Monod-type kinetic model. Estimates of the minimum butane/CF molar ratio required to sustain CF cometabolism varied from 2.0 to 3.1.