Aerobic cometabolic degradation of chloroform with butane: Influence of system features on biomass adaptation

ABSTRACT: The adaptation to butane and chloroform (CF) was studied in 24 microcosms containing different aquifer materials and operated under different experimental conditions. Two real-case scenarios were simulated in order to perform a preliminary evaluation of the feasibility of the in situ and on-site cometabolic remediation of CF-polluted sites utilizing butane as the growth substrate. The study was conducted by measuring the time necessary for the beginning of butane and CF consumption (lag-time) and the biodegradation rates of butane and CF; microcosm augmentation with microorganisms obtained from a CF-degrading microcosm was also evaluated. In all the microcosms simulating the two real-case scenarios a 4.3 days lag-time for butane consumption was averagely observed, while the degradation of CF began immediately upon spiking or shortly after the onset of butane utilization and proceeded up to complete depletion of the contaminant. Butane consumption rates in the 5 40 mg L-1d-1 range and CF biodegradation rates in the 0.1 8 mg L-1d-1 range were observed during the respective initial spikes. High concentrations of CF (up to 14 mg/L) were biodegraded with no evidence of CF inhibition effects. Bioaugmentation was effective in the microcosms in which the adaptation to CF had proved difficult. The long-term (160 d) degradation of CF was monitored in 3 microcosms, and resulted in a marked increase in CF depletion rates.