Chloroform aerobic cometabolic biodegradation by Rhodococcus aetherovorans BCP1 in continuous-flow biofilm reactors fed with alternated oxygen and butane pulses

This work focuses on chloroform (CF) cometabolism by a butane-grown aerobic pure culture (Rhodococcus aetherovorans BCP1) in continuous-flow biofilm reactors. The goals were to study CF biodegradation by BCP1 and to evaluate the applicability of the pulsed injection of growth substrate and oxygen in biofilm reactors. The attached-cell tests were initially conducted in a 0.165 L bioreactor and then scaled-up to a 1.772 L bioreactor. Glass cylinders were utilized as biofilm carriers. The continuous supply of growth substrate (butane), which led to the attainment of the highest CF degradation rate (8.2 mg CF / (day m2 biofilm surface)), was compared with 4 schedules of butane and oxygen pulsed feeding. The pulsed injection technique allowed the attainment of a ratio of CF mass degraded per unit mass of butane consumed equal to 0.17 mg CF / mg butane, a value 4 times higher than that obtained with the continuous substrate supply.