Application of the growth substrate pulsed feeding technique to a process of chloroform aerobic cometabolism in a continuous-flow sand-filled reactor

A process of chloroform (CF) aerobic cometabolic biodegradation by a butane-growing consortium was studied for 354 days in a 2-m continuous-flow sand-filled reactor. The study was aimed at (a) investigating the oxygen/substrate pulsed injection as a tool to control the clogging of the porous medium, to attain a wide bioreactive zone and to reduce substrate inhibition on CF cometabolism; (b) developing a reliable model of CF cometabolism in porous media. While the continuous supply of butane rapidly led to the clogging of the porous medium due to excessive biomass growth, the testing of six types of oxygen/substrate pulsed feeding led to the identification of a feeding schedule capable to prevent aquifer clogging and to lead to the development of a long bioreactive zone and to satisfactory CF degradation performances. The tested model of aerobic cometabolism allowed a suitable interpretation of the experimental data as long as the ratio of CF degraded to butane consumed was ≤0.27 mgCF mgbutane−1. A long-term 1-D simulation of the best-performing schedule of pulsed oxygen/substrate supply extended to a 30-m aquifer length resulted in a 20-m bioreactive zone and in a 96% CF removal.

► 355-day test of chloroform aerobic cometabolism in a 2-m continuous-flow sand column. ► Pulsed butane/oxygen feed avoids sand clogging and allows good biomass distribution. ► Stable removal of 82% of the supplied chloroform. ► Application of model of aerobic cometabolism in porous media is partially successful. ► Wrong model predictions for high ratios of chloroform degraded to butane consumed.