Growth of chlorinated solvent-degrading consortia in fed-batch bioreactors and development of a double-substrate high-performing microbial inoculum

The long-term growth process of two microbial consortia effective in the aerobic cometabolic biodegradation of a mixture of 6-chlorinated aliphatic hydrocarbons (CAHs), the effectiveness of these consortia as inocula for the bio-augmentation of different types of microcosms and the development of a double-substrate, high-performing consortium is presented. The propane-utilizing consortium generally proved to be the most effective one, being able to biodegrade vinyl chloride, cis- and trans-1,2-dichloroethylene, trichloroethylene, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane at all the CAH concentrations tested (4 μM). Both consortia maintained unaltered CAH degradation capacities over a 300-day growth period in the absence of the CAHs and were effective in inducing the rapid onset of CAH depletion upon inoculation in slurry microcosms set up with five types of aquifer materials. A consortium supplied with both methane and propane combined the best degradation capacities of the two single-substrate consortia, and maintained stable performances for 150 days under slurry conditions. The degree of conversion of the organic Cl to chloride ions was equal to 90 %.