Aerobic cometabolic bioremediation of an aquifer polluted by chlorinated solvents: preliminary investigation of the feasibility of a packed bed reactor on-site process

This work focuses on the enrichment of a trichloroethylene (TCE) and 1,1,2,2-tetrachloroethane (TeCA) cometabolizing aerobic microbial consortium from a contaminated site in Northern Italy, for the development of an on-site bioremediation treatment. The goals were: (i) to select the best growth substrate and the best-performing consortium in terms of contaminant degradation capability; (ii) to perform a preliminary suspended-cell kinetic test; (iii) to perform a preliminary evaluation of the feasibility of the co-metabolic treatment of the tested groundwater in a packed-bed reactor operating at the site’s temperature (15°C). The best degradation results were obtained with a butane-growing consortium. At 15° C, the selected culture resulted in short lag-times for the onset of butane utilization (< 1 day) and TCE and TeCA degradation (< 1 - 8 days). Once immobilized on 4 different porous carriers, the selected consortium was able to grow and form a stable biofilm. The TCE and TeCA degradation rates resulted similar for the 4 carriers tested. Further experiments are in progress to estimate the kinetic parameters of the co-metabolic processes and to understand which carrier leads to the best performances in a continuous-flow packed-bed reactor process.