Aerobic bioremediation of aquifers contaminated by chlorinated aliphatic hydrocarbons

Chlorinated aliphatic hydrocarbons (CAHs) are widespread, toxic and recalcitrant subsurface contaminants. Among the different remediation options for CAH-contaminated sites, aerobic bioremediation represents a very interesting one, thanks to the high depletion rates achievable, the possibility to transform several CAHs into non-toxic, easily biodegradable compounds and the limited excavation works required. In most cases, the aerobic bioremediation of a CAH-polluted site can be performed only by means of cometabolism, which requires the supply of a suitable growth substrate. Cometabolic bioremediation is a rather complex process, whose outcome is not predictable on the basis of a mere site characterization: it is therefore necessary to perform a previous feasibility study. In several cases, the biological process can be significantly speeded up by means of the addition of previously selected microbial inocula. Despite the significant progresses made during the last years, the aerobic bioremediation of CAH-contaminated sites is not yet a widespread remediation technology.