Response of chlorinated hydrocarbon transformation and microbial community structure in an aquifer to joint H 2 and O 2 .

Hydrogen (H 2 ) and oxygen (O 2 ) are critical electron donors and acceptors to promote the anaerobic and aerobic microbial transformation of chlorinated hydrocarbons (CHCs), respectively. Electrochemical technology can effectively supply H 2 and O 2 directly to an aquifer. However, the response of CHC transformation and microbial community structure to joint H 2 and O 2 are still unclear. In this work, microcosms containing different combinations of H 2 and O 2 were constructed with natural sediments and nine mixed CHCs. The joint H 2 and O 2 microcosm (H 2 /O 2 microcosm) significantly promoted the biotransformation of trichloroethylene (TCE), trans -dichloroethene ( t DCE) and chloroform (CF). Illumina sequencing analyses suggested that a particular microbial community was formed in the H 2 /O 2 microcosm. The specific microbial species included Methyloversatilis , Dechloromonas , Sediminibacterium , Pseudomonas , Acinetobacter , Curvibacter , Comamonas and Acidovorax , and the relative abundance of the tceA , phe and soxB genes synchronously increased. These results suggested that some specific microbes are potential CHC converters using H 2 and O 2 as energy sources, and aerobic and anaerobic transformations exist simultaneously in the H 2 /O 2 microcosm. It provides a theoretical basis for establishing efficient green remediation technologies for CHC contaminated aquifers.