Researchers have demonstrated that a water treatment system using microorganisms called membrane biofilm reactor (MBfR) is effective in eliminating the common contaminant chlorinated solvent trichloroethene (TCE) from groundwater.

They took an existing MBfR that was handling perchlorate removal and then introduced TCE into the system.

Rittmann's MBfR works by delivering hydrogen gas to the bacteria through tiny hollow tubes submerged in water. In the right environment, the tubes become coated with a biofilm containing microorganisms. The system provides the microorganisms with hydrogen gas, which must be present for the microorganisms to change the chemical composition of a contaminant and render it harmless.

In the process, the researchers were able to enrich the population of a new type of Dehalococcoides, a special dehalogenating bacteria that can take the hydrogen supplied by the MBfR and reduce TCE all the way to harmless ethene. Using the latest molecular techniques, they could not only identify the bacterial population to handle TCE, but also the genes within these populations that make enzymes that detoxify TCE to ethene.

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