Enhancing natural attenuation of tetrachloroethene contaminated sites can be achieved by introducing which compound?

• A. Dissolved Oxygen
• B. Hydrogen Release Compounds
• C. Slow Oxygen Release Compounds
• D. None of the Above

Answer: (B)

Enhancing natural attenuation for tetrachloroethene relies on feeding the microbes that perform reductive dechlorination. Those microbes use hydrogen as an electron donor while the PCE acts as the electron acceptor, stepping the contaminant through a sequence (PCE to TCE to DCE to vinyl chloride to ethene). Hydrogen Release Compounds provide a steady, slow release of hydrogen, sustaining these anaerobic conditions and supplying the energy source the dechlorinating bacteria need. This accelerates the breakdown of PCE to non-toxic end products.

Introducing oxygen, whether dissolved or slowly released, disrupts these anaerobic conditions and can inhibit or stall the dechlorinating microbial community, making remediation slower or less effective. That’s why hydrogen-releasing donors are the appropriate choice to boost enhanced natural attenuation in this context.