Effects of different electron donor feeding patterns on TCE reductive dechlorination performance

Area of Science:

• Environmental Science
• Microbiology
• Geochemistry

Background:

• Enhanced in situ bioremediation is a promising technology for cleaning up contaminated aquifers.
• Trichloroethylene (TCE) is a common groundwater contaminant.
• The efficiency of bioremediation depends on the availability of electron donors and the activity of specific microbial consortia, such as Dehalococcoides spp.

Purpose of the Study:

• To investigate the effect of different feeding patterns of electron donors on the efficiency of enhanced in situ bioremediation of TCE.
• To compare the efficacy of butyrate and hydrogen gas (H2) as electron donors.
• To understand the role of methanogenesis as an electron acceptor process.

Main Methods:

• Laboratory-scale batch experiments were conducted.
• Used butyrate and hydrogen gas (H2) as electron donors.
• Employed a microbial consortium dominated by Dehalococcoides spp. for TCE dechlorination.

Main Results:

• Butyrate demonstrated similar TCE dechlorination efficiency whether injected once or in multiple doses.
• Excessive butyrate addition may indirectly supply necessary H2.
• Methanogenesis was the primary electron accepting process across all experiments.
• Early injection of H2 improved vinyl chloride (VC) to ethene (ETH) dechlorination and suppressed methanogenesis.

Conclusions:

• The feeding pattern of electron donors significantly influences bioremediation efficiency.
• Butyrate is a robust electron donor for TCE bioremediation, less sensitive to feeding strategy.
• Optimizing H2 injection timing is crucial for maximizing dechlorination and minimizing unwanted side reactions like methanogenesis.