Reductive dechlorination of tetrachloroethene by two compost samples with different maturity

Area of Science:

• Environmental Science
• Microbiology
• Bioremediation

Background:

• Tetrachloroethene (PCE) is a persistent environmental pollutant.
• Bioremediation using microbial processes offers a sustainable solution for PCE removal.

Purpose of the Study:

• To evaluate the efficacy of compost microcosms for reductive dechlorination of PCE.
• To identify factors influencing PCE degradation rates and pathways.

Main Methods:

• Microcosm experiments using bagasse/manure and yard-trimming compost at varying maturity levels.
• Monitoring of PCE and ethene concentrations over 180 days.
• Investigation of factors including initial PCE concentration, dissolved oxygen, pH, redox potential, and microbial activity using inhibitors.

Main Results:

• Less mature compost samples effectively dechlorinated 300 μM of PCE to ethene within 180 days.
• Reduced initial PCE concentration and anaerobic conditions (low dissolved oxygen) enhanced dechlorination efficiency.
• Ethene production correlated with redox potential dropping below -150 mV, with near-neutral pH maintained.

Conclusions:

• Compost, owing to its high carbon content, microbial diversity, and buffering capacity, is a promising medium for PCE bioremediation.
• Optimizing conditions like reduced oxygen and PCE levels can significantly improve reductive dechlorination rates.