Coupling the electrocatalytic dechlorination of 2,4-D with electroactive microbial anodes

Area of Science:

• Environmental Science
• Electrochemistry
• Microbiology

Background:

• 2,4-D is a widely used herbicide, posing environmental risks due to its persistence.
• Conventional methods for 2,4-D removal can be energy-intensive and less effective.
• Microbial electrochemical systems (MES) offer a potential sustainable solution for pollutant degradation.

Purpose of the Study:

• To investigate the feasibility of dechlorinating 2,4-D using MES.
• To compare the efficiency of microbial fuel cell (MFC) and microbial electrolysis cell (MEC) modes for 2,4-D removal.
• To assess the impact of MES treatment on wastewater biodegradability and energy consumption.

Main Methods:

• Utilized microbial electrochemical systems (MES) operating in both MFC and MEC modes.
• Anodic microbial electrooxidation of sodium acetate drove cathodic electrocatalysis for 2,4-D dechlorination.
• Monitored dechlorination efficiency, BOD/COD ratio for biodegradability, and energy consumption.

Main Results:

• Achieved 32% dechlorination in 72 hours under MFC mode.
• Enhanced dechlorination to 79% under MEC mode (0.6 V external voltage).
• Improved wastewater biodegradability from negative values to 0.135 (MFC) and 0.453 (MEC).

Conclusions:

• MES are a feasible technology for effective 2,4-D dechlorination.
• MEC mode significantly outperforms MFC mode in terms of removal efficiency and biodegradability.
• The MES approach presents a favorable energy balance, with MFC co-generating energy and MEC operation being competitive with other electrochemical methods.