Pilot-scale bioelectrochemical system for efficient conversion of 4-chloronitrobenzene

Area of Science:

• Environmental Science
• Environmental Engineering
• Electrochemistry

Background:

• 4-Chloronitrobenzene (4-CNB) is a highly toxic environmental contaminant.
• Conventional removal methods for 4-CNB are often inefficient, costly, and unsustainable.
• Developing effective and sustainable remediation strategies for 4-CNB is crucial for ecological health.

Purpose of the Study:

• To develop and evaluate a pilot-scale bioelectrochemical system (BES) for the transformation of 4-CNB.
• To investigate the impact of operational parameters like influent concentration and hydraulic retention time (HRT) on BES performance.
• To compare the efficiency of the BES with conventional anaerobic processes for 4-CNB removal.

Main Methods:

• A pilot-scale BES with an effective volume of 18 L was constructed and operated continuously.
• The system was subjected to varying influent 4-CNB concentrations and hydraulic retention times (HRTs).
• The bioelectrochemical transformation of 4-CNB to 4-chloroaniline (4-CAN) was monitored, with external voltage applied to the cathode.

Main Results:

• The BES demonstrated significant 4-CNB reduction and 4-CAN formation under continuous operation.
• Initial 4-CNB concentration and HRT significantly influenced the reduction and formation efficiencies.
• At 0.4 V and 48 h HRT, 4-CNB reduction reached 99% and 4-CAN formation reached 94.1%.
• The powered BES outperformed conventional anaerobic processes in 4-CNB conversion efficiency.

Conclusions:

• The pilot-scale BES is effective for converting toxic 4-CNB to less toxic 4-CAN.
• The application of a small external voltage enhances microbial-mediated electron transfer for efficient 4-CNB transformation.
• This study presents a sustainable and economical strategy for 4-CNB elimination in wastewater treatment.