Autotrophic biocathode for high efficient sulfate reduction in microbial electrolysis cells.

Area of Science:

• Environmental Engineering
• Environmental Microbiology
• Electrochemistry

Background:

• Sulfate contamination in wastewater poses environmental risks.
• Conventional sulfate removal methods can be energy-intensive or produce harmful byproducts.
• Microbial electrolysis cells (MECs) offer a potential bio-electrochemical solution for wastewater treatment.

Purpose of the Study:

• To investigate the efficacy of biocathode microbial electrolysis cells (MECs) for sulfate removal from wastewater.
• To compare the performance of MECs in fed-batch and continuous flow modes.
• To determine the optimal cathode potential for sulfate reduction in MECs.

Main Methods:

• Utilized a two-chambered biocathode microbial electrolysis cell (MEC).
• Conducted experiments in both fed-batch and continuous flow modes.
• Varied cathode potentials from -0.6 to -1.0 V to assess their impact on sulfate removal and electron recovery.

Main Results:

• Fed-batch operation achieved an average sulfate reduction rate of 0.49 mg/d, with sulfide increasing to 3.1 ± 0.7 mg/L.
• Continuous flow mode demonstrated a 49% higher sulfate removal rate and an 11-fold increase in electron production rate compared to fed-batch mode.
• Maximum electron recovery efficiency of 50% was observed at -0.8 V, while the highest sulfate removal efficiency of (39 ± 9.2)% was achieved at -0.9 V.

Conclusions:

• Biocathode MECs are a viable technology for efficient sulfate removal from wastewater.
• Continuous flow operation significantly enhances MEC performance for sulfate reduction.
• Optimized cathode potentials are crucial for maximizing sulfate removal efficiency and electron recovery in MECs for wastewater treatment.