Copper reduction in a pilot-scale membrane-free bioelectrochemical reactor

Area of Science:

• Environmental Science
• Electrochemistry
• Biotechnology

Background:

• Wastewater contamination with heavy metals like copper poses significant environmental risks.
• Conventional methods for copper removal can be energy-intensive and generate secondary waste.
• Bioelectrochemical systems (BES) offer a promising alternative for simultaneous pollutant removal and resource recovery.

Purpose of the Study:

• To evaluate the efficacy of a pilot-scale, membrane-free bioelectrochemical system (BES) for copper removal and recovery.
• To investigate the influence of cathode-anode distance on system performance.
• To analyze the relationship between operational parameters and copper deposition.

Main Methods:

• A 16L membrane-free BES reactor with five cathodes at varying distances from the anode was employed.
• Copper sulfate (CuSO4) solution served as the catholyte, with anaerobic microorganisms as the anodic biocatalyst.
• Cu(II) reduction and recovery as solid-state copper deposits on cathodes were monitored.
• System performance was assessed based on removal efficiency, electric quantities, cathodic efficiencies, and internal resistance.

Main Results:

• High copper removal efficiencies of 92% (over 480 h) and 48% (over 672 h) were achieved with initial Cu2+ concentrations of 600 and 2000 mg, respectively.
• Reduction reaction rate was dependent on initial Cu2+ concentration.
• Decreased cathode-anode distance led to reduced internal resistance and increased voltage output.
• The mass of deposited copper crystals and Cu(I) compounds correlated with current intensity.

Conclusions:

• The membrane-free BES is effective for removing and recovering copper from wastewater.
• Cathode-anode configuration significantly impacts BES performance, influencing voltage and resistance.
• The study highlights the potential of BES technology for sustainable copper management in industrial effluents.