Microbial fuel cells for clogging assessment in constructed wetlands

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Renewable Energy Generation

Background:

• Clogging in horizontal subsurface flow constructed wetlands (HSSF CWs) diminishes system lifespan and treatment efficiency.
• Existing methods for assessing HSSF CW clogging are time-consuming and not suitable for continuous monitoring.

Purpose of the Study:

• To evaluate the potential of microbial fuel cells (MFCs) for continuous clogging assessment in HSSF CWs.

Main Methods:

• Two membrane-less MFC replicates with gravel anodes were operated for five weeks under laboratory conditions.
• MFCs were loaded weekly with accumulated sludge from a pilot HSSF CW, simulating various clogging degrees (0.2 to 5 years).
• Sludge loading rates varied from 20 to 250 kg TS·m⁻³ CW·year⁻¹.

Main Results:

• A negative correlation was observed between the electric charge produced by the MFCs and the accumulated sludge (degree of clogging).
• Electron transference, indicated by electric charge, nearly ceased at a clogging level equivalent to approximately 5 years (10 kg TS·m⁻³ CW).
• MFC performance effectively reflected the simulated clogging levels within the HSSF CW media.

Conclusions:

• HSSF CWs operated as MFCs demonstrate significant potential for real-time, continuous clogging assessment.
• Further research with extended study periods and realistic conditions is recommended to validate these findings.
• This MFC-based approach offers a more efficient alternative to traditional clogging assessment methods.