Increased power generation from primary sludge in microbial fuel cells coupled with prefermentation.

Area of Science:

• Environmental Science
• Biotechnology
• Electrochemistry

Background:

• Wastewater treatment generates significant primary sludge.
• Microbial fuel cells (MFCs) offer a promising method for energy recovery from organic waste.
• Optimizing MFC performance for sludge treatment is crucial for sustainable wastewater management.

Purpose of the Study:

• To evaluate the efficacy of a two-stage process involving prefermentation and MFCs for electricity generation and sludge reduction.
• To compare the performance of MFCs treating raw primary sludge versus prefermentation liquor (PL).
• To analyze the contribution of direct electricity generation versus methane conversion to overall energy production.

Main Methods:

• Single-chambered air-cathode microbial fuel cells (MFCs) were utilized.
• Raw primary sludge and its prefermentation liquor (PL) were used as substrates.
• Electrical output (potential and power density) and sludge reduction (volatile suspended solids) were measured.
• Energy production was analyzed, distinguishing direct electricity generation from methane conversion.

Main Results:

• MFCs treating PL achieved higher maximum potential (0.58 V) and power density (885 mW/m²).
• Direct electricity production from PL was substantially higher (1,921 Wh/kg TCODrem) compared to raw sludge (138 Wh/kg TCODrem).
• The two-stage process demonstrated significant volatile suspended solids reduction (38% for PL vs. 18.3% for raw sludge).

Conclusions:

• A two-stage prefermentation and MFC process is highly beneficial for sludge reduction.
• This integrated approach significantly enhances electricity generation from primary sludge, primarily through methane conversion.
• The findings support the development of sustainable wastewater treatment strategies focused on resource recovery.