High-Rate Bioelectrochemical Anaerobic Digester for Biomethane Production from Food Waste.

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Anaerobic digestion is a key process for waste treatment and biogas production.
• Enhancing anaerobic digestion with bioelectrochemical systems can improve efficiency and stability.
• Food waste represents a significant, underutilized resource for biogas generation.

Purpose of the Study:

• To compare the methane production and stability of a bioelectrochemically enhanced anaerobic digester (BEAD) with a conventional Anaerobic Upflow Sludge Bed (UASB) reactor.
• To evaluate the performance of BEAD reactors using food waste leachate and liquid fraction of food waste under different operational conditions.
• To assess the energy consumption of bioelectrochemical methane production.

Main Methods:

• Operated BEAD and UASB reactors under controlled temperatures (22°C and 35°C) and organic loading rates (3-8 g L^-1 d^-1).
• Utilized food waste leachate and liquid fraction of food waste as feedstocks.
• Employed 3-dimensional flow-through electrodes made of conductive polypropylene biorings in the BEAD reactor.

Main Results:

• BEAD reactors achieved up to 30% higher methane (CH₄) yield (0.35-0.38 L g^-1 COD consumed) compared to UASB reactors.
• BEAD reactors demonstrated improved stability under organic overload conditions, especially at loads above 6 g L^-1 d^-1.
• Energy consumption for bioelectrochemical methane production was estimated at 5.1-12.4 Wh L^-1 CH₄, which is significantly lower than H₂-based methanation.

Conclusions:

• BEAD technology significantly increases methane production and enhances process stability in anaerobic digestion.
• BEAD offers a novel and sustainable approach for efficient waste management and biogas recovery.
• The findings support the potential of bioelectrochemical systems for optimizing anaerobic digestion processes.