Dark fermentation, anaerobic digestion and microbial fuel cells : an integrated system to valorize swine manure and rice bran

This work describes how dark fermentation (DF), anaerobic digestion (AD) and microbial fuel cells (MFC) and solid-liquid separation can be integrated to co-produce valuable biochemicals (hydrogen and methane), bioelectricity and biofertilizers. Two integrated systems (System 1: AD\ua0+\ua0MFC, and System 2: DF\ua0+\ua0AD\ua0+\ua0MFC) are described and compared to a traditional one-stage AD system in converting a mixture (COD\ua0=\ua0124\ua0\ub1\ua08.1\ua0gO2\ua0kg 121Fresh Matter) of swine manure and rice bran. System 1 gave a biomethane yield of 182 LCH4\ua0kg 121COD-added, while System 2 gave L yields of bio-hydrogen and bio-methane of 27.3\ua0\ub1\ua07.2\ua0LH2\ua0kg 121COD-added and 154\ua0\ub1\ua014\ua0LCH4\ua0kg 121COD-added, respectively. A solid-liquid separation (SLS) step was applied to the digested slurry, giving solid and liquid fractions. The liquid fraction was treated via the MFC-steps, showing power densities of 12\u201313\ua0W\ua0m 123 (500\ua0\u3a9) and average bioelectricity yields of 39.8\ua0W\ua0h\ua0kg 121COD to 54.2\ua0W\ua0h\ua0kg 121COD