A novel twin microbial fuel cell powered electro-Fenton system (twin-MFCⓅEFs) for waste activated sludge treatment: reduction, stabilization, and resource utilization

Appropriate management and treatment of waste activated sludge (WAS) for reduction, stabilization, and resource utilization are critical components of effective pollution control strategies. The microbial fuel cell powered electro-Fenton system (MFCⓅEFs) has been increasingly recognized as a promising strategy for sludge treatment. However, the complex structural properties of sludge result in the rate-limiting step of anodic hydrolysis and low degradation of cathodic treatment. Therefore, a novel twin-MFCⓅEFs, which performs coupling and mutual feedback of reactive oxygen components and microbial metabolism, was constructed to regulate sludge characteristic variations. The treated sludge exhibited improved dewaterability from 83.21 % to 65.18 % of water content of sludge cake. Lower aromatic compounds (C[dbnd]C and C[dbnd]O double bonds), tryptophan proteins, and humic acid-like organics in extracellular polymeric substances facilitated sludge-water separation. The system achieved a high level of sludge degradation, with a total chemical oxygen demand and volatile substances of 59.85 % and 67.59 % reduction, respectively. Decreased α-helix ratio and non-protonated nitrogen in amides and amines indicated the destruction of proteins to looser structures and simpler forms. The twin-MFCⓅEFs outperformed MFCⓅEFs in electricity generation by 2.75 times with a significantly higher maximum power density (5.85 mV/m³), decreased anode equilibrium potential, and enhanced transfer coefficient. The biofilms were more conducive to organic matter degradation with a higher abundance of Chloroflexi, Firmicutes, and carbohydrate metabolism functional genes. The twin-MFCⓅEFs can simultaneously improve dewaterability, degradation efficiency, and electricity generation capacity with low energy consumption, high efficiency, safety, and stability.