Application and Mechanistic Study of Lactate Regulation and Microbial Immobilization Technology in Sediment Microbial Fuel Cell Systems
Sediment microbial fuel cells (SMFCs) are a green technology for simultaneous polluted sediment remediation and energy recovery, yet their performance is constrained by insufficient anodic microbial activity and low electron transfer efficiency. This study employed lactate addition combined with composite engineered microbial immobilization to synergistically optimize SMFC performance by enhancing microbial stability and carbon source supply. Results showed that lactate, as an easily utilized electron donor, promoted electrochemical activity, achieving a maximum power density of 22.06 mW·m−2 at 6 mmol·L−1, a 194% improvement over the blank group. Immobilization further enhanced electron transfer efficiency, with the highest output voltage (88.75 mV) being 2.09 times that of the non-immobilized group. For pollutant degradation, the 6 mmol·L−1 lactate group achieved TOC and TN removal rates of 29.02% and 28.4%, respectively, outperforming the control (22.41% and 21.42%). However, high lactate concentrations inhibited microbial metabolism, leading to TOC accumulation. 16S rRNA analysis revealed that the anodic microbial community was dominated by Bacillota and Pseudomonadota, both possessing electroactive and pollutant-degrading capabilities, indicating that lactate and immobilization exert a synergistic effect in SMFCs, simultaneously enhancing electricity generation and pollutant removal efficiency.