Effect of lignite activated coke packing on power generation and phenol degradation in microbial fuel cell treating high strength phenolic wastewater

Abstract

Microbial fuel cell (MFC) is commonly used for easily biodegradable substances, yet its application for high strength phenolic wastewater treatment remains a challenge. This study incorporates lignite activated coke (LAC) into MFC to alleviate the inhibition of phenol and facilitate power generation of MFC. The power generation and phenol degradation in both LAC-MFC and control MFC were investigated at phenol concentrations of 500 mg/L, 700 mg/L and 1000 mg/L. The results showed that the maximum power density in LAC-MFC was maintained in the range of 252.3–278.7 mW/m2 when the phenol concentration increased from 500 mg/L to 1000 mg/L, whereas it was decreased from 246.5 mW/m2 to 167.5 mW/m2 in control-MFC. This corresponds to a high phenol removal of 89.4% to 94.5% in LAC-MFC but a significant decrease from 80.7% to 50.8% in control MFC. The inhibition coefficient (Ki) calculated from Haldane inhibition model decreased by 24.3% in LAC-MFC compare with control MFC, suggesting that the stress of high concentrations of phenol on MFC was largely relieved. In addition, the phenol degradation intermediate products of 2-hydroxymuconic semialdehyde, 4-hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid were apparently lower in LAC-MFC than control MFC, indicating that the biodegradation of phenol was enhanced in LAC-MFC. High-throughput sequencing analysis revealed that Pseudomonas, Desulfuromonas, and Hydrogenophaga might be associated with phenol degradation and power generation in LAC-MFC. Because of its effectiveness in alleviating the toxic effects of phenol, LAC packing is a promising MFC technology for high strength phenolic wastewater treatment.