Degradation of phenolic compounds in wastewater using a conical-shaped packed-bed microbial fuel cell in continuous flow with recycling

A unique conical-shaped single-chamber (SC) microbial fuel cell (MFC) set-up was used to demonstrate the feasibility of continuous mode operation with recycling for the enhanced degradation of phenolic compounds in wastewater. Here, 1,2-propanediol/propylene glycol (1-2-PD, a phenolic compound) was used as the model phenolic compound, which is commonly found in pharmaceutical and cosmetic industrial effluents. Different flow rates ( Q = 1, 3, and 5 cc min −1 ) and recycling ratios (RQ = 0.5, 1, 1.5 cc min −1 ) were used to study the effect of recycling on wastewater treatment in the continuous mode. The effects of the 1-2-PD concentration (1000, 5000, and 10 000 ppm) and solution pH (6.23, 7.84, and 8.32) on the efficacy of SCMFC were determined. The maximum voltage generation (∼380 mV), chemical oxygen demand reduction (∼80%), and 1-2-PD degradation (∼84%) were measured at the optimized effluent and with a recycling flowrate of 1 cc min −1 each. The 16s rRNA sequencing confirmed the abundance of Paenibacillus and Pseudomonas genera in the mixed bacterial culture of the effluent. This study emphasizes the necessity of recycling during wastewater treatment in an SCMFC operated in the continuous mode, which may be further useful for designing new types of effluent treatment plants integrated with MFC for efficiently treating industrial wastewater effluent contaminated with organic compounds. A packed-bed SCMFC is used to demonstrate the positive effects of recycling in continuous mode on the degradation of a phenolic compound in wastewater.