Pave the way for successful treatment of Nylon wastewater by performance enhancement via unit stacking scale up of dual cathodes up-flow microbial fuel cell and C/N adjustment with urea

Abstract

Integrating filtration membrane cathode and packed granular carbon cathode in an up-flow bio-electrochemical reactor can maintain both higher level treatment capacity and electricity generation in microbial fuel cell (MFC). Further, scale-ups via unit stacking (U-S) or size-enlarged reactor/electrode (SE-RE) were tested treating a Nylon wastewater with inadequate N and high C/N ratio, at suitable hydraulic residence time (HRT). U-S maintained both pollutants removal efficiency and power generation at higher levels than SE-RE, achieving 92.44% NH4+-N, 99.99% NO3--N and 99.66% total inorganic nitrogen removal, and maximum power density 3201 mW/m3 (average 2960 mW/m3). Adjusting influent C/N with urea as additional nitrogen, enhanced COD removal and reduced cathode membrane fouling significantly. The average COD removal reaching 99.28% and 4.23 kg m−3d−1, and average effluent COD concentration and UV254 was 30.37 mg/L and 0.06 cm−1, respectively. The average removals of NH4+-N, NO3--N and total inorganic nitrogen were up to 98.85%, 99.99% and 99.56%, respectively. The EEO (electrical energy at 90% removal) was between 0.48 and 1.40 kWh/m3. U-S scale-up with urea dosage was feasible in practical application of MFC in treating Nylon wastewater.