Effect of Different Incubation Periods on <i>Bacillus subtilis</i> and <i>Pseudomonas aeruginosa</i> in a Membraneless Microbial Fuel Cell for Simultaneous Chicken Manure Bioremediation and Electricity Generation

Abstract

The need for energy resources is continuously increasing worldwide and raises the need for environmentally benign, low-cost processes for energy generation. Membraneless microbial fuel cell (ML-MFC) has emerged as a promising solution for electricity production. MFCs are bioelectrical devices that harness the metabolism of electrogenic bacteria (EB) for generation of electrical energy. In the present investigation, Bacillus subtilis (BS) and Pseudomonas aeruginosa (PA) were utilized to catalyze transformation of carbon sources in chicken manure as source of renewable energy. The study was carried out by setting the experimental conditions with the ambient temperature (34°C ± 1°C) pH (12), electrode distance (3 cm), initial moisture amount (57% vol/wt) set as constant. Results highlighted BS and PA performance in an ML-MFC system for 7 to 14 days incubation periods. The specific growth recorded 0.0262 g(Lh−1) BS strain and 0.0141 g(Lh−1) PA strain for 7 days and the specific growth 0.0057 g(Lh−1) BS strain and 0.00163 g(Lh−1) PA strain was recorded after 14 days incubation. ML-MFCs were conducted for 14 days incubation period and significant effect of growth of BS and PA were reflected on voltage and power production. Maximum voltage (BS, 0.06 V; PA, 0.043 V) and power density (BS, 391 mW/m2; PA, 591 mW/m2) were recorded after 14 days of incubation. A series of ML-MFC contributed a promising performance for BS, which was 0.05 V and 9.05 mW/m2, compared with PA, which was 0.022 V and 9.05 mW/m2. Moreover, reduction in macronutrients and micronutrients was analyzed through inductively coupled plasma-optical emission spectroscopy (ICP-OES), chemical oxygen demand (COD) removal, and Fourier-transform infrared spectroscopy (FTIR) analysis. Thus, analysis on scanning electron microscope (SEM) and FTIR bands showed that these two strains are compatible for biofilm formation and degradation of the chicken manure into simple bands. The study concluded that BS showed better performance in terms of EB growth (21.7%; 14 days), COD removal (2.1%; 14 days), and power density generation (54.7%; 14 days) as compared with the PA strain.