Treated clinoptilolite-modified graphite felt bioanode microbial fuel cells for power generation and dye decolourisation

One important factor in microbial fuel cells (MFCs) study is the anode. In MFCs, the anode acts as the key component in the generation of bioelectricity and power. Despite the fact that there have been some improvements in the electrochemical performance of MFCs in recent years, their low power generation is still deemed a major drawback. The effects of surface modifications of the anode as biofilm carrier on the performance of MFCs were investigated. This research focused on the role of the novel fabricated anode as support material for the adhesion of bacterial consortium (NAR-2) consisted of Citrobacter sp. A1, Enterobacter sp. L17 and Enterococcus sp. C1 were used in MFCs reactor for the decolourisation of Acid Red 27 (AR27) and the simultaneous generation of electricity. The performance of a modified anode fabricated using surfactant-treated clinoptilolite (S-TC) with common type of carbonbased material, namely treated clinoptilolite-modified graphite felt (TC-MGF) anode was evaluated with different MFCs constructions. Prior to the MFCs experiments, the modification of anode was successfully verified using different spectroscopic and microscopic techniques such as EDX, FESEM, ATR-FTIR and BET analysis. In addition, screening of parameters for the adhesion of bacterial consortium NAR-2 onto TC-MGF anode (NAR-2-bioanode) was accomplished. The newly-developed TCMGF bioanode was implemented in the dual-chamber (H-type) of the MFC. The performance of TC-MGF bioanode was compared to the results obtained using nonmodified graphite felt (BGF) bioanode. Maximum power densities for BGF and TCMGF bioanodes were 458.8 ± 5.0 and 940.3 ± 4.2 mWm-2, respectively. In the following experimental, a small MFC reactor was fabricated with TC-MGF bioanode to compare the performance of the MFC with commonly used fuel cell membranes, Nafion (N-117 and N-115), which were examined along with the N-212 membrane in a single-chamber cubic di-air cathode (S-CCD-AC) design. The power density and columbic efficiency of N-115 membrane (1022.5 mWm-2 - 35.4%) were significantly higher than the values obtained for the N-117 (592 mWm-2 - 15.6%) and N-212 (493 mWm-2 - 12.3%) membranes. A novel MFC reactor with TC-MGF bioanode novel design (Conch shell) using the N-115 membrane having an air-cathode upflow (A-CU) MFC, as a combination of upflow and MFC technologies was used to compare the presence and absence of a membrane design. The A-CUMFC with membrane-less at flow rate 0.6 mL min-1, anode distance of 0.5 cm and a concentration of AR27 at 900 mg L-1, high decolourisation rate (98%) achieved in a 60-day operation, was 40% higher than that of the membrane-MFC. The average maximum power density obtained (1250 mWm-2) using the membrane-less MFC was higher than that of the membrane-MFC (1108 mWm-2) during the 80-day operation with TC-MGF bioanode

Biodegradation of remazol black b by bacterial consortium nar-2

The ability of the bacterial consortium NAR-2 consisting of A1, C1 and L17 to degrade the model azo dye Remazol Black B (RBB) was studied in batch and in continous systems. Continous decolourisation was performed in a borosilicate glass column (12 mm x 20 mm) packed with Surfactant Modified Clinoptilolite immobilised with bacterial consortium NAR-2. In batch studies, 90.79% decolourisation of RBB was achieved under microaerophilic condition within 80 minutes by inoculating 10% (v/v) of bacterial consortium NAR-2 at a 1:1:1 ratio. This was achieved in modified P5 medium pH 7 and incubated at 45°C under microaerophilic condition.In column bioreactor studies, decolourisation was observed at 45° and carried out by varying the flow rates and dye concentrations.Flow rate at 0.2, 0.4, 0.6 ,0.8 AND 1.0 ml/min were tested and dye concentration of 0.1, 0.3, 0.5, 0.7 and 1.0 g/L were used.Almost 95.8% decolourisation of 0.1 g/L RBB was achieved at the flow rate 0.2ml/min. By fixing 0.2 ml/min as default flow rate,varying concentrations of RBB were examined. Above 90% decolourisation was achieved with 0.1, 0.3 and 0.5 g/L RBB but at 0.7 and 1.0 g/L the percentage drop to 36 and 28%, respectively. Decolourisation percentage began to droped at higher dye concentration. Biomass leached out from the column was determined using viable cell count. From both flow rate and dye concentration experiments, it can be seen that C1 cell wash out was the highest as compared to A1 and L17. Analyses of decolourized and biodegradation products of RBB using total aromatic amines (TAA) showed that reduction of RBB resulted in the formation of aromatic amines. Further aerobic degradation for 15 days showed the amines concentration reduced from an initial of 18 mg/L to 2 mg/L following aerobic treatment in batch whereas in column experiment, the amines concentration dropped significantly from 34 mg/L to 11 mg/L

Biodegradation of remazol black b in sequential microaerophilic-aerobic operations by nar-2 bacterial consortium

The ability of the NAR-2 bacterial consortium, consisting of A1, C1, and L17, to degrade the azo dye model, Remazol Black B (RBB), was studied in an upflow packed-bed reactor for continuous sequential micro- aerophilic–aerobic batch operations. Continuous decolourisation was performed in a borosilicate glass col- umn (12 mm 9 20 mm) packed with surfactant-modified clinoptilolite immobilised by the NAR-2 bacterial consor- tium. In column bioreactor studies, decolourisation was observed at 45 ° C and was carried out by varying the flow rates and dye concentrations in a modified P5 medium with pH 7.0 under microaerophilic conditions. A decolourisation of 95.87 % of 0.1 g/L RBB was achieved at a flow rate of 0.2 mL/min under microaerophilic conditions by the immobilised NAR-2 bacterial consortium. An analysis of the decolourised and biodegradation products of the RBB using total aromatic amines showed that a reduction in the RBB resulted in the formation of aromatic amines. On further aerobic degradation for 15 days, the concentration of the amines dropped significantly, from an initial con- centration of 34 to 11 mg/L, following the aerobic batch treatment experiment. The findings of this study showed that SMC can be a support material for bacterial cell immobilisation in a single upflow reactor with intermittent microaerophilic–aerobic operations, and it was found to be suitable and eco-friendly for the degradation of azo dyes

Investigating effect of proton-exchange membrane on new air-cathode single-chamber microbial fuel cell configuration for bioenergy recovery from Azorubine dye degradation

One of the biggest challenges of using single-chamber microbial fuel cells (MFCs) that utilize proton-exchange membrane (PEM) air cathode for bioenergy recovery from recalcitrant organic compounds present in wastewater is mainly attributed to their high internal resistance in the anodic chamber of the single microbial fuel cell (MFC) configurations. The high internal resistance is due to the small surface area of the anode and cathode electrodes following membrane biofouling and pH splitting conditions as well as substrate and oxygen crossover through the membrane pores by diffusion. To address this issue, the fabrication of new PEM air-cathode single-chamber MFC configuration was investigated with inner channel flow open assembled with double PEM air cathodes (two oxygen reduction activity zones) coupled with spiral-anode MFC (2MA-CsS-AMFC). The effect of various proton-exchange membranes (PEMs), including Nafion 117 (N-117), Nafion 115 (N-115), and Nafion 212 (N-212) with respective thicknesses of 183, 127, and 50.08 μ, was separately incorporated into carbon cloth as PEM air-cathode electrode to evaluate their influences on the performance of the 2MA-CsS-AMFC configuration operated in fed-batch mode, while Azorubine dye was selected as the recalcitrant organic compound. The fed-batch test results showed that the 2MA-CsS-AMFC configuration with PEM N-115 operated at Azorubine dye concentration of 300 mg L−1 produced the highest power density of 1022.5 mW m−2 and open-circuit voltage (OCV) of 1.20 V coupled with enhanced dye removal (4.77 mg L h−1) compared to 2MA-CsS-AMFCs with PEMs N-117 and N-212 and those in previously published data. Interestingly, PEM 115 showed remarkable reduction in biofouling and pH splitting. Apart from that, mass transfer coefficient of PEM N-117 was the most permeable to oxygen (KO = 1.72 × 10−4 cm s−1) and PEM N-212 was the most permeable membrane to Azorubine (KA = 7.52 × 10−8 cm s−1), while PEM N-115 was the least permeable to both oxygen (KO = 1.54 × 10−4) and Azorubine (KA = 7.70 × 10−10). The results demonstrated that the 2MA-CsS-AMFC could be promising configuration for bioenergy recovery from wastewater treatment under various PEMs, while application of PEM N-115 produced the best performance compared to PEMs N-212 and N-117 and those in previous studies of membrane/membrane-less air-cathode single-chamber MFCs that consumed dye wastewater

Simultaneous acid red 27 decolourisation and bioelectricity generation in a (H-type) microbial fuel cell configuration using NAR-2

Microbial fuel cells (MFCs) represent one of the most attractive and eco-friendly technologies that convert chemical bond energy derived from organic matter into electrical power by microbial catabolic activity. This paper presents the use of a H-type MFC involving a novel NAR-2 bacterial consortium consisting of Citrobacter sp. A1, Enterobacter sp. L17 and Enterococcus sp. C1 to produce electricity whilst simultaneously decolourising acid red 27 (AR27) as a model dye, which is also known as amaranth. In this setup, the dye AR27 is mixed with modified P5 medium (2.5 g/L glucose and 5.0 g/L nutrient broth) in the anode compartment, whilst phosphate buffer solution (PBS) pH 7 serves as a catholyte in the cathode compartment. After several electrochemical analyses, the open circuit voltage (OCV) for 0.3 g/L AR27 with 24-h retention time at 30 °C was recorded as 0.950 V, whereas (93 %) decolourisation was achieved in 220-min operation. The maximum power density was reached after 48 h of operation with an external load of 300 Ω. Scanning electron microscopy (SEM) analysis revealed the surface morphology of the anode and the bacterial adhesion onto the electrode surface. The results of this study indicate that the decolourisation of AR27 dye and electrical power generation was successfully achieved in a MFC operated by a bacterial consortium. The consortium of bacteria was able to utilise AR27 in a short retention time as an electron acceptor and to shuttle the electrons to the anode surface for bioelectricity generation