Oily sludge is a major problem affecting the quality of oil fields and surrounding environment. Microbial fuel cell (MFC) technology is a simple way to treat the oily sludge while generating electricity. To investigate the electrochemical properties of such MFC and the characteristics of bacteria attached to anode, a single‐chamber MFC supplemented with oily sludge was constructed. The electrochemical results showed that the oily sludge is suitable for MFC operation, with a maximum output voltage of 299.13 mV and a maximum output power (Pmax) of 2,255.52 mW/m2. The cyclic voltammetry curve of MFC anode displayed an “S” shape, whereas the main peaks were at 0 and 0.1 V, indicating a strong redox reaction on the anode carbon felt. The limiting current was 0.08 A/cm2. The scanning electron microscopy (SEM) of the bacteria on the anode surface showed that most of bacteria displayed a rod‐shaped morphology, whereas the biological metagenomic classification sequencing showed that the predominant electricity‐producing bacteria were Proteiniciclasticum (15.83%) from Firmicutes and Pseudomonas (11.9%) from Gammaproteobacteria. MFC can effectively utilize the oily sludge to generate electricity at the same time, which provides a theoretical basis for the research of MFCs' pollution control and electricity production.
Microbial fuel cell (MFC) technology is a simple way to accelerate the treatment of the oily sludge which is a major problem affecting the quality of oil fields and surrounding environment while generating electricity. To investigate the oil removal and the characteristics of changes in the composition of bacteria, sediment microbial fuel cells (SMFCs) supplemented with oily sludge was constructed. The results showed that the degradation efficiency of total petroleum hydrocarbon (TPH) of SMFC treatment was 10.1 times higher than the common anaerobic degradation. In addition, the degradation rate of n-alkanes followed the order of high carbon number > low carbon number > medium carbon number. The odd–even alkane predominance (OEP) increased, indicating that a high contribution of even alkanes whose degradation predominates. The OUT number, Shannon index, AEC index, and Chao1 index of the sludge treated with SMFC (YN2) are greater than those of the original sludge (YN1), showing that the microbial diversity of sludge increased after SMFC treatment. After SMFC treatment the relative abundance of Chloroflexi, Bacteroidia and Pseudomonadales which are essential for the degradation of the organic matter and electricity production increased significantly in YN2. These results will play a crucial role in improving the performance of oily sludge MFC.
The anode is considered to be a key factor to improve
the single-chamber
bioelectrochemical system’s efficiency to degrade oily sludge
in sediment while generating electricity. There are few studies on
the effect of the anode structure on the performance of oily sludge
MFCs systematically. In this paper, an oily sludge bioelectrical system
was constructed using carbon felt and carbon plate as anode materials,
adjusting the anode material arrangement as transverse and longitudinal,
and using different anode materials from single to sextuple anodes.
The results of this study showed that the rate of degradation of oily
sludge was greater with carbon felt (17.04%) than with the carbon
plate (13.11%), with transverse (23.61%) than with the longitudinal
(19.82%) arrangement of anodes, and with sextuple anodes (33.72%)
than with a single anode (25.26%) in the sediment microbial fuel cells
(SMFCs). A similar trend was observed when the voltage, power density,
and electromotive force (EMF) of SMFCs were estimated between the
carbon felt and carbon plate, transverse and longitudinal arrangements,
single and sextuple anodes. It is concluded that the proper adjustment
of anode arrangements, using carbon felt as an anode material, and
increasing the number of anodes to six may accelerate the rate of
degradation of oily sludge in oily sludge sediment microbial fuel
cells (SMFCs). Furthermore, the electricity generation performance
was also improved.
Electricity-generating bacteria as biocatalysts for microbial fuel cells (MFCs), and their species and power generation performance determine the performance of the MFC for pollution control and power generation. For that purpose, an electricity-generating bacteria isolated from the oily sludge MFCs, and adjusted the adaptability of nitrogen-to-phosphorus ratio (3.67:1, 4.67:1, 5.67:1, and 6.67:1), temperature (5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃) and pH (pH = 6, 6.5, 7, 7.5, 8). The results of this study showed that electricity-generating bacteria was identified as Bacillus cereus, with a rod-shaped cell, about 0.5-1.0 µm in length. The optimal nitrogen-phosphorus ratio, temperature and pH of MFCs were 4.67:1, 25 ℃ and pH = 7, respectively, and its output voltage was up to 168.05 mV. The study of this functional bacteria will provide beneficial assistance for the improvement of oil removal and power generation performance of oily sludge MFCs.
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