[Show abstract][Hide abstract] ABSTRACT: The stress of poised cathode potential condition and carbon source switchover for functional biocathode microbial community influences is poorly understood. Using highthroughput functional gene array (GeoChip v4.2) and Illumina 16S rRNA gene MiSeq sequencing, we investigated the phylogenetic and functional microbial community of the initial inoculum and biocathode for bioelectrochemical reduction of nitrobenzene to less toxic aniline in response to carbon source switchover (from organic glucose to inorganic bicarbonate). Selective transformation of nitrobenzene to aniline maintained in the bicarbonate fed biocathode although nitrobenzene reduction rate and aniline formation rate were significantly decreased compared to those of the glucose-fed biocathode. When the electrical circuit of the glucose-fed biocathode was disconnected, both rates of nitrobenzene reduction and of aniline formation were markedly decreased, confirming the essential role of an applied electric field for the enhancement of nitrobenzene reduction. The stress of poised cathode potential condition led to clear succession of microbial communities from the initial inoculum to biocathode and the carbon source switchover obviously changed the microbial community structure of biocathode. Most of the dominant genera were capable of reducing nitroaromatics to the corresponding aromatic amines regardless of the performance mode. Heterotrophic Enterococcus was dominant in the glucose-fed biocathode while autotrophic Paracoccus and Variovorax were dominant in the bicarbonate-fed biocathode. Relatively higher intensity of diverse multi-heme cytochrome c (putatively involved in electrons transfer) and carbon fixation genes was observed in thebiocarbonate-fed biocathode, likely met the requirement of the energy conservation and maintained the nitrobenzene selective reduction capability after carbon source switchover. Extracellular pilin, which are important for biofilm formation and potential conductivity, had a higher gene abundance in the glucose-fed biocathode might explain the enhancement of electro-catalysis activity for nitrobenzene reduction with glucose supply. Dominant nitroaromatics-reducing or electrochemically active bacteria and diverse functional genes related to electrons transfer and nitroaromatics reduction were associated with nitrobenzene reduction efficiency of biocathode communities in response to carbon source switchover.
Water Research 05/2014; 54:137–148. · 4.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, BES with bioanode and biocathode was applied to decolorize an azo dye Congo red (CR). Results showed that the Congo red decolorization efficiency (CR-DE) within 23h in a combined bioanode-biocathode single chamber BES was 98.3±1.3%, significantly higher than that of mixed solution in a dual chamber BES (67.2±3.5%) (P<0.005). Various electrodes deployments (horizontal, vertical and surrounding) in the combined bioanode-biocathode BES were further compared based on the decolorization performance and electrochemical characterization. Results indicated that CR-DE within 11h improved from 87.4±1.3% to 97.5±2.3%, meanwhile the internal resistance decreased from 236.6 to 42.2Ω as modifying the horizontal deployment to be a surrounding deployment. It proved that the combination of bioanode and biocathode with suitable electrodes deployment could accelerate the decolorization of azo dye Congo red, which would be great potential for the application of bioelectrochemical technology in azo dye wastewater treatment.
[Show abstract][Hide abstract] ABSTRACT: Bioelectrochemical system (BES) that removes recalcitrant pollutant out of wastewater is of special interest for practice. This study modified the configuration of BES to be a sleeve-type with compact structure. Azo dye (acid orange 7, AO7) in the outer cathode chamber performed a complete decolorization by electrons supplied from acetate oxidized with electricigens in the inner anode chamber. The AO7 decolorization efficiency (DEAO7) was enhanced to be higher than 98% from 0.14 to 2.00mM. Electrochemical impedance spectroscopy (EIS) analysis showed that the internal resistance of anode, cathode and the whole cell was 26.4, 38.3, and 64.6Ω, respectively, indicating that the modified configuration with large area and small distance between anode and cathode can result in a lower internal resistance and higher decolorization performance. This is the first study for azo dye decolorization using sleeve-type configuration with highly efficient decolorization by abiotic cathode BES.
[Show abstract][Hide abstract] ABSTRACT: With the aim of enhanced degradation of azo dye alizarin yellow R (AY) and further removal of the low-strength recalcitrant matter (LsRM) of the secondary effluent as much as possible, our research focused on the combination of aerobic bio-contact oxidation (ABO) with iron/carbon microelectrolysis (ICME) process.
The combined ABO (with effective volume of 2.4 l) and ICME (with effectively volume of 0.4 l) process were studied with relatively short hydraulic retention time (HRT) of 4 or 6 h.
At the HRT of 6 h with the reflux ratio of 1 and 2, the AY degradation efficiency in the final effluent was >96.5%, and the total organic carbon (TOC) removal efficiency were 69.86% and 79.44%, respectively. At the HRT of 4 h and the reflux ratio of 2, TOC removal efficiency and AY degradation efficiency were 73.94% and 94.89%, respectively. The ICME process obviously enhanced the total AY removal and the generated micromolecule acids and aldehydes then that wastewater backflow to the ABO where they were further biodegraded.
The present research might provide the potential options for the advanced treatment azo dyes wastewater with short HRT and acceptable running costs.
Environmental Science and Pollution Research 06/2012; 19(5):1385-91. · 2.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A sediment microbial fuel cell (SMFC) with three dimensional floating biocathode (FBC) was developed for the electricity generation
and biodegradation of sediment organic matter in order to avoid negative effect of dissolved oxygen (DO) depletion in aqueous
environments on cathode performance and search cost-effective cathode materials. The biocathode was made from graphite granules
with microbial attachment to replace platinum (Pt)-coated carbon paper cathode in a laboratory-scale SMFC (3 L in volume)
filled with river sediment (organic content 49±4 g·kg−1 dry weight). After start-up of 10 days, the maximum power density of 1.00W·m−3 (based on anode volume) was achieved. The biocathode was better than carbon paper cathode catalyzed by Pt. The attached biofilm
on cathode enhanced power generation significantly. The FBC enhanced SMFC performance further in the presence aeration. The
SMFC was continuously operated for an over 120-day period. Power generation peaked within 24 days, declined gradually and
stabilized at a level of 1/6 peak power output. At the end, the sediment organic matter content near the anode was removed
by 29% and the total electricity generated was equal to 0.251 g of chemical oxygen demand (COD) removed.
Frontiers of Environmental Science & Engineering in China - FRONT ENVIRON SCI ENG CHINA. 01/2012;
[Show abstract][Hide abstract] ABSTRACT: With limited external applied voltage, the microbial electrolysis cell (MEC) could produce hydrogen by exoelectrogenic microorganisms. The present study revealed that a cubiod-shaped chamber effectively reduces the distance between electrodes and thereby reduces the internal resistance of the entire cell. With 0.6 V of applied voltage, the cuboid MEC had a columbic efficiency of 33.7%, much higher than that achieved in the H-shaped MEC test (ca. 15%) of comparable size. Filling the anode chamber with granular activated carbon further enhanced the columbic efficiency to 45%. The corresponding hydrogen conversion rate could reach 35%.
International Journal of Hydrogen Energy 01/2010; · 3.55 Impact Factor