Search

[Display omitted] • Aerotolerant bioanode was constructed with small external resistance or high shear stress. • Aerotolerant biofilm was flat and compact with a large laminar boundary layer for reducing oxygen diffusion. • Compact electrode assembly MFC with aerotolerant bioanode achieved a power density of 4300 mW/m2. Reducing electrode spacing is considered the most effective way to maximize the power density of microbial fuel cell (MFC) due to the effective reduction of internal resistance. However, reducing electrode spacing presents the challenge of diffusing oxygen from the cathode to the anode, thereby reducing anode performance. Constructing aerotolerant anode may be one of the effective ways to minimize the effect of oxygen on anode performance. Here, we report that using small external resistance or maintaining high nitrogen sparging rate during bioanode enrichment could significantly enhance the aerotolerant characteristic of the bioanode. The voltage loss affected by oxygen was significantly reduced and, as a result, the power density of the compact electrode assembly MFC increased by 85% reaching 4300 mW/m2. The aerotolerant bioanode had a flat and compact biofilm structure and a larger laminar boundary layer (over 300 μm) to reduce oxygen diffusion, while the aerointolerant bioanode had a rough and porous biofilm structure and a smaller laminar boundary layer (less than 80 μm). The microbial community of all the bioanodes was dominated by Geobacter (over 55%). Therefore, this study provides a sample way to construct an aerotolerant bioanode for high power generation in MFCs. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) have the potential for simultaneous electricity generation and nitrogen removal in the treatment of wastewater that contains nitrate, but the denitrification of nitrate might affect electricity generation in single-chamber MFCs. In this study, the effect of nitrate on electricity generation in single-chamber air cathode MFCs was investigated. The chemical oxygen demand (COD) was removed faster by denitrification (0.977 ± 0.013 g COD g −1 NO 3 − ) than by electricity generation in the MFCs. When the concentration of COD that excluded the COD removed by denitrification was more than 300 mg O 2  L −1 , denitrification only resulted in the decrease in the voltage of the MFCs at the denitrification stage, but did not affect the stable voltage and maximum power density (MPD) of the MFCs after the denitrification stage. The average MPDs during the 660-day batch operation ranged from 27.4 ± 0.9 to 28.4 ± 1.2 W m −3 . At the same concentration of COD that excluded the COD removed by denitrification, the coulombic efficiency of the MFCs after the denitrification process increased with an increasing initial concentration of nitrate, which was probably attributed to the inhibition of the activity of certain non-exoelectrogenic bacteria by nitrate. A microbial community analysis showed that Thauera was the dominant genus of denitrifying bacteria and Geobacter was the dominant genus of exoelectrogenic bacteria at the anodes of the MFCs. With an increase in the initial concentration of nitrate, the proportion of denitrifying bacteria increased, whereas the proportion of exoelectrogenic bacteria decreased. [ABSTRACT FROM AUTHOR]

• Low cost electrochemical filtration carbon membrane (ECM) was developed from coal via self-bonding. • ECM exhibits good comprehensive performance. • PVB is a good pore former to improve the pore structure of ECM. • ECM exhibits high removal rate for four typical organic pollutants at applied voltage of 2.0 V. • Oxidation mechanism of ECM includes both direct oxidation and indirect oxidation. Electrochemical filtration membranes are highly effective for wastewater treatment. However, their relatively high production cost may limit their large-scale production and industrial application. In this work, a low-cost and efficient electrochemical filtration carbon membrane (ECM) was developed via a simple method using coal as the precursor and relying on its self-bonding property. The effects of raw coal blending ratio, carbonization temperature and the addition of pore former on the performance of ECMs were systematically studied. The electrochemical filtration efficiency of the ECM was evaluated using four typical organic pollutants (phenol, bisphenol A (BPA), tetracycline (TC) and rhodamine B (RhB)). Finally, the oxidation mechanism of the ECM was also explored. The high caking property of the raw coal resulted in high mechanical strength ECMs but also led to low porosity and small pore size, which may cause high hydraulic resistance. The overall performance of the ECMs was improved by using blended coal samples as raw materials. The ECM obtained by the optimal preparation conditions exhibited a porosity value of 51.83%, mean pore width of 0.88 μm, mechanical strength of 78.8 N, electrical resistivity of 33.91 mΩ cm and high permeability (393.17 L·m−2·h−1·bar−1). Under a cell potential of 2.0 V, the removal rates of the ECM for all four pollutants were greatly enhanced by electrochemical oxidation, and the electrochemical oxidation activity of the ECM involve both direct and indirect oxidation. Overall, these results demonstrated the potential applicability of ECMs for large-scale production and organic wastewater treatment. [ABSTRACT FROM AUTHOR]

• The 3D crateriform and honeycomb polymer capsule was fabricated via one step titration-gel method. • The interior channel surface of the SPSC with nano fiber screen mesh and re-entrant structures. • The prepared SPSC has high adsorbed capacity against cationic dyes even in multi-component systems. • The prepared SPSC can be used in wide range pH situations and regenerated at least 3 times. • The SPSC has good prospects for excessive removing weak polarity cationic dyes from alkaline wastewater. In this study, a hybrid sodium alginate-polyvinyl alcohol-silica oxide capsule (SA-PVA-SiO 2 capsule, SPSC) was fabricated via the one-step titration-gel method that directly dripped the spherical droplet of the SA, PVA and tetraethyl orthosilicate (TEOS) mixed solutions into the bath with calcium chloride (CaCl 2), NaCl and oversaturated boric acid (H 3 BO 3) cross-linking agents. The formation principle of the prepared capsule was investigated. And the adsorptive performance of the SPSC was analyzed by removing the single, binary and multi-component cationic dye solutions [i.e. Methylene Blue (MB), Malachite Green (MG) and Crystal Violet (CV)]. The results indicated that the crateriform and cellular polymer channel with nano screen mesh and re-entrant structures could help to promote the interaction between pollutants and the interface of the SPSC thereby trapping the cationic dyes in its body. In single-component dye solution, the maximal adsorption capacities of the SPSC against MB, MG and CV were respectively found to be 394.077 mg/g, 1034.047 mg/g and 1756.202 mg/g at 25 °C and pH 9. The adsorption mechanism of the cationic dyes by the SPSC was governed by electrostatic attraction and chemisorption. Though the removal capacity of the cationic dyes by the SPSC was reduced in competitive multi-component systems, the saturation adsorption amount of the CV could still maintain above 684,692 mg/g. The affinity between the SPSC and the cationic dyes was in the order of MB > MG > CV. The prepared hydrogel capsule could be used in wide range pH situations. This facile method which was used to produce free-standing spherical support adsorbent with specialized morphology might have good prospects for excessive removing cationic dyes from alkaline wastewater. [ABSTRACT FROM AUTHOR]