Treatment of isopropanol wastewater in an anaerobic fluidized bed microbial fuel cell filled with macroporous adsorptive resin as multifunctional biocarrier

Diffusion-Controlled Crystal Engineering with Diverse Antisolvent Intervention for the Preparation of High-Quality Hybrid Perovskite Films

Antisolvent engineering is routinely used to modulate the crystallization of perovskite films as they can offer an additional driving force for nucleation. Actually, the intervention of antisolvent into nucleation is thought to involve some relatively fast and complex processes, which, however, are not fully understood so far. Here, the diffusion of the organic amine cation FA+ (one dominated precursor) and its distribution in a spin-coating process in different antisolvents is simulated by the computational fluid dynamics (CFD) model. It is suggested that a moderate diffusion rate (like that in the case of toluene as an antisolvent) not only enables to form a very uniform distribution of FA+ ions on the substrate, beneficial to the uniform nucleation of the intermediate phase, but also can balance the nucleation and growth rates of the intermediate phase, thereby suppressing undesired heterogeneous nucleation and growth. Results show that the perovskite film fabricated using toluene as an antisolvent has a high quality, based on which higher power conversion efficiencies of up to 24.32% are achieved for perovskite solar cells.

Treatment of phenolic wastewater by anaerobic fluidized bed microbial fuel cell using carbon brush as anode: microbial community analysis and m-cresol degradation mechanism

Anaerobic fluidized bed microbial fuel cell (AFB-MFC) is a technology that combines fluidized bed reactor and microbial fuel cell to treat organic wastewater and generate electricity. The performance and the mechanism of treating m-cresol wastewater in AFB-MFC using carbon brush as biofilm anode were studied. After 48 h of operation, the m-cresol removal efficiency of AFB-MFC, MAR-AFB (fluidized bed bioreactor with acclimated anaerobic sludge), MAR-FB (ordinary fluidized bed reactor with only macroporous adsorptive resin) and AST (traditional anaerobic sludge treatment) were 95.29 ± 0.67%, 85.78 ± 1.81%, 71.24 ± 1.86% and 70.41 ± 0.32% respectively. The maximum output voltage and the maximum power density of AFB-MFC using carbon brush as biofilm anode were 679.7 mV and 166.6 mW/m2 respectively. The results of high-throughput sequencing analysis indicated the relative abundance of dominant electroactive bacteria, such as Trichococcus, Geobacter, and Pseudomonas, on the anode carbon brushes was higher than that of AST, and also identified such superior m-cresol-degrading bacteria as Bdellovibrio, Thermomonas, Hydrogenophaga, etc. Based on the determination of m-cresol metabolites detected by Gas Chromatography-Mass Spectrometry (GC-MS), the possible biodegradation pathway of m-cresol under anaerobic and aerobic conditions in AFB-MFC was speculated. The results showed that m-cresol was decomposed into formic acid-acetic anhydride and 3-methylpropionic acid under the action of electrochemistry, which is a simple degradation pathway without peripheral metabolism in AFB-MFC.

Ionic resource recovery for carbon neutral papermaking wastewater reclamation by a chemical self-sufficiency zero liquid discharge system

Papermaking industry discharges large quantities of wastewater and waste gas, whose treatment is limited by extra chemicals requirements, insufficient resource recovery and high energy consumption. Herein, a chemical self-sufficiency zero liquid discharge (ZLD) system, which integrates nanofiltration, bipolar membrane electrodialysis and membrane contactor (NF-BMED-MC), is designed for the resource recovery from wastewater and waste gas. The key features of this system include: 1) recovery of NaCl from pretreated papermaking wastewater by NF, 2) HCl/NaOH generation and fresh water recovery by BMED, and 3) CO₂ capture and NaOH/Na₂CO₃ generation by MC. This integrated system shows great synergy. By precipitating hardness ions in papermaking wastewater and NF concentrate with NaOH/Na₂CO₃, the inorganic scaling on NF membrane is mitigated. Moreover, the NF-BMED-MC system with high stability can simultaneously achieve efficient CO₂ removal and sustainable recovery of fresh water and high-purity resources (NaCl, Na₂SO₄, NaOH and HCl) from wastewater and waste gas without introducing any extra chemicals. The environmental evaluation indicates the carbon-neutral papermaking wastewater reclamation can be achieved through the application of NF-BMED-MC system. This study establishes the promising of NF-BMED-MC as a sustainable alternative to current membrane methods for ZLD of papermaking industry discharges treatment.

Recent progress in microbial fuel cells using substrates from diverse sources

Increasing untreated environmental outputs from industry and the rising human population have increased the burden of wastewater and other waste streams on the environment. The most prevalent wastewater treatment methods include the activated sludge process, which requires aeration and is, therefore, energy and cost-intensive. The current trend towards a circular economy facilitates the recovery of waste materials as a resource. Along with the amount, the complexity of wastewater is increasing day by day. Therefore, wastewater treatment processes must be transformed into cost-effective and sustainable methods. Microbial fuel cells (MFCs) use electroactive microbes to extract chemical energy from waste organic molecules to generate electricity via waste treatment. This review focuses use of MFCs as an energy converter using wastewater from various sources. The different substrate sources that are evaluated include industrial, agricultural, domestic, and pharmaceutical types. The article also highlights the effect of operational parameters such as organic load, pH, current, and concentration on the MFC output. The article also covers MFC functioning with respect to the substrate, and the associated performance parameters, such as power generation and wastewater treatment matrices, are given. The review also illustrates the success stories of various MFC configurations. We emphasize the significant measures required to fill in the gaps related to the effect of substrate type on different MFC configurations, identification of microbes for use as biocatalysts, and development of biocathodes for the further improvement of the system. Finally, we shortlisted the best performing substrates based on the maximum current and power, Coulombic efficiency, and chemical oxygen demand removal upon the treatment of substrates in MFCs. This information will guide industries that wish to use MFC technology to treat generated effluent from various processes.

Distribution modes of residual carbon and ash in coal gasification fine slag and its feasibility analysis as particle electrodes

From the perspective of environmental protection and resource utilization, the feasibility of treating m-cresol wastewater with coal gasification fine slag (GFS) as particle electrodes in an electrocatalytic system was evaluated to achieve the purpose of treating waste with waste. Characterization by scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), Raman, and fourier transform infrared spectroscopy (FTIR) confirmed that the GFS featured a diverse inorganic framework, large specific surface area (as large as above 155 m² g^-1), hierarchical porous structure, and plenty of catalytic sites. The Venn diagram method was used to systematically propose the following distribution modes of residual carbon (RC) and ash in GFS: discrete distribution, embedded distribution, crosslinked distribution, and association and bonding. Only 8 g L^-1 of GFS particle electrodes prevented the formation of a yellow sticky passivation film on the anode. Compared to the two-dimensional electrocatalytic system (47.89%), the wastewater treatment efficiency was increased by 108.81%. Zero-order kinetic results showed that the reaction rate constant was the highest (2.1106 mg L^-1·min^-1) when the secondary flotation RC was adopted as particle electrodes. It was indicated that GFS in discrete mode played either no role or at most a minor role. Last but not least, the synergy of RC and ash was revealed from a molecular perspective. The RC exhibited hierarchical microporous/mesoporous/macroporous structure, which facilitated the entry of H₂O₂ into the catalytic sites of ash. Abundant catalytic sites in ash accelerated adsorption and oxidation processes on RC surfaces.

Study on the mechanism of anaerobic fluidized bed microbial fuel cell for coal chemical wastewater treatment

The coal chemical wastewater (CCW) was treated by anaerobic fluidized bed microbial fuel cell (AFB-MFC) with macroporous adsorptive resin (MAR) as fluidized particle. Isosteric heat calculation and molecular dynamics simulation (MDS) have been performed to study the interaction between organics of CCW and MAR. The isosteric heat of MAR to m-cresol was the largest at 65.4961 kJ/mol, followed by phenol. Similarly, the diffusion coefficient of m-cresol on MAR was the largest, which was 0.04350 Ų/ps, and the results were verified by the kinetic adsorption experiments. Microbial community analysis showed that the dominant bacteria in activated sludge of MFC fed with CCW were acinetobacter, aeromonas, pseudomonas and sulfurospirillum. The synergistic cooperation of bacteria contributed to improving CCW degradation and the power generation of MFC. Headspace-gas chromatography-mass spectrometry (HS-GC-MS) was used to detect intermediate of organics in CCW. It was proved that the intermediate of m-cresol degradation was 4-methyl-2-pentanone and acetic acid, and the intermediate of phenol degradation included cyclohexanone, hydroxyhexanedither and hydroxyacetic acid. Combined with the highest occupied molecular orbital (HOMO) analysis results of organic matter obtained by molecular simulation, the degradation pathway of organic matter in CCW was predicted. The energy of organics degradation pathway was analyzed by Materials Studio (MS) software, and the control step of organics degradation was determined.

Enhancement of isopropanol removal with concomitant power generation by microbial fuel cells: Optimization of deoxidizing composite anodes using response surface methodology

This study used a response surface method to develop a deoxidizing anode, which was introduced into microbial fuel cells (MFCs) to treat isopropanol (IPA) wastewater and waste gas. By embedding a deoxidizing agent (DA) into the anode of MFCs, a hypoxic environment can be created to enable anaerobic electrogens to be effectively attached to the anode surface and grow. Consequently, MFC power generation performance can be enhanced. The optimal coke and conductive carbon black ratio of an anode and percentage of DA added were 3.61 g/g and 3.15 %, respectively. The research design concurrently achieved the maximum deoxygenation efficiency (0.86 mg O₂/bead), minimum disintegration ratio (3.51 %), and minimum resistance (30.2 Ω). The regression model had high prediction power (R² > 0.93) for anode performance. As determined through multi-objective optimization, the results highly satisfied the target expectation (desirability = 0.82). The optimized deoxidizing anode was filled into an air-cathode MFC, which had a higher IPA removal efficiency (1.15-fold) and voltage output (1.24-fold) than an MFC filled with coke. The results for the trickling-bed MFC filled with a deoxidizing anode revealed that when the inlet concentration was 0.74 g/m³, the voltage output and power density were highest at 416.3 mV and 486.6 mW/m³, respectively. The deoxidizing anode developed has the potential to increase the MFC voltage output and the pollutant removal.

Real-time monitoring of the column chromatographic process of Phellodendri Chinensis Cortex part II: multivariate statistical process control based on near-infrared spectroscopy

Multivariate statistical process control has been successfully used for the real-time monitoring of the column chromatographic process of Phellodendri Chinensis Cortex.

Study on Start-Up Membraneless Anaerobic Baffled Reactor Coupled with Microbial Fuel Cell for Dye Wastewater Treatment

In this study, the antitoxicity performance of the traditional anaerobic baffled reactor (ABR) and the newly constructed membraneless anaerobic baffled reactor coupled with microbial fuel cell (ABR-MFC) was compared for the treatment of simulated printing and dyeing wastewater under the same hydraulic residence time. The sludge performances of ABR-MFC and ABR were evaluated on the dye removal rate, extracellular polymer (EPS) content, sludge particle size, methane yield, and the surface morphology of granular sludge. It was found that the maximum power density of the ABR-MFC reactor reached 1226.43 mW/m³, indicating that the coupled system has a good power generation capacity. The concentration of the EPS in the ABR-MFC reactor was about 3 times that in the ABR, which could be the result of the larger average particle size of sludge in the ABR-MFC reactor than in the ABR. The dye removal rate of the ABR-MFC reactor (91.71%) was higher than that of the ABR (1.49%). The methane production and microbial species in the ABR-MFC system were higher than those in the ABR. Overall, the MFC embedded in the ABR can effectively increase the resistance of the reactor, promote the formation of granular sludge, and improve the performance of the reactor for wastewater treatment.