Treatment of cassava mill wastewater and production of electricity through microbial fuel cell technology

Cassava mill wastewater has a high organic content and is an important economic product of traditional and rural low technology agro-industry in many parts of the world. This study explores the utilization of agro-industrial wastewater collected from cassava mills as a resource for electricity generation by microbial fuel cells (MFCs). Mixed culture sludge was used to inoculate the bottom chamber of the MFCs whilst cassava mill wastewater was used in the MFCs. Experimental results showed that the MFCs could generate electricity from full-strength cyanide laden wastewater (16000 mg-COD/L, 86 mg/L cyanide) with a maximum power density of 1771 mW/m². The results from this study demonstrate the feasibility of using MFC technology to generate electricity whilst simultaneously treating cyanide laden cassava mill wastewater effectively. Using MFCs for cassava mill wastewater treatment provides an attractive way to reduce the cost of wastewater treatment in addition to generating electricity.     

TiO2 NTAs decorated with thin CuBi2O4 nanosheets for efficient photocatalytic dye degradation and hydrogen generation

Photocatalytic technology is the recent investigation focus because of the wide applications in sewage disposal and new energy generation. In this paper, the optical and photocatalytic properties of TiO₂ NTAs were enhanced by the hydrothermal deposition of CuBi₂O₄ by regulating the precursor concentration. The results indicated that the precursor concentration played remarkable influences on the morphology and photocatalytic ability. The mild reagent concentration was in favor of super-thin CuBi₂O₄ nanosheet formation. CuBi₂O₄/TiO₂ NTAs with high reagent concentration exhibited high photocurrent and hydrogen production, and showed outstanding performance in the removal of organic dyes and heavy metal ions. The free radical production and the photocatalytic progress were introduced in detail. The high photocatalytic activity exhibits prospective foreground in industrial waste water treatment and novel energy resource development.     

TiO_2光催化氧化处理废水的研究概况

TiO2光催化氧化法降解废水是目前废水处理方面的热点,为彻底解决废水处理问题提供了新的手段。综述了TiO2光催化氧化降解废水的反应机理、影响因素及提高光催化效率的途径。同时,指出了光催化降解废水技术需要进一步解决的问题。     

Electricity generation from molasses wastewater by an anaerobic baffled stacking microbial fuel cell

BACKGROUND: The conventional treatment of molasses wastewater has many disadvantages including intensive energy requirements, excessive chemicals consumption and large quantities of waste generation. The microbial fuel cell (MFC) is a promising technology for power generation along with wastewater treatment. However, low power output and high construction costs limit the scale‐up and field implementation of MFCs. In this study, a novel anaerobic baffled stacking microbial fuel cell (ABSMFC) composed of four units was constructed and used to treat molasses wastewater. RESULTS: The ABSMFC was operated at three different organic loading rates (OLRs) and the highest average power density of 115.5 ± 2.7 mW m^?2 was achieved for the four units at an OLR of 3.20 kg COD m^?3 d^?1. Accordingly, 50–70% of total COD removal efficiency was accomplished. Power generation was further improved in terms of voltage or current by connecting units in series or parallel. The low voltage loss (8.1%) during series connection resulted from low parasitic current of adjacent units. CONCLUSION: The ABSMFC is effective for molasses wastewater treatment. It can promote current or voltage output and minimize energy loss during series connection. This is a promising scalable architecture and can be combined with other existing wastewater treatment technologies. Copyright © 2010 Society of Chemical Industry     

微生物燃料电池处理丙酮和氨氮废水及同步产电性能研究

本研究利用阴离子交换膜作为分隔膜构建了生物阴极微生物燃料电池（Microbial fuel cell, MFC），通过硝化反硝化过程去除氨氮、降解丙酮同时产电。实验探究了不同丙酮浓度（50 mg/L、100 mg/L、300 mg/L、500 mg/L、700 mg/L）对MFC产电及氨氮（200 mg/L）的去除效果。结果表明，在选定的丙酮浓度范围内，丙酮的去除率均高达96%以上；当丙酮浓度高于300 mg/L时，氨氮的去除开始受到抑制，氨氮最高去除率为73.7%，且丙酮浓度为300 mg/L时，对应的MFC的产电性能最佳，最高输出功率密度可达49.7 mW/m2。高通量测序技术分析了阳极及阴极微生物群落结构，从门级分类上看，阳极中的优势微生物群落主要为变形菌，拟杆菌门及厚壁菌门；阴极上的优势微生物群落为拟杆菌门、放线菌门、变形菌门及酸杆菌门。从属级分类上看，阳极主要的优势菌种为Comamonas, Acetoanaerobium，Stenotrophomonas。阴极主要的优势菌种为Rhodococcus，Aridibacter, Thauera，Ignavibacterium。     

Controlled synthesis of TiO2 nanorod arrays immobilized on ceramic membranes with enhanced photocatalytic performance

In this work, TiO₂ nanorod arrays (NRAs) were synthesized directly on flat sheet Al₂O₃ ceramic membrane (CM) substrates by a two-step hydrothermal method. The effects of the addition of anions and cations and the preparation parameters in the second step on the morphology and size of TiO₂ were investigated in detail, and the photocatalytic activities of the as-synthesized TiO₂-loaded ceramic membranes were investigated by the degradation of methylene blue (MB) under UV light. The results highlighted that the growth of TiO₂ on the CM strongly depended on the synthesis conditions. The anions of Cl^- and Br^- were favorable for the further growth of TiO₂ nanorods, while the anions of SO₄^2- and PO₄^3- with larger ionic radius and higher charge number could retard the growth of TiO₂ nanorods. The SO₄^2- and PO₄^3- could accelerate the formation of nanospheres or nanosheets, respectively. The cation like Na⁺, K⁺, Mg²⁺ and Ca²⁺ had no obvious impact on the formation of TiO₂ NRAs. TiO₂ nanorods exhibited the highest photocatalytic activity, as about 2.2 and 1.9 times larger than those of TiO₂ nanosheets and TiO₂ nanospheres, respectively. More importantly, the as-synthesized TiO₂ NRAs-loaded ceramic membrane could be easily reused and exhibited better photocatalytic stability. These findings would aid the development of TiO₂ photocatalytic materials with high performance.     

Development of microbial fuel cell with anoxic/oxic design for treatment of saline seafood wastewater and biological electricity generation

BACKGROUND: Sustainable technologies need to be developed to treat saline seafood wastewater (SSW) efficiently. This study focused on the feasibility of a continuously operated microbial fuel cell (MFC) with modified anoxic/oxic (A/O) architecture (A/O–MFC) for power generation and treatment of SSW simultaneously. RESULTS: Hydraulic retention time (HRT) was shown to have an impact on polarization and power output of the A/O–MFC and the maximum power density of 16.2 W m^?3 was obtained at a current density of 41.7 A m^?3 and HRT of 4.2 h. High salinity together with advective flow mode enabled a low and constant internal resistance of approximately 100 Ω throughout the experiments. Besides, pH of waste stream in both compartments was found always near neutral level. Increasing HRT could improve eliminability of soluble chemical oxygen demand (sCOD) and biological nitrification. CONCLUSIONS: This study provides a proof‐in‐concept demonstration to utilize an MFC for effective and sustainable treatment of SSW along with recovery of electrical energy. Copyright © 2010 Society of Chemical Industry     

利用无膜微生物燃料电池废水处理并回收电能

An upflow mode membrane-less microbial fuel cell （ML-MFC） was designed for wastewater treatment. Granular graphite electrodes, which are flexible in size, were adopted in the ML-MFC. Microbes present in anaerobic activated sludge were used as the biocatalyst and artificial wastewater was tested as substrate. During the electrochemically active microbe enrichment stage, a stable power output of 536 mW.m-3 with reference to the anode volume was generated by the ML-MFC running in batch mode. The voltage output decreased from 203 mV to about 190 mV after the ML-MFC was changed from batch mode to normally continuous mode, indicating that planktonic electrochemically active bacterial strains in the ML-MFC may be carried away along with the effluent. Cyclic voltammograms showed that the attached microbes possessed higher bioelectrochemical activity than the planktonic microbes. Forced aeration to the cathode benefited the electricity generation obviously. Higher feeding rate and longer electrode distance both increased the electricity generation. The coulombic yield was not more than 20% throughout the study, which is lower than that of MFCs with membrane. It is proposed that dissolved oxygen diffused from the cathode to the anode may consume part of the substrate.     

电极改性强化微生物燃料电池产电同步降解有机污染物研究进展

微生物燃料电池(MFC)是一种利用微生物作为催化剂就能实现同步产电及降解有机污染物的绿色能源装置.电极作为MFC的重要组成部分,在提高污染物降解及产电能力方面发挥着至关重要的作用.介绍了MFC电极,主要包括碳基/合成材料修饰电极、导电聚合物/复合物修饰电极、金属/金属氧化物修饰电极及其他材料修饰电极及其最新研究进展,对...     

A microbial fuel cell–electro‐oxidation system for coking wastewater treatment and bioelectricity generation

BACKGROUND: Coking wastewater is generated from coal coking, coal gas purification, and by‐product recovery processes. Increased interest is being focused on finding more sustainably effective and energy‐efficient methods for treating this wastewater. In this work, a system termed microbial fuel cell‐electro‐oxidation (MFC‐EO) was developed for simultaneous coking wastewater treatment and bioelectricity generation. RESULTS: Raw coking wastewater was first treated using MFCs. Power production, removal of total chemical oxygen demand (TCOD) and total nitrogen (TN) reached 538 ± 9 mW m^?2, 52 ± 1% and 50 ± 1%, respectively. Wastewater strength and phosphate addition were evaluated for the enhancement of power production and treatment efficiency. At the EO stage, the effect of current density and chloride concentration on pollutant abatement, current efficiency (CE_EO) and energy consumption (EC_EO) were investigated. The overall removal of TCOD and TN was 82 ± 1% and 68 ± 1%, respectively using the MFC‐EO process. CONCLUSIONS: A MFC‐EO process was developed for the first time for simultaneous bioelectricity generation and coking wastewater treatment. This study attempted to combine MFCs with a conventional EO process for coking wastewater treatment. Further strategies need to be investigated to optimize reactor configuration using low‐cost and highly efficient electrode materials. Copyright © 2009 Society of Chemical Industry     

微生物燃料电池与人工湿地耦合系统研究进展

将微生物燃料电池(microbial fuel cell, MFC)与人工湿地(constructed wetland, CW)相结合是近几年来出现的一种新型产能及废水净化工艺。在综述CW-MFC耦合系统产电机理及其发展的基础上进一步分析讨论了当前研究中影响系统性能的组成要素(植物、微生物、电极及分隔材料)和运行参数(碳源、氧化还原电位及水力停留时间)两个方面,最后总结了当前尚未解决的关键问题,对今后耦合系统的潜在应用进行了展望。     

微生物燃料电池处理偶氮含盐废水的产电性能和降解过程

偶氮含盐废水生化处理流程复杂、电耗高,且降解机理尚不明确。本研究基于酸性重铬酸钾法水热处理获取改性阳极,进而构建微生物燃料电池（microbial fuel cell,MFC）对偶氮含盐废水进行处理。考察了不同二价阴离子对MFC产电性能和降解有机物效果的影响,并探究了MFC对直接红13的降解机理。结果表明,偶氮含盐废水中含有硫酸钠时的产电性能高于含有碳酸钠的情况,MFC最大功率密度为265.38mW/m²、最大电流密度为1.10A/m²;MFC处理偶氮含盐废水时,对直接红13的去除率低于无额外添加盐时的效果（71.13%）,对葡萄糖共基质的降解影响程度为：添加硫酸钠>添加碳酸钠>无额外添加盐。微生物群落和降解产物分析表明,MFC阳极生物膜通过变形菌门、拟杆菌门等微生物的协同作用实现了对直接红13的生物电化学降解,产电下降解产物以还原产物芳香胺为主。     

Electrochemical characteriztion of the bioanode during simultaneous azo dye decolorization and bioelectricity generation in an air-cathode single chambered microbial fuel cell

To achieve high power output based on simultaneously azo dye decolorization using microbial fuel cell (MFC), the bioanode responses during decolorization of a representative azo dye, Congo red, were investigated in an air-cathode single chambered MFC using representative electrochemical techniques. It has been found that the maximum stable voltage output was delayed due to slowly developed anode potential during Congo red decolorization, indicating that the electrons recovered from co-substrate are preferentially transferred to Congo red rather than the bioanode of the MFC and Congo red decolorization is prior to electricity generation. Addition of Congo red had a negligible effect on the Ohmic resistance (R_ohm) of the bioanode, but the charge-transfer resistance (R_c) and the diffusion resistance (R_d) were significantly influenced. The R_c and R_d firstly decreased then increased with increase of Congo red concentration, probably due to the fact that the Congo red and its decolorization products can act as electron shuttle for conveniently electrons transfer from bacteria to the anode at low concentration, but result in accelerated consumption of electrons at high concentration. Cyclic voltammetry results suggested that Congo red was a more favorable electron acceptor than the bioanode of the MFC. Congo red decolorization did not result in a noticeable decrease in peak catalytic current until Congo red concentration up to 900 mg l⁻¹. Long-term decolorization of Congo red resulted in change in catalytic active site of anode biofilm.     

Blanket-like Bi2MoO6 coated on TiO2 NTA: Solvothermal construction and the enhanced photocatalytic hydrogen generation performance

Photocatalytic water splitting for hydrogen production was recognized as an effective strategy to obtain renewable energy for solving the environmental pollution and resource shortage crisis. Herein, we explored the solvothermal deposition method to successfully prepare blanket-like Bi₂MoO₆ coated on TiO₂ nanotube arrays (TiO₂ NTA/Bi₂MoO₆), and the TiO₂ NTA/Bi₂MoO₆ photocatalyst showed outstanding visible light-driven photocatalytic water splitting capacity, and the hydrogen evolution rate achieved 129.26 μmol h^-1 cm^-2. Moreover, the sample also exhibited high photocatalytic pollutant decomposition performance. The remarkable photocatalytic performance was attributed to the synergistic effect of Bi₂MoO₆ and TiO₂ NTA in the matched energy band location for solar absorption and carrier transportation. The synthesis and photocatalytic water splitting of Bi₂MoO₆/TiO₂ NTA could afford the reproducible lesson for novel resource utilization of semiconductor photocatalysts.     

Production of electricity from the treatment of continuous brewery wastewater using a microbial fuel cell

A single air-cathode microbial fuel cell (MFC) was constructed, carbon fiber was used as anode and continuous brewery wastewater as substrate. The MFC displayed a maximum power of 24.1 W m⁻³ (669 mW m⁻²) and an internal resistance of 23.3 Ω running on raw wastewater (chemical oxygen demand (COD) = 1501 mg L⁻¹). The effect of phosphate buffer solution (PBS) addition and substrate concentration of wastewater on the performance of MFC was demonstrated. Data showed that both PBS addition and increase of substrate concentration had a favorable effect on the electrochemical performance and substrate removal efficiency of the MFC. However, it can be concluded from the polarization curve that MFC operated under raw brewery wastewater had a relatively low internal resistance, which resulted in a favorable performance of the MFC compared with other MFCs using raw wastewater. Thus it is feasible and sustainable in nature because of the utilization of raw wastewater as substrate for in situ power generation apart from treatment.     

用于废水处理及产能的微生物燃料电池研究进展

详细介绍了用于废水处理及产能的微生物燃料电池的工作原理和特点,并阐述微生物燃料电池相关的微生物、阴极、阳极、反应方式和底物的最新研究进展,提出今后研发的重点.     

Electricity generation with simultaneous wastewater treatment by a microbial fuel cell (MFC) with Cu and Cu–Au electrodes

Background: A microbial fuel cell (MFC) consisting of anaerobic and aerobic chambers separated by a salt‐agar slab was used for electricity generation with simultaneous wastewater treatment where copper and gold covered copper wires were used as anode and cathode, respectively. The electrons produced from degradation of carbohydrates in anaerobic chamber traveled through the copper wire generating electricity and the protons were transferred from cathode to anode through the salt‐agar slab. Variation of the current intensity (mA) and the electrical power (mW) were investigated as function of the surface area of anode and also the chemical oxygen demand (COD) content of the synthetic wastewater. Results: The generated power density (mW m^?2) increased with increasing surface area of the electrodes and also with the COD content of the wastewater. Both the current intensity (mA) and the power generated (mW) increased with time and reached maximum levels at the end of batch operation. More than 80% COD removal was achieved in the aerobic chamber with an electricity generation of 2.9 mW m^?2 when the initial COD content was 6000 mg l^?1. Conclusion: The MFC configuration and the use of Cu and Cu‐Au electrodes instead of graphite were proven to be effective for electricity generation with simultaneous wastewater treatment. The electrical current (0.24 mA) and power (2.9 mW m^?2) obtained in our microbial fuel cell are comparable with the literature studies utilizing salt bridge. The microbial fuel cell developed in this study can be improved further to yield higher power generations by modifications. Copyright © 2007 Society of Chemical Industry     

微生物燃料电池技术及其影响因素研究进展

微生物燃料电池(Microbial fuel cell,MFC)作为一种绿色能源技术,通过微生物的氧化代谢作用将废水中的有机质降解的同时产生电能.然而,其相对较低的产电效率限制了MFC的工业化应用.该文介绍了影响MFC性能的诸多因素,如设备的构型限制、电极材料、阳极底物、阳极微生物和质子交换膜等,提出优化MFC的设计,提高MFC的产电性能,降低投入成本可解决MFC产业化应用的弊端,并对未来MFC的发展方向进行了展望.