Mechanism of Simultaneous Nitrogen Removal and Electricity Generation by Microbial Fuel Cell

The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The microorganisms growing on the electrodes and bioflocs could transfer electrons by direct contact and intermediaries respectively.The electrode biofilms and bioflocs were dominant in different functional spaces,and played a synergistic role in the process of contaminant removal,but showed a certain competitive relationship in the process of electricity generation.This study can provide a theoretical basis for the development of a new low-consumption wastewater treatment technology and promote technological innovation in wastewater treatment.

Electricity generation during wastewater treatment by a microbial fuel cell coupled with constructed wetland

A membrane-less constructed wetland microbial fuel cell （CW-MFC） is constructed and operated under continuous flow with a hydraulic retention time （HRT） of 2 d. Fed with glucose, the CW-MFC generates a stable current density of over 2 A/m3 with a resistor of 1 kΩ and has a chemical oxygen demand （COD） removal efficiency of more than 90% after the startup of 2 to 3 d. A series of systems with the electrode spacings of 10, 20, 30 and 40 cm are compared. It is found that the container with the electrode spacing of 20 cm gains the highest voltage of 560 mV, the highest power density of 0. 149 W/m 3, and the highest Coulombic efficiency of 0.313%. It also has the highest COD removal efficiency of 94. 9%. In addition, the dissolved oxygen （DO） concentrations are observed as the lowest level in the middle of all the CW-MFC reactors. The results show that the more COD is removed, the greater power is generated, and the relatively higher Coulombic efficiency will be achieved. The present study indicates that the CW-MFC process can be used as a cost-effective and environmentally friendly wastewater treatment with simultaneous power generation.

Changes in the microbial community structure and diversity during the electricity generation process of a microbial fuel cell with algal-film cathode

A two-chamber microbial fuel cell(MFC)with algal-film cathode was constructed.It showed good electric-generating performance with three electric-generating stages:start-up,development,and stable.An average output voltage reached~0.412 V during the stable period.A maximum power density during continuous operation was 19.76 mW/m^(2).Bacterial samples were collected from the anode in the three stages(A1,A2,and A3),and their community structure and diversity were analyzed using Illumina MiSeq high-throughput sequencing technology.A total of 4238 operational taxonomic units were identified based on the number of taxa.At the phylum level,Proteobacteria and Bacteroidetes played a dominant role in the three stages and increased significantly during electricity generation.Compared with A1,the relative abundances of Proteobacteria in A2 and A3 increased by 23.30%and 32.06%,respectively,whereas those of Bacteroidetes in A2 and A3 increased by 5.56%and 14.50%,respectively.At the genus level,there were differences in the composition of bacterial communities among the three stages.Acinetobacter and Chlorobium became the dominant genera in A2,replacing Nitrospira and norank_f__Saprospiraceae in A1,and Sphingobacterium and Ochrobactrum became the dominant genera in A3.According to the sample cluster and principal component analyses,A1 was clustered into one class,and A2 and A3 were clustered into a second class.This work revealed bacterial community succession at the anode of an algal-film cathode MFC during the electricity generation process,which provides a theoretical basis for the subsequent promotion of electricity generation by algal-film cathode MFCs.

Feasible design for electricity generation from Chlorella vulgaris using convenient photosynthetic conditions

Many recent studies are concerned with low cost,easy to handle and alternative renewable energy as a feasible solution for the upcoming crisis of energy shortage.Microalgae are unicellular entities the can only depend on CO_(2),water and solar power to cover their nutritional needs.The current study is concerned with using algal cells in a polymeric hydrogel,as a cheap source of energy for electricity generation.Chlorella vulgaris has been proved to be a promising algal species for electricity generation,as compared with Micractinium reisseri.PVA hydrogel has been used for the immobilization of both algal species in order to protect them from the adverse surrounding conditions in addition to its ability to slowly release the required water molecules according to needs.Under these conditions,C.vulgaris showed the ability to generate 60 mV compared with 15 mV generated by M.reisseri.Scanning electron micrographs showed nano-threads that bind the C.vulgaris cells to each other,indicating the ability of algae to create nanowires that facilitate the electron transfer among algal cells and from cells to the nearest electrode.However,we would expect an increase in the produced potential with simultaneous amendment of environmentally polluted water,such as sewage or waste water.Both of FTIR and raman spectroscopy proved the presence of the characteristic groups of PVA hydrogel and proved the proper integration of the algal cells inside the hydrogel cavities.

Combining biological denitrification and electricity generation in methane-powered microbial fuel cells

Methane has been demonstrated to be a feasible substrate for electricity generation in microbial fuel cells(MFCs)and denitrifying anaerobic methane oxidation(DAMO).However,these two processes were evaluated separately in previous studies and it has remained unknown whether methane is able to simultaneously drive these processes.Here we investigated the co-occurrence and performance of these two processes in the anodic chamber of MFCs.The results showed that methane successfully fueled both electrogenesis and denitrification.Importantly,the maximum nitrate removal rate was significantly enhanced from(1.4±0.8)to(18.4±1.2)mg N/(L·day)by an electrogenic process.In the presence of DAMO,the MFCs achieved a maximum voltage of 610 mV and a maximum power density of 143±12 mW/m^(2).Electrochemical analyses demonstrated that some redox substances(e.g.riboflavin)were likely involved in electrogenesis and also in the denitrification process.High-throughput sequencing indicated that the methanogen Methanobacterium,a close relative of Methanobacterium espanolae,catalyzed methane oxidation and cooperated with both exoelectrogens and denitrifiers(e.g.,Azoarcus).This work provides an effective strategy for improving DAMO in methane-powered MFCs,and suggests that methanogens and denitrifiers may jointly be able to provide an alternative to archaeal DAMO for methane-dependent denitrification.

Enhanced nitrate reduction in water by a combined bio-electrochemical system of microbial fuel cells and submerged aquatic plant Ceratophyllum demersum

High nitrate(NO_3^-)loading in water bodies is a crucial factor inducing the eutrophication of lakes.We tried to enhance NO_3^-reduction in overlying water by coupling sediment microbial fuel cells(SMFCs)with submerged aquatic plant Ceratophyllum demersum.A comparative study was conducted by setting four treatments:open-circuit SMFC(Control),closed-circuit SMFC(SMFC-c),open-circuit SMFC with C.demersum(Plant),and closed-circuit SMFC with C.demersum(P-SMFC-c).The electrochemical parameters were documented to illustrate the bio-electrochemical characteristics of SMFC-c and P-SMFC-c.Removal pathways of NO_3^- in different treatments were studied by adding quantitative^(15)NO_3^- to water column.The results showed that the cathodic reaction in SMFC-c was mainly catalyzed by aerobic organisms attached on the cathode,including algae,Pseudomonas,Bacillus,and Albidiferax.The oxygen secreted by plants significantly improved the power generation of SMFC-c.Both electrogenesis and plants enhanced the complete removal of NO_3^- from the sediment–water system.The complete removal rates of added^(15)N increased by 17.6% and 10.2% for SMFC-c and plant,respectively,when compared with control at the end of experiment.The electrochemical/heterotrophic and aerobic denitrification on cathodes mainly drove the higher reduction of NO_3^- in SMFC-c and plant,respectively.The coexistence of electrogenesis and plants further increased the complete removal of NO_3^- with a rate of 23.1%.The heterotrophic and aerobic denitrifications were simultaneously promoted with a highest abundance of Flavobacterium,Bacillus,Geobacter,Pseudomonas,Rhodobacter,and Arenimonas on the cathode.

Performance and recent improvement in microbial fuel cells for simultaneous carbon and nitrogen removal: A review

Microbial fuel cells（MFCs） have become a promising technology for wastewater treatment accompanying electricity generation. Carbon and nitrogen removal can be achieved by utilizing the electron transfer between the anode and cathode in an MFC. However,large-scale power production and high removal efficiency must be achieved at a low cost to make MFCs practical and economically competitive in the future. This article reviews the principles, feasibility and bottlenecks of MFCs for simultaneous carbon and nitrogen removal, the recent advances and prospective strategies for performance improvement, as well as the involved microbes and electron transfer mechanisms.

Sediment microbial fuel cell with floating biocathode for organic removal and energy recovery

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.

Effect of air-exposed biocathode on the performance of a Thauera-dominated membraneless single-chamber microbial fuel cell (SCMFC)

To investigate the effect of air-exposed biocathode（AEB） on the performance of singlechamber microbial fuel cell（SCMFC）, wastewater quality, bioelectrochemical characteristics and the electrode biofilms were researched. It was demonstrated that exposing the biocathode to air was beneficial to nitrogen removal and current generation. In Test 1 of 95%AEB, removal rates of ammonia, total nitrogen（TN） and chemical oxygen demand（COD）reached 99.34% ± 0.11%, 99.34% ± 0.10% and 90.79% ± 0.12%, respectively. The nitrogen removal loading rates were 36.38 g N/m3/day. Meanwhile, current density and power density obtained at 0.7 A/m3 and 104 m W/m3 respectively. Further experiments on opencircuit（Test 2） and carbon source（Test 3） indicated that this high performance could be attributed to simultaneous biological nitrification/denitrification and aerobic denitrification, as well as bioelectrochemical denitrification. Results of community analysis demonstrated that both microbial community structures on the surface of the cathode and in the liquid of the chamber were different. The percentage of Thauera, identified as denitrifying bacteria, maintained at a high level of over 50% in water, but decreased gradually in the AEB. Moreover, the genus Nitrosomonas, Alishewanella, Arcobacter and Rheinheimera were significantly enriched in the AEB, which might contribute to both enhancement of nitrogen removal and electricity generation.

Nitrite pre-treatment of dewatered sludge for microbial fuel cell application

The effect of pre-treatment of dewatered sludge using different nitrite concentrations and p H for microbial fuel cell(MFC) application was investigated. The results show that the addition of nitrite was feasible to increase the solubilization rate of the sludge and may reduce mass transfer limitation at the anode. This helped the MFC to reach higher voltage and to generate more power. The higher free nitrous acid(FNA) concentration under the acidic condition helped to increase sludge solubilization. However, under an alkaline condition, during which the FNA concentration was relatively low, the solubilization of the sludge was higher. The highest voltage and power density produced was 390 mV and 153 mW/m^2, respectively, with the addition of nitrite at 100 mg-N/L and pH 9. Furthermore,it was found that elevated levels of FNA could inhibit electrogenic bacteria thus reducing power generation.

Trickling filter in a biocathode microbial fuel cell for efficient wastewater treatment and energy production

Aiming to reduce the energy input, oxygen supply by trickling filter was employed in a biocathode microbial fuel cell(MFC) to examine its performance of electricity production and sewage treatment. During batch operation, trickling MFC(TMFC) could start and aerate effectively(DO>3.60 mg/L). During continuous operation, TMFC produced a maximum current density of 71.8 A/m^3 and maximum power density of 26.2 W/m^3 under the hydraulic retention time(HRT) of 10 h. By increasing the HRT to 15 h, 90.6% of COD and 99.0% of ammonia in simulated domestic sewage were efficiently removed and the maximum power density was 19.4 W/m^3. Continuous purification of real municipal wastewater achieved 85.9% of COD removal rate and 91.6%of ammonia removal rate. Sequencing result of biocathodic microorganisms indicated that it consisted of four major classes and the dominant class was γ-proteobacteria, which accounted for up to 84.38%. The dominant genus was Acinetobacter, which accounted for 57.81%. The phylogenetic tree showed different relationships among the 19 species of biocathode microorganisms and the predominant species was Acinetobacter calcoaceticus.

产电微生物与微生物燃料电池研究进展

微生物燃料电池可以同时进行废水处理和生物发电,作为一种新型的能源回收技术得到人们的广泛关注。详细评述了微生物燃料电池的产电机制,对微生物燃料电池的构造进行了归纳,并展望了微生物燃料电池的应用前景。

微生物燃料电池技术的研究进展

针对MFC产电性能低下的现状,结合其发展趋势,综述了MFC工作原理及电子转移机制,分析了MFC在质子交换膜和电极材料改善等方面未来发展的主要方向及面临的问题,为提高MFC的产电性能和除污能力提供新思路。

微生物燃料电池中产电微生物的研究进展

微生物燃料电池(Microbial fuel cell,MFC)作为一种新型的环境治理和能源技术,目前已得到研究者们的广泛关注。微生物燃料电池是一种利用微生物将有机物中的化学能转化成电能的装置,产电微生物作为生物催化剂,对微生物燃料电池的发展至关重要。不同种类的产电微生物,其电子转移机制与能力有所差异,直接影响MFC的产电性能,从而决定MFC在工程实践中的性能与应用。任何含有大量微生物的废水、污泥、沉积物都可以作为产电微生物的筛选来源,尝试从不同环境条件下分离筛选高效产电微生物有望促进MFC的进一步完善,从而加速其在环境中的应用。通过对微生物燃料电池的发展、产电微生物种类及其电子传递机制等进行总结分析,综述了MFC中产电微生物的最新研究进展,包括产电微生物的筛选方法、种类以及技术研究等,最后展望了今后在产电微生物方面的主要研究方向及MFC的发展前景,以期为产电微生物的的筛选和应用奠定相应的理论基础及提供思路。

可降解苯酚的产电芽孢杆菌WL027的分离筛选及其产电机制初探

以含苯酚的生活污水为底物构建微生物燃料电池(microbial fuel cell,MFC),从处于稳定期的MFC阳极中分离筛选获得一株可降解苯酚的产电菌WL027。对菌株WL027的生理生化鉴定表明,该菌为蜡样芽孢杆菌。同时,对菌株WL027的产电性和苯酚降解情况进行了初步探讨。结果表明:菌株WL027具有电化学活性,产电期主要集中在菌株生长的稳定期;将菌株WL027接种到MFC中,MFC的最大电压较起始电压增加了179mV,库仑效率为64.25%,苯酚降解率为68.62%;菌株WL027在产电过程中胞内和胞外核黄素质量浓度分别为6.10×10^(-3)和1.32×10^(-2) mg/L;在已处于稳定期的MFC中加入核黄素,电压升高了18mV。猜测菌株WL027可能通过分泌核黄素来促进电子在微生物中传递。

泥土原电池发电及其在路灯上的应用研究

通过对近几年该领域相关资料的研究,分析土壤微生物燃料电池的产电机理及其影响因素,明确研制出新型土壤微生物燃料电池的重要途径是获得高效廉价的电极材料和膜材料,探求使改良后的土壤微生物燃料电池的产出电量足够供应小型路灯使用,并对其研究前景进行展望。

一株以喹啉为燃料的产电假单胞菌(Pseudomonas sp.)Q1的特性研究

微生物燃料电池(Microbial fuel cell,MFC)阳极微生物的种类和作用机制对MFC的产电性能有着重要影响.从稳定运行了210d,以200mg·mL-1喹啉为燃料的MFC阳极室分离得到一株革兰氏阴性菌,命名为Q1,其16S rRNA基因序列与Pseudomonas citronellolisDSM50332T的同源性为96.9%,属于假单胞菌属(Pseudomonassp.).循环伏安法及构建纯菌MFC方法的测定结果均表明Q1具电化学活性.菌株Q1能利用单一喹啉或喹啉和葡萄糖混合燃料产电.在本试验所用浓度范围内,增加葡萄糖浓度,菌株Q1对应的最高输出电压增加,增加喹啉浓度菌株Q1的产电性能则降低,研究表明,菌株Q1库仑量和库仑效率达到最高时(分别为18.65C和36.56%),存在一个最佳喹啉与葡萄糖浓度比1∶3.在MFC中喹啉的降解效果优于普通厌氧培养,葡萄糖对菌株Q1降解喹啉有促进作用,以喹啉和葡萄糖为混合燃料24h对喹啉的去除率达99.53%,优于以单一喹啉为燃料的情况.循环伏安法和不同更换基质方式试验表明,附着在电极上的菌株Q1对产电起主要作用,Q1的溶解态代谢产物对产电过程起电子介体的作用.

微生物燃料电池及其在废水/废弃物处理中的应用

微生物燃料电池(microbial fuel cells,MFC)作为一项解决环境污染同时开发可再生能源的新技术,近年来受到国内外研究者广泛关注。基于MFC工作原理,全面归纳了其典型的高效产电菌,并从阳极氧化、阴极还原两方面重点探讨了其在处理废水/废弃物的应用实例及发展潜力,最后从3个方面对MFC在环境领域的应用前景作了展望。

一株耐盐产电菌Shewanella algae E-1的分离及其产电特性分析

【背景】产电微生物的种类和电化学活性机制对微生物燃料电池的产电性能有着重要的影响。【目的】从海水中分离获得一株耐盐产电微生物,研究其产电特性并鉴定种属信息。【方法】以取自南海的海水为接种液启动并运行阳极液中含有不同盐浓度的微生物燃料电池,从富集的阳极生物膜上分离得到一株纯培养的微生物菌株,命名为E-1。通过接种于阳极液中添加不同盐浓度的微生物燃料电池中对其产电特性进行分析,并利用形态学观察、Biolog分析和16SrRNA基因序列比对相结合的方法进行种属鉴定。【结果】菌株E-1在无外源添加和外源添加6.6%NaCl条件下产生的功率密度分别为51.69 m W/m2和26.56 m W/m2,这与其良好的耐盐能力相关。菌株E-1被鉴定为海藻希瓦氏菌(Shewanella algae),表现出多样的底物利用能力,生长的温度范围为25-40°C,pH范围为5.0-10.0。【结论】这是首次对Shewanella algae种内微生物产电性能及其在微生物燃料电池中应用的报道,丰富了产电微生物的多样性,菌株E-1能够在较高盐浓度条件下表现出良好的产电性能,为微生物燃料电池在海水资源化处理方面的应用提供新的实验材料。