Effect of endogenous hydrogen utilization on improved methane production in an integrated microbial electrolysis cell and anaerobic digestion： Employing catalyzed stainless steel mesh cathode

Improving the production of methane, while maintaining a significant level of process stability, is the main challenge in the anaerobic digestion process. Recently, microbial electrolysis cell(MEC) has become a promising method for CO_2 reduction produced during anaerobic digestion(AD) and leads to minimize the cost of biogas upgrading technology. In this study, the MEC-AD coupled reactor was used to generate and utilize the endogenous hydrogen by employing biocompatible electrodeposited cobalt-phosphate as catalysts to improve the performance of stainless steel mesh and carbon cloth electrodes. In addition, the modified version of ADM1 model(ADM1 da) was used to simulate the process. The result indicated that the MEC-AD coupled reactor can improve the CH_4 yield and production rate significantly. The CH_4 yield was enhanced with an average of 48% higher than the control. The CH_4 production rate was also increased 1.65 times due to the utilization of endogenous hydrogen.The specific yield, flow rate, content of CH_4, and p H value were the variables that the model was best at predicting(with indexes of agreement: 0.960/0.941, 0.682/0.696, 0.881/0.865, and 0.764/0.743) of the process with SSmeshes 80/SS-meshes 200, respectively. Employing the catalyzed SS mesh cathode, in the MEC-AD coupled reactor, could be an effective approach to generate and facilitate the utilization of endogenous hydrogen in anaerobic digestion of CH_4 production technology, which is a promising and feasible method to scale up to the industrial level.

Microbial Electrolysis Cells for Hydrogen Production

Microbial electrolysis cells(MECs)present an attractive route for energy-saving hydrogen(H2)production along with treatment of various wastewaters,which can convert organic matter into H2 with the assistance of microbial electrocatalysis.However,the development of such renewable technologies for H2 production still faces considerable challenges regarding how to enhance the H2 production rate and to lower the energy and the system cost.In this review,we will focus on the recent research progress of MEC for H2 production.First,we present a brief introduction of MEC technology and the operating mechanism for H2 production.Then,the electrode materials including some typical electrocatalysts for hydrogen production are summarized and discussed.We also highlight how various substrates used in MEC affect the associated performance of hydrogen generation.Finally we presents several key scientific challenges and our perspectives on how to enhance the electrochemical performance.

Degradation Pathway of Benzothiazole and Microbial Community Structure in Microbial Electrolysis Cells

In this study, benzothiazole was entirely mineralized by an up-flow internal circulation microbial electrolysis reactor. The bioelectrochemical system was operated at ambient temperature under continuous-flow mode. The analysis of metabolite which was extracted by HPLC-MS from the bioreactor indicated that benzothiazole derivative ( BTH ) was firstly converted into 2-hydroxybenzothiazole in the microbial electrolysis cell (MEC) and then mineralized within three steps, i.e., the fracture of thiazole-ring through a series of oxidation and hydrolysis, the deamination and hydroxylation of 2-aminobenzenesulfonic acid, and the mineralization of various carboxylic acids to CO2 and H2O. Bacterial community analysis indicated that the applied electric field could selectively enrich certain species and the dominate bacteria on the electrodes belonged to Proteobacteria, Bacteroidetes, and Firmicutes. Results show that MEC can improve the degradation efficiency of BTH in wastewater, enable the microbiological reactor to satisfy the requirements of high loading rate, thereby fulfilling the scale-up of whole process in the future.

Enhanced straw fermentation process based on microbial electrolysis cell coupled anaerobic digestion

The low quality and yield of methane severely hinder the industrial application of straw biogas fermentation, and no effective solution has been found so far. In this study, a novel method was developed when a microbial electrolysis cell(MEC) was coupled with normal anaerobic fermentation to enhance methane yield and purity. The fermentation process achieved a methane purity of more than 85%, which is considerably higher than that of previously published reports. With microbial stimulation and an electric current, the degradation of fibers has been greatly enhanced. The MEC system substantially improved the yield and purity of biogas, bringing a new path to the synthesis of methane by carbon dioxide and hydrogen ions in solution under electron irradiation. Electrochemical index analysis showed extra methane synthesis, due to the external circuit electron transfer. The results of the gas chromatography and solid degradation rate showed that the carbon source of extra methane was CO_(2) produced during normal fermentation and additional volatile solid degradation. These results show that the MEC considerably enhanced the quality and yield of methane in the straw fermentation process, providing insights into normal anaerobic fermentation.

Fuzzy logic controller implementation on a microbial electrolysis cell for biohydrogen production and storage

This work presents the implementation of fuzzy logic control(FLC) on a microbial electrolysis cell(MEC).Hydrogen has been touted as a potential alternative source of energy to the depleting fossil fuels. MEC is one of the most extensively studied method of hydrogen production. The utilization of biowaste as its substrate by MEC promotes the waste to energy initiative. The hydrogen production within the MEC system, which involves microbial interaction contributes to the system's nonlinearity. Taking into account of the high complexity of MEC system, a precise process control system is required to ensure a wellcontrolled biohydrogen production flow rate and storage application inside a tank. Proportionalderivative-integral(PID) controller has been one of the pioneer control loop mechanism. However, it lacks the capability to adapt properly in the presence of disturbance. An advanced process control mechanism such as the FLC has proven to be a better solution to be implemented on a nonlinear system due to its similarity in human-natured thinking. The performance of the FLC has been evaluated based on its implementation on the MEC system through various control schemes progressively. Similar evaluations include the performance of Proportional-Integral(PI) and PID controller for comparison purposes. The tracking capability of FLC is also accessed against another advanced controller that is the model predictive controller(MPC). One of the key findings in this work is that the FLC resulted in a desirable hydrogen output via MEC over the PI and PID controller in terms of shorter settling time and lesser overshoot.

Study on Biological Pathway of Carbon Dioxide Methanation Based on Microbial Electrolysis Cell

Realization of CO_(2) resource utilization is the main development direction of CO_(2) reduction.The CO_(2) methana-tion technology based on microbial electrolysis cell(MEC)has the characteristics of ambient temperature and pressure,green and low-carbon,which meets the need of low-carbon energy transition.However,the lack of the system such as the change of applied voltage and the reactor amplification will affect the methane production efficiency.In this research,the efficiency of methane production with different applied voltages and different types of reactors was carried out.The results were concluded that the maximum methane production rate of the H-type two-chamber microbial electrolysis cells(MECs)at an applied voltage of 0.8 V was obtained to be 1.15 times higher than that of 0.5 V;under the same conditions of inoculated sludge,the reactor was amplified 2.5 times and the cumulative amount of methane production was 1.04 times higher than the original.This research can provide a theoretical basis and technical reference for the early industrial application of CO_(2) methanation tech-nology based on MEC.

Hydrogen production performance of the non⁃platinum⁃based MoS_(2)/CuS cathode in microbial electrolytic cells

MoS_(2)/CuS composite catalysts were successfully synthesized using a one-step hydrothermal method with sodium molybdate dihydrate,thiourea,oxalic acid,and copper nitrate trihydrate as raw materials.The hydrogen pro-duction performance of MoS_(2)/CuS prepared with different molar ratios of Mo to Cu precursors(n_(Mo)∶n_(Cu))as cathodic catalysts was investigated in the two-chamber microbial electrolytic cell(MEC).X-ray diffraction(XRD),X-ray pho-toelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscope(TEM),linear scanning voltammetry(LSV),electrochemical impedance analysis(EIS),and cyclic voltammetry(CV)were used to characterize the synthesized catalysts for testing and analyzing the hydrogen-producing performance.The results showed that the hydrogen evolution performance of MoS_(2)/CuS-20%(nMo∶nCu=5∶1)was better than that of platinum(Pt)mesh,and the hydrogen production rate of MoS_(2)/CuS-20%as a cathode in MEC was(0.2031±0.0237)m^(3)_(H_(2))·m^(-3)·d^(-1) for 72 h at an applied voltage of 0.8 V,which was slightly higher than that of Pt mesh of(0.1886±0.0134)m^(3)_(H_(2))·m^(-3)·d^(-1).The addition of a certain amount of CuS not only regulates the electron transfer ability of MoS_(2) but also increases the density of active sites.

铝电解企业制造执行系统(MES)的应用开发

运用MES理论对青海省某大型铝电解企业的现状进行分析,判断其制造执行系统的需求,有针对性地开发电解铝制造执行系统,实现控制系统和管理信息系统的一体化集成,使企业达到现代化管理水平。

铝电解企业MES整体分析及其构建

分析流程制造企业面临的问题和铝电解企业生产过程,利用MES理论构建现代化的制造执行系统,实现电解铝生产数字化动态管理,提高生产管理水平.

Approximate Analytical Expressions for the Concentrations of Acetate and Methane in the Microbial Electrochemical Cell

Mathematical modeling of microbial electrochemical cells (MXCs) for both microbial fuel cell and microbial electrolysis cell is discussed. The model is based on the system of reaction diffusion of reaction-diffusion equation containing a non-linear term related to substrate consumption rates by electrogeneic and methanogenic microorganism in the bioflim. This paper presents the approximate analytical method to solve the non-linear differential equation that describes the diffusion coupled with acetate (substrate) consumption rates. Simple analytical expressions for the concentrations of acetate and methane have been derived for all experimental values of bulk concentration, distributions of microbial volume fraction, local potential in the biofilm and biofilm thickness. In addition, sensitivity of the parameters on concentrations is also discussed. Our analytical results are also validated with the numerical results and limiting cases results. Further, a graphical procedure for estimating the kinetic parameters is also suggested.

环境微生物对水体中微囊藻毒素降解机制的研究进展

近年来,全球气候变暖和水体富营养化加剧导致蓝藻水华污染严重,而大部分蓝藻水华暴发后产生的微囊藻毒素(Microcystins,MCs)极具危害性,对人类健康和水生生态系统构成威胁。有效控制和去除水体中的MCs已成为当前亟需解决的一项难题。现有研究表明,微生物降解MCs具有高效和环保的治理效益。因此,本文综述了MCs的产生、结构和毒性危害,并着重介绍了国内外学者在微生物降解MCs的酶促降解途径、降解基因和降解酶领域的研究进展;此外,还分析了微生物降解菌在水体生态修复中的潜在应用,并展望了对MCs的非mlr降解途径机制、优化表达MCs降解酶、构建高效双功能降解菌等未来研究方向,旨在为深入研究MCs微生物降解机制并有效改善全球水体中MCs污染现状提供新思路。

初始pH调控对MEC脱硫性能的影响及其微生物作用机制

采用微生物电解池(MEC)工艺,在阳极电活性微生物的协同作用下实现硫化物的脱除,是沼气脱硫新工艺和研究热点。针对长期运行的脱硫MEC工艺,由于非特异性阳离子竞争使阳极产生的质子向阴极转移受阻,造成MEC脱硫效率低、稳定运行难,本研究采用不同初始pH调控脱硫MEC的质子平衡,通过脱硫性能、电化学性能和微生物动力学解析,阐明pH调控对MEC脱硫性能的影响和微生物作用机制。结果表明,初始pH在7~9时均可形成稳定且具有高效脱硫功能的阳极生物膜,最大电流密度相近,脱硫效率均达95%以上,COD去除率80%以上。与初始pH为8、9相比,初始pH为7时,脱硫过程pH波动最小,MEC运行稳定,S^(2-)去除最高达100%;阳极生物膜的氧化还原峰最显著,质子与电子转移速率加快;优势微生物Thiomonas与Desulfovibrio丰度更高,主要参与硫化物的氧化脱除。可见,通过脱硫MEC阳极室初始pH的调控,可有效提高MEC脱硫工艺性能和运行稳定性,为沼气微生物电化学脱硫的应用提供技术支撑。

微生物-电极修饰及影响电合成转化CO_(2)过程的研究进展

微生物电合成(microbial electrosynthesis,MES)是一种利用电活性微生物摄取胞外电子,将CO_(2)或有机废料转化为可再生化学品的技术。首先,文中阐述了电极的改性方式,碳基材料以其多样的形态、优异的化学稳定性和高比表面积等优点,在电极改性中发挥着重要作用,其主要是通过提供更多的微生物附着点和增强电子传递效率改善MES;而非碳基材料如金属材料等,因其优异的导电性和催化活性,则被广泛用于提升电极性能,其作用机制在于加速电极上的催化反应和促进特定产品的生成。其次,从电活性微生物角度入手,揭示了在电极材料修饰和微生物细胞修饰上的共同点都是能够提高微生物的电子传递能力,不同点在于微生物细胞修饰可以直接作用于微生物的生理和遗传特性,以增强其电子传递能力和底物转化效率。此外,分析了纳米材料与高附加值产品之间的关系,认为合理选择和制备电极材料及微生物细胞修饰策略,对于提高MES系统的效率和产物选择性至关重要。最后,对MES技术面临的挑战和未来的研究方向进行了展望。

Efficient degradation of aqueous dichloromethane by an enhanced microbial electrolysis cell:Degradation kinetics,microbial community and metabolic mechanisms

Dichloromethane(DCM)has been listed as a toxic and harmful water pollutant,and its re moval needs attention.Microbial electrolysis cells(MECs)are viewed as a promising alterna tive for pollutant removal,which can be strengthened from two aspects:microbial inocula tion and acclimation.In this study,the MEC for DCM degradation was inoculated with the ac tive sludge enhanced by Methylobacterium rhodesianum H13(strain H13)and then acclimated in the form of a microbial fuel cell(MFC).Both the introduction of strain H13 and the initi ation in MFC form significantly promoted DCM degradation.The degradation kinetics were fitted by the Haldane model,with V_(max),K_(h),K_(i)and v_(max)values of 103.2 mg/L/hr,97.8 mg/L268.3 mg/L and 44.7 mg/L/hr/cm^(2),respectively.The cyclic voltammogram implies that DCM redox reactions became easier with the setup of MEC,and the electrochemical impedance spectrogram shows that the acclimated and enriched microbes reduced the charge transfe resistance from the electrode to the electrolyte.In the biofilm,the dominant genera shifted from Geobacter to Hyphomicrobium in acclimation stages.Moreover,Methylobacterium played an increasingly important role.DCM metabolism mainly occurred through the hydrolytic glutathione S-transferase pathway,given that the gene dcmA was identified rather than the dhlA and P450/MO.The exogenous electrons facilitated the reduction of GSSG,directly o indirectly accelerating the GSH-catalyzed dehalogenation.This study provides support fo the construction of an efficient and stable MEC for DCM removal in water environment.

磁铁矿作用下DvH阴极生物膜的响应及转录组分析

本研究通过构建Desulfovibrio vulgaris Hildenborough(DvH)生物阴极,探究磁铁矿纳米颗粒(MNPs)作用下其生物膜的响应机制.结果发现,相较于无MNPs添加组,MNPs介导下的DvH生物阴极的SO_(4)^(2-)-S~(2-)转化率由6.8%提升至37.9%,周期电荷量提升了11.5%.线性伏安扫描结果显示,在0~-0.81V电势范围内,MNPs添加组阴极电流均高于对照组,说明MNPs可以增强阴极生物膜电催化活性.DvH阴极生物膜的比较转录组结果表明,MNPs可通过促进与[FeFe]氢化酶、Hmc和ATP合成酶相关的基因的表达,促进DvH对氢气的利用和代谢;通过促进编码ATP硫酰化酶和腺苷酸硫酸还原酶这两种硫代谢关键酶的基因表达上调,提高SO_(4)^(2-)-S^(2)转化率;通过促进Flp/Tad菌毛组装和PEP-CTERM蛋白相关基因的表达上调,强化DvH在阴极的附着和成膜.研究结果可为微生物阴极电化学系统的高效构建提供新的理论依据.

利用微生物电解池法增强冷水鱼循环水养殖系统水质处理能力

为了解决传统曝气生物滤池对养殖废污水中氨氮和硝酸盐去除效率较低的问题,本文利用微生物电解池(MEC)法研究低温条件下不同碳源种类、电压强度对MEC系统化学需氧量(COD)、氨氮(NH_(3)-N)、硝氮(NO_(3)^(-)-N)、总氮(TN)和总磷(TP)的脱除效率,了解最优碳源和电压强度条件下微生物电解池强化淡水冷水鱼养殖系统的水处理能力并探讨其去除机理。结果表明:乙酸钠为碳源时,COD、NH_(3)-N、NO_(3)^(-)-N和TP去除率分别达到82.10%、87.56%、98.64%和73.64%;电压强度为0.30 V时,COD、NH_(3)-N、NO_(3)^(-)-N和TP去除率分别达到81.01%、73.15%、76.74%和83.97%。宏基因测序结果显示,在最佳碳源和电压强度条件下,属水平下的链霉菌属、假单胞菌属和伯克霍尔德菌属为微生物群落中主要的优势菌属;氮代谢通路涉及到的关键功能基因amoCAB、nxrAB、nirBD、nrfA和nifDHK等表明,MEC系统主要通过同步硝化反硝化路径进行氮去除代谢。

电解-微生物燃料电池耦合系统处理染料废水性能

构建电解-微生物燃料电池耦合系统处理偶氮染料废水,考察了该系统的运行性能。运行结果表明:电解池的最优运行电压为2.0 V,在此条件下,其对废水中重氮基团的破解和色度的去除效果最佳。该耦合系统对废水色度和COD的去除率分别可达到91.0%和86%,且能够输出电压(0.66±0.03)mV,产电性能良好。

微生物燃料电池处理含油废水研究进展

介绍了微生物燃料电池(MFC)的产电机理,总结了不同含油废水处理方法的特点以及微生物燃料电池对含油废水的处理效果。指出未来在含油废水处理领域MFC的发展重点是优化反应器性能,开发高效廉价的阴极催化剂,研究产电微生物与油类降解菌之间的协同作用,并阐明油类物质在MFC中的降解机理以及与传统的水处理工艺耦合使用,以最大限度的提高含油废水处理效果。

MoS_2/石墨烯复合阴极材料的制备及微生物电解池催化产氢性能

采用水热法合成了一系列MoS_2/石墨烯(Gr)复合物,并制成碳基复合电极.利用扫描电子显微镜、透射电子显微镜、线性扫描伏安法等手段对材料进行表征,研究了MoS_2/Gr电极作为微生物电解池(MEC)阴极的产氢性能.结果表明,MoS_2/Gr复合材料呈现三维层状结构,且负载在石墨烯上的MoS_2为无定形MoS_2.(NH_4)_2MoS_4和氧化石墨烯的最佳原料配比为1∶1,当滴涂量为1.5mg/cm^2时,电极的析氢催化能力最强.在MEC产氢实验中,MoS_2/Gr阴极MEC的平均产氢电流密度、产氢率、库仑效率、氢气回收率和阴极氢气回收率分别为(9.96±0.65)A/m^2,(0.424±0.041)m^3H_2/(m^3·d),(89.11±5.87)%,(70.47±6.78)%和(78.86±2.49)%,均高于Pt/C阴极MEC;其能量回收率也与后者相媲美.另外,MoS_2/Gr具有良好的长期稳定性,且价格便宜,适于实际应用.

金属钛粉的制备工艺

钛粉作为钛粉末冶金的主要原料,其品质及生产成本限制了钛及钛合金粉末冶金的发展。综述了机械合金化法、氢化脱氢法(HDH)、雾化法、金属热还原法、熔盐电解法制备钛粉的基本原理和工艺现状。新兴的生产技术有望降低钛粉生产成本,从而推动钛及钛合金粉末冶金的发展,扩大其应用范围。