基于混菌产电微生物燃料电池的最新研究进展

混菌微生物燃料电池(MFC)是直接利用环境中多种微生物附着于阳极而产电的方式,相对于纯菌MFC的前期菌种培养和富集,混菌电池的启动不仅省时且更节约成本,同时其抗环境冲击的能力也更强,电池稳定性更高。介绍了混菌MFC的最新研究现状,详细讨论了产电微生物的种类、电子传递机制、影响混菌MFC产电效能的主要因素,以及目前存在的问题等,并指出了混菌MFC的未来研究重点和方向。     

浸没式厌氧膜生物反应器的研发及其除污效能

为解决阻碍厌氧膜生物反应器应用的膜污染问题,开发了处理能力为20 m3/d的浸没式厌氧膜生物反应器,其内置40m2的旋转膜组件,并采用环形布水管路设计,以保证分离效果和布水的均匀性,并能够实现在线反冲洗.采用该反应器处理食品废水,在长达5个月的运行期间对有机物的去除率可达95%以上,出水COD < 50 mg/L;当膜组件旋转速度达250 r/min时,可获得最大稳定膜通量为20 L/(m2.h),且未进行CIP在线和离线清洗;在中温环境下甲烷产率可达55%以上,回收利用率高;与传统外置式膜生物反应器相比,则至少节能约32%     

微波协同低碱预处理对污泥MFC性能的影响

分别以原泥、微波预处理污泥和微波协同低碱预处理污泥为微生物燃料电池(MFC)的阳极底物,通过比较其产电性能和污泥泥质变化,考察微波协同低碱预处理技术对改善MFC污泥资源化效果的影响。结果表明,污泥经微波协同低碱预处理后,进一步提高了MFC的产电能力和污泥降解效果。微波协同低碱预处理组的稳定输出电压升至(610±10)m V(外阻R=500Ω),稳定时间延长至17 d;最大产电功率密度提高到14.90 W/m3;反应器运行23 d,对TCOD的去除率增至43.5%,库仑效率提高到6.59%。随着反应器的运行,以预处理污泥为底物的MFC,污泥SCOD浓度先下降后上升,而以原泥为底物时污泥SCOD浓度始终处于上升趋势;氨氮浓度随反应器运行先上升然后逐渐降低;污泥p H值一直下降,且微波协同低碱预处理组下降最多。     

低温条件下微生物对沉积物氮释放的影响研究

通过室内静态模拟实验,研究了沉积物中氮的释放特性。将反应器密封后自然达到厌氧状态,温度与水库底部相近（7～8℃）,进行未灭菌和灭菌两个系列对比试验,连续监测两个系列装置中NO3^-N、NO^2-N、NH4^＋-N、TN、DO和pH的变化,并对试验前后沉积物中的总氮含量进行测定。结果表明,未灭菌装置沉积物中总氮减少量明显多于灭菌装置,而上覆水中可监测总氮少于灭菌装置,说明在厌氧条件下氮元素会在微生物作用下从沉积物中释放出来,并通过反硝化和厌氧氨氧化等作用以气态形式释放出水体。试验前后对底泥表面的硝化、亚硝化、反硝化和氨化细菌的数量通过计数进行了比较,发现厌氧后反硝化细菌和氨化细菌明显增多,说明厌氧过程中对氮释放起主要作用的是反硝化细菌和氨化细菌。     

投加有机物提高ANAMMOX反应器脱氮效果的研究

往一套UASB生物膜厌氧氨氧化反应器中加入葡萄糖促使反应器内反硝化菌增殖,然后迫使增殖的反硝化菌进行厌氧氨氧化反应以提高反应器的脱氮效果。结果显示:在反应器进水中加入葡萄糖后,系统对亚硝酸盐氮的去除率迅速提高到90%,但对氨氮的去除率变化不大,显示出反应器内同时发生了反硝化反应和厌氧氨氧化反应;当进水中停止投加葡萄糖后,仅运行10d,系统对氨氮、亚硝酸盐氮和总氮的去除率就分别达到了90%、98%和91%,一个月后对总氮的去除率达到99%。可见,在特定环境下可迫使反硝化菌进行厌氧氨氧化反应。     

浸没式厌氧双轴旋转膜生物反应器的开发

针对浸没式厌氧膜生物反应器的膜污染问题,开发了一套内置双轴旋转膜组件的浸没式厌氧膜生物反应器.系统的容积为120 L,内装填平板超滤膜.膜组件采用双轴同向旋转,由膜旋转形成的湍流可减缓膜表面的浓差极化及凝胶层的形成,从而有效控制膜污染.与传统厌氧膜生物反应器相比,该工艺具有结构紧凑、除污效果好、能耗低和可大幅度减轻膜污染等优点.     

厌氧氨氧化与反硝化的协同作用特性研究

在已稳定运行7个月的自养脱硫反硝化反应器中成功富集厌氧氨氧化菌后,利用反硝化菌的不完全反硝化作用为厌氧氨氧化菌提供NO2--N。以NH4+-N、NO3--N和有机物为基质,研究厌氧氨氧化与反硝化的协同作用,并探讨了其最适协同作用条件。反应器的有效容积为2L,遮光放置,通过恒温水浴维持反应器内温度为(33±0.5)℃,并投加活性炭作为填料。结果表明,厌氧氨氧化菌能与反硝化菌共存,反应器可实现厌氧氨氧化与反硝化的协同作用,且最适协同作用条件是:COD/TN=1.46、pH=7.55。     

厌氧产酸反应器启动方法及过程特性研究

依据二相厌氧的理论,设计并启动酸化反应器,用啤酒废水处理的厌氧活性污泥接种驯化,采用化学法与容积负荷控制相结合的方法进行反应器的启动实验,实验中测得各阶段COD的变化及COD的去除效率。得到了二相厌氧反应器分相启动的方法和基本条件。从实验结果可以看出:在pH值4.5~6.0,温度在27±2℃;有机负荷从1 kg/m3.d~10 kg/m3.d缓慢增加的条件下,厌氧产酸反应器的启动比较容易。利用色谱-质谱联动仪分析厌氧产酸反应器进出水质的特性。结果表明:经厌氧酸化反应后,有机物的种类没有减少,相反增加了许多小分子的水解、酸化反应的中间产物,产酸反应器将大分子难降解化合物降解为易降解的酸性小分子化合物,可生化性有所提高。     

不完全厌氧技术用于棉针织印染废水处理的应用研究

通过不完全厌氧完全混合反应器(HCSTR)和不完全厌氧移动床反应器(HMBBR)的中试装置的连续运行,对棉针织印染废水不完全厌氧生物预处理工艺进行了研究,探讨了工艺条件对废水处理效果的影响。根据试验结果,设计完成了集反应-分离为一体的不完全厌氧反应器,处理规模为2000m3/d。运行的结果表明,各项指标达到设计要求。与现有混凝沉淀预处理工艺相比,不完全厌氧预处理技术运行成本下降60%,污泥产量下降75%,出水的生化性提高,BOD5/CODCr为0.35。     

ABR处理糖蜜酒精模拟废水的启动试验

为避免糖蜜酒精废水厌氧处理中硫酸盐还原菌(SRB)对产甲烷菌(MPB)的基质竞争性抑制,并消除硫化物对MPB的毒性作用,在30℃下,利用厌氧折流板反应器(ABR)对糖蜜酒精模拟废水进行了历时92d的启动试验。结果表明,采用低COD和低SO42-负荷启动,是ABR反应器成功启动的关键;成功启动后,各隔室出现明显的相分离(产酸还原硫酸盐相和生成硫单质产甲烷相)特征,说明在微氧/厌氧环境中,酸化菌(AB)可与SRB共存,无色硫细菌(CSB)可与MPB共存;在反应器的第4隔室生成大量单质硫颗粒,可以达到回收利用单质硫的目的。可见,采用ABR处理糖蜜酒精废水是完全可行的。     

Phosphorus release from sediments from Lake Carl Blackwell, Oklahoma

A laboratory study was conducted to determine the effects of anaerobic vs aerobic conditions, sterile vs non-sterile conditions and mixing on the release of soluble ortho-phosphate from sediments obtained from Lake Carl Blackwell, Oklahoma. Eight laboratory systems reflecting various combinations of the three environmental conditions to be studied were investigated for a 30-day experimental period. Phosphate release under non-sterile conditions exceeded the release observed under sterile conditions in all systems regardless of whether they were anaerobic, aerobic, mixed or static. In addition, mixing enhanced phosphorus release under all the conditions investigated.Release of phosphate was observed under both anaerobic and aerobic conditions. Anaerobic release was greater than aerobic release in all cases except for two. The average release obtained in the aerobic mixed non-sterile systems was greater than the average release observed in the anaerobic static sterile systems and was equal to the average release observed in the anaerobic static non-sterile systems. This higher release under aerobic conditions could probably be attributed to mixing.     

Electricity generation from cysteine in a microbial fuel cell

In a microbial fuel cell (MFC), power can be generated from the oxidation of organic matter by bacteria at the anode, with reduction of oxygen at the cathode. Proton exchange membranes used in MFCs are permeable to oxygen, resulting in the diffusion of oxygen into the anode chamber. This could either lower power generation by obligate anaerobes or result in the loss in electron donor from aerobic respiration by facultative or other aerobic bacteria. In order to maintain anaerobic conditions in conventional anaerobic laboratory cultures, chemical oxygen scavengers such as cysteine are commonly used. It is shown here that cysteine can serve as a substrate for electricity generation by bacteria in a MFC. A two-chamber MFC containing a proton exchange membrane was inoculated with an anaerobic marine sediment. Over a period of a few weeks, electricity generation gradually increased to a maximum power density of 19 mW/m(2) (700 or 1000 Omega resistor; 385 mg/L of cysteine). Power output increased to 39 mW/m(2) when cysteine concentrations were increased up to 770 mg/L (493 Omega resistor). The use of a more active cathode with Pt- or Pt-Ru, increased the maximum power from 19 to 33 mW/m(2) demonstrating that cathode efficiency limited power generation. Power was always immediately generated upon addition of fresh medium, but initial power levels consistently increased by ca. 30% during the first 24 h. Electron recovery as electricity was 14% based on complete cysteine oxidation, with an additional 14% (28% total) potentially lost to oxygen diffusion through the proton exchange membrane. 16S rRNA-based analysis of the biofilm on the anode of the MFC indicated that the predominant organisms were Shewanella spp. closely related to Shewanella affinis (37% of 16S rRNA gene sequences recovered in clone libraries).     

以葡萄糖为底物的微生物燃料电池产电特性研究

以城市污水处理厂的好氧和厌氧污泥作为接种液,通过构建双室微生物燃料电池,考察了以葡萄糖为底物时连续流微生物燃料电池降解有机物及产电的特性.结果表明:以泡沫镍板、石墨板作为阳极时的产电效果较好;在一定温度范围内,提高温度可增大电池的输出电压和开路电压;对阴极室供氧可提高微生物燃料电池的开路电压和输出电压;随着外接电阻值的增大,微生物燃料电池的输出电流变小,符合原电池电极的一般规律.     

Operation of a horizontal subsurface flow constructed wetland – Microbial fuel cell treating wastewater under different organic loading rates

The aim of the present work is to determine whether a horizontal subsurface flow constructed wetland treating wastewater could act simultaneously as a microbial fuel cell (MFC). Specifically, and as the main variable under study, different organic loading rates were used, and the response of the system was monitored. The installation consisted of a synthetic domestic wastewater-feeding system and a pilot-scale constructed wetland for wastewater treatment, which also included coupled devices necessary to function as an MFC. The wetland worked under continuous operation for 180 d, treating three types of synthetic wastewater with increasing organic loading rates: 13.9 g COD m⁻² d⁻¹, 31.1 g COD m⁻² d⁻¹, and 61.1 g COD m⁻² d⁻¹. The COD removal efficiencies and the cell voltage generation were continuously monitored. The wetland worked simultaneously as an MFC generating electric power. Under low organic loading rates, the wastewater organic matter was completely oxidised in the lower anaerobic compartment, and there were slight aerobic conditions in the upper cathodic compartment, thus causing an electrical current. Under high organic loading rates, the organic matter could not be completely oxidised in the anodic compartment and flowed to the cathodic one, which entered into anaerobic conditions and caused the MFC to stop working. The system developed in this work offered similar cell voltage, power density, and current density values compared with the ones obtained in previous studies using photosynthetic MFCs, sediment-type MFCs, and plant-type MFCs. The light/darkness changes caused voltage fluctuations due to the photosynthetic activity of the macrophytes used (Phragmites australis), which affected the conditions in the cathodic compartment.     

Further treatment of decolorization liquid of azo dye coupled with increased power production using microbial fuel cell equipped with an aerobic biocathode

A microbial fuel cell (MFC) incorporating a recently developed aerobic biocathode is designed and demonstrated. The aerobic biocathode MFC is able to further treat the liquid containing decolorization products of active brilliant red X-3B (ABRX3), a respective azo dye, and also provides increased power production. Batch test results showed that 24.8% of COD was removed from the decolorization liquid of ABRX3 (DL) by the biocathode within 12 h. Metabolism-dependent biodegradation of aniline-like compound might be mainly responsible for the decrease of overall COD. Glucose is not necessary in this process and contributes little to the COD removal of the DL. The similar COD removal rate observed under closed circuit condition (500 Ω) and opened circuit condition indicated that the current had an insignificant effect on the degradation of the DL. Addition of the DL to the biocathode resulted in an almost 150% increase in open cycle potential (OCP) of the cathode accompanied by a 73% increase in stable voltage output from 0.33 V to 0.57 V and a 300% increase in maximum power density from 50.74 mW/m² to 213.93 mW/m². Cyclic voltammetry indicated that the decolorization products of the ABRX3 contained in the DL play a role as redox mediator for facilitating electron transfer from the cathode to the oxygen. This study demonstrated for the first time that MFC equipped with an aerobic biocathode can be successfully applied to further treatment of effluent from an anaerobic system used to decolorize azo dye, providing both cost savings and high power output.     

Biosorption of 2,4-dichlorophenol by live and chemically inactivated anaerobic granules

Equilibrium sorption isotherms and sorption kinetics of 2,4-dichlorophenol (2,4-DCP) on live and chemically inactivated anaerobic granules were investigated using batch serum bottle tests. A general metabolic inhibitor, sodium azide, was used to inactivate the biological activity of the anaerobic biomass. Experimental results showed that the difference in the biosorption of live and chemically inactivated anaerobic granules were not significant, suggesting that anaerobic biosorption is mainly a physical-chemical process and that metabolically mediated diffusion in the process is negligible.     

Bacterial populations and their roles in a pharmaceutical-waste anaerobic filter

The bacterial populations, their roles and distribution in an anaerobic filter treating a simulated pharmaceutical effluent containing a branched-chain fatty acid (BCFA) were studied. The BCFA degradation pathway and mechanisms were also investigated. The biofilm from the filter was enriched in serum bottle cultures using different BCFAs and fatty acids as the sole carbon source. The anaerobic biofilm was a consortium of (1) BCFA-degrading Syntrophomonas spp. which produced ethanoic acid and H₂, (2) H₂-utilizing Methanococcus spp. and (3) ethanoate-utilizing Methanothrix spp. Beta-oxidation was proposed as the acidogenic mechanism. The bacterial consortium could degrade BCFAs with tertiary carbon but not those with quaternary carbon. Branching at the alpha or beta position along the carbon chain interfered with the beta-oxidation mechanisms. Bacterial distribution in the filter was uneven, which was attributed to incomplete mixing.     

The effect of thermal pretreatment on the anaerobic biodegradability and toxicity of waste activated sludge

The management of sludges generated by biological treatment of wastewaters has become an increasingly severe problem in recent years. The objective of this study was to examine the effect of thermochemical pretreatment on the anaerobic biodegradability and toxicity of waste activated sludge (WAS). In order to accomplish this, the degradability and toxicity of pure nitrogenous organic compounds present in WAS, and mixtures of these compounds, were also evaluated.The anaerobic bioconvertibility and toxicity of the various organics were determined using batch bioassay techniques. It was found that WAS bioconvertibility increased with increasing pretreatment temperature up to a maximum at 175°, and this resulted in an increase in methane production of 27% over the control. With the compounds and cultures used, mesophilic bioconvertibility and toxicity were found to be significantly higher than the corresponding values under thermophilic conditions. Finally, it was found that most of the pure individual nitrogen compounds and simple mixtures tested were quite biodegradable, although at the concentrations evaluated (20 gl⁻¹) most were toxic. It was also noted that small changes in structure could have a significant effect on both toxicity and bioconvertibility. In most cases thermochemical pretreatment of these individual compounds resulted in decreased bioconvertibility and increased toxicity.In conclusion it can be stated that thermochemical pretreatment enhances WAS bioconvertibility, while under identical treatment conditions, resulted in a considerable reduction in the bioconvertibility of individual nitrogen compounds and mixtures. This effect appears to be due to the conversion of biodegradable organics to refractory ones. Further, the toxicity of WAS after thermochemical pretreatment appears to be due to its solubilization, and conversion of these soluble products to toxic compounds under more extreme treatment conditions.     

An anaerobic two-layer permeable reactive biobarrier for the remediation of nitrate-contaminated groundwater

In this paper, an anaerobic two-layer permeable reactive biobarrier system consisting of an oxygen-capturing layer followed by a biodegradation layer was designed firstly for evaluating the remediation effectiveness of nitrate-contaminated groundwater. The first layer filling with granular oxygen-capturing materials is used to capture dissolved oxygen (DO) in groundwater in order to create an anaerobic condition for the microbial denitrification. Furthermore, it can also provide nutrition, such as carbon and phosphorus, for the normal metabolism of immobilized denitrifying bacteria filled in the second layer. The second layer using granular activated carbon as microbial carrier is able to biodegrade nitrate entering the barrier system. Batch experiments were conducted to identify the effect of DO on microbial denitrification, oxygen-capturing performance of zero valent iron (ZVI) powder and the characteristics of the prepared oxygen-capturing materials used to stimulate growth of denitrifying bacteria. A laboratory-scale experiment using two continuous upflow stainless-steel columns was then performed to evaluate the feasibility of this designed system. The first column was filled with granular oxygen-capturing materials prepared by ZVI powder, sodium citrate as well as other inorganic salts, etc. The second column was filled with activated carbon immobilizing denitrifying microbial consortium. Simulated nitrate-contaminated groundwater (40 mg NO₃–N/L, pH 7.0) with 6 mg/L of DO content was pumped into this system at a flow rate of 235 mL/d. Samples from the second column were analyzed for nitrate and its major degradation byproduct. Results showed that nitrate could be removed more than 94%, and its metabolic intermediate, nitrite, could also be biodegraded further in this passive system. Further study is necessary in order to evaluate performance of its field application.