剩余污泥为燃料的微生物燃料电池产电特性研究

利用厌氧污泥作为接种体在不加入任何营养元素的条件下,经过20　d成功地启动了单室无膜微生物燃料电池.启动成功后对剩余污泥作为燃料产电特性以及底物的变化进行了研究.结果表明,微生物燃料电池产生的最大电压为495　mV(外电阻为1 000　Ω),最大功率密度达到44 mW·m^-2,稳定期间内阻约为300　Ω.在1个运行周期中,污泥SS和VSS的去除率分别为27.3%和28.7%,pH值的变化范围为6.5～8.0, COD的起始浓度为617 mg·L^-1,浓度随时间的增加而增大并稳定在1 150 mg·L^-1左右,随后逐渐下降,糖的起始浓度为47 mg·L^-1,逐渐增大到60 mg·L^-1之后浓度逐渐下降.微生物燃料电池可以将剩余污泥中的化学能转化为最清洁的电能,为污泥资源化提供了新的思路.     

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180–320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health e ects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coe cients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641–1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%–50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.     

改良MTT法在鱼类细胞毒性实验中的使用条件

文章利用斑点叉尾鮰鱼卵巢细胞(CCO)、鲤鱼上皮癌细胞(EPC)、草鱼肾细胞(CIK)探讨改良四噻唑蓝(MTT)比色法在测定污染物对鱼类细胞急性毒性实验中的最佳条件。通过实验发现其最佳实验条件为570nm波长下,MTT作用4h,MTT终浓度1mg/mL,最佳接种量的确定因每种细胞的特性而不同,生长速度快的细胞接种量较少。     

电催化-生物电化学耦合系统处理青霉素废水的机制

抗生素生产过程中产生大量含有残存抗生素的生产废水,传统的污水生物处理技术难以有效地处理此类高浓度抗生素废水.针对此问题,采用电催化-生物电化学耦合系统来处理含有典型的β-内酰胺类抗生素青霉素的废水,利用硼掺杂金刚石（boron-doped diamond,BDD）电催化电极对青霉素废水进行预处理,其出水进入生物电化学系统（bioelectrochemical system,BES）进行后处理.研究发现,经电催化系统预处理后青霉素的去除率为89%,出水进入BES后可以稳定运行,该出水中又有79%的青霉素被BES去除,获得最大功率密度为（1124±28）mW·m^-2,与直接进青霉素原始废水的BES反应器相比提高了473%.经过电催化-生物电化学两级耦合系统处理后青霉素的总去除率达到98%.对BES反应器阳极生物量和生物相分析结果表明,青霉素对阳极混合菌群生物量和变形菌门微生物（主要产电菌）有一定的抑制作用,且会降低形成阳极生物膜的主要微生物不动杆菌属Acinetobacter和具有产电功能芽孢杆菌属Bacillus在反应器中含量,这是影响反应器产电性能和处理效果的主要原因.青霉素废水经电催化降解后,浓度明显降低,有效缓解了青霉素对BES的抑制作用,提高废水的可生化性,因此电催化-生物电化学耦合系统是一种高效低能耗处理抗生素废水的新工艺.     

孕期低剂量镉暴露对不同性别胎鼠肝脏发育的影响及其分子调控机制的研究

为探究镉对胎儿肝脏发育的毒性作用.拟选用15只性成熟的8周龄的雌性C57BL/6小鼠,与雄鼠交配见栓后,于妊娠第7.5 d(Embryonic 7.5,E7.5)时,随机分为3组(每组5只),分别通过饮用水暴露法饲喂0、20和40 mg·L^-1的氯化镉溶液,并于E14.5 d时收集各组小鼠的胎儿肝脏等组织.通过Ki67和TUNEL染色方法探究镉对不同性别胎鼠肝脏的增殖功能和凋亡功能的影响,并通过PCR芯片筛查和实时定量PCR方法检测镉处理组的雌性和雄性胎鼠肝脏中与细胞增殖和凋亡功能相关基因的表达变化.此外,我们还将通过石墨炉火焰原子吸收技术对镉处理组的雌性和雄性胎鼠的镉含量进行检测.结果显示:孕期低剂量镉暴露对胎儿体重、胎肝重量和肝脏指数均无显著性影响.在本实验条件下,镉对胎鼠肝脏的凋亡功能无显著性影响,但对增殖功能具有抑制作用,且该抑制作用具有雌性依赖性的特征.镉特异性诱导雌性胎鼠肝脏中NF1等多个细胞增殖功能相关基因以及TGF-β1信号通路分子的表达失衡;但对雄性胎鼠肝脏中相关基因的表达水平无显著性影响.镉在雌性胎儿组织中的积累量显著高于雄性胎儿组织.综上所述,孕期低剂量镉暴露特异性抑制雌性胎儿肝脏的细胞增殖功能,并诱导雌性胎儿肝脏中NF1等多个增殖功能相关基因以及TGF-β1信号通路分子的表达失衡,该性别依赖性的抑制作用可能与镉在雌性胎儿中相对较高的积累量相关.     

生物电化学系统对河道沉积物中抗生素的强化去除

生物电化学系统已被证明可以有效降解废水或污泥中的抗生素,但对于河道沉积物中抗生素降解效果的研究还十分有限.本研究以河道沉积物为底物,考察了沉积物中本底抗生素在微生物电解池（microbial electrolysis cell, MEC）和微生物燃料电池（microbial fuel cell, MFC）中的去除、迁移和降解效率,以及反应器运行期间的电化学性能和微生物种群结构变化.结果显示,MEC和MFC均可以强化沉积物中抗生素的去除,喹诺酮类抗生素和四环素类抗生素中的CTC的去除是向上覆水中迁移与生物电化学降解共同作用的结果,而大环内酯类抗生素和四环素类抗生素中的TC和OTC的去除主要是依靠生物电化学降解作用.TC和OTC在MEC中的降解效率分别比MFC高出82.6%和29.5%,而MFC对大环内酯类抗生素的降解效率比MEC高27.6%~40.6%.电化学性能测试结果显示,以河道沉积物为底物的MFC内阻较大导致其功率密度相对较低,但MFC阳极比MEC阳极表现出了更好的氧化效果.微生物种群结构变化分析发现,门水平上的Proteobacteria及其对应的纲水平上的Deltaproteobacteria和Gammaproteobacteria可能对抗生素的强化去除起到了主要的积极作用,而且MFC阳极比MEC更容易富集Proteobacteria.     

苯胺对小鼠成纤维细胞L929的体外毒性评价

探讨不同浓度的苯胺化合物对小鼠成纤维细胞L929的体外毒性作用,为满足危险化学品分类鉴定和风险评估需求、更好地预防环境化合物对人体健康的损害提供理论依据。体外培养L929细胞,分别将不同浓度的苯胺化合物(0、0.001、0.01、0.1、1、10μg·mL~(-1))加入培养基中处理细胞,在不同时间点分别取材,MTT检测细胞增殖率,AO/PI染色检测细胞存活率,Annexin V-PI染色后流式细胞仪检测细胞凋亡,相关检测试剂盒测定细胞内活性氧(ROS)的含量及总谷胱甘肽的含量。结果表明,高浓度(1、10μg·mL~(-1))的苯胺化合物对L929细胞的生长和增殖具有显著的抑制效应。即使浓度降低至0.1μg·mL~(-1),在处理48 h后,细胞的存活数量显著下降,说明其对细胞增殖具有浓度和时间的累积效应和依赖性。同时,对各组细胞采用流式细胞仪测定细胞凋亡,发现低浓度的苯胺对细胞凋亡影响并不明显,但高浓度的苯胺处理后,细胞凋亡和坏死数量显著增加。ROS含量和GSH含量检测结果显示,较低浓度的苯胺对细胞氧化应激反应并无显著影响,但浓度至0.1μg·mL~(-1)时,细胞较对照组出现明显的氧化应激反应,说明细胞已受损,再继续培养将会导致细胞死亡。上述研究结果提示,高浓度苯胺化合物可显著影响L929细胞存活率,且具有时间和浓度累积效应。其毒性机制可能与细胞内活性氧增加、谷胱甘肽耗竭有关。     

Microbial fuel cell with three-dimensional electrodes for domestic wastewater treatment and electricity generation北大核心CSCD

A single chamber microbial fuel cell (MFC) with three-dimensional electrodes packed bed carbon felts was developed to treat domestic wastewater while simultaneously generating electricity. The influence of batch and continuous operation mode on treatment effectiveness and electricity production of the MFC was investigated to provide a reference for the application of the MFC. The MFC with a total working volume of 1 440 mL was operated in the fed-batch mode for 5 d repeatedly three times, and then shifted to the continuous mode. During the testing of the continuous mode, wastewater was continuously pumped into the anode compartment at a flow rate of approximately 0.2 mL/min, resulting in a hydraulic retention time of 5 d. During the batch test, the MFC obtained 91.1% chemical oxygen demand (COD) and 98.2% NH4 +-N removal, which accorded with the first criteria specified in the discharge standard of pollutants for municipal wastewater treatment plants in China (GB18918-2002). A maximum power density of 27.88 mW/m3 was achieved at a 51 Ω external resistor. During the continuous test, the COD removal efficiencies ranged from 83.2% to 97.4%. The concentration of NH4 +-N gradually decreased within 5 d and was then maintained below 9.45 mg/L, thus an enhanced removal performance of NH4 +-N was acquired. However, a low removal efficiency of total nitrogen was observed owing to the accumulation of NO3 --N in the effluent since day 11. Additionally, the MFC continually generated electricity with a maximum power density of 582.5 mW/m3 and average output voltage of 0.087 7 V during the stable period in the continuous operation mode. Moreover, 16S rRNA gene high-throughput sequencing showed that Thauera sp., Saprospiraceae-UN sp., and OPB56-UN sp. were identified as dominant populations. The results suggested that the organic matter associated with power generation was constantly utilized by the microorganisms in the reactor, which caused an excellent electricity generation performance during the continuous test. Therefore, the continuous operation mode could improve the low output voltage phenomenon in the MFC. Thauera sp., as a type of nitrate-reducing bacteria, was enriched in the autotrophic denitrifying microbial communities; therefore, bio-enrichment with denitrifying bacteria such as Thauera sp. could decrease the concentration of NO3 --N in the effluent during the continuous operation mode, which is expected to be an innovation for improvement of wastewater treatment. © 2018 Science Press. All rights reserved.     

Cd~(2+)对BY-2细胞的毒性机制及水杨酸的缓解作用

镉对生态环境的危害表现出对植物这种定生生物的毒害性。以绿色荧光蛋白(GFP)膜泡标记的烟草BY-2细胞为实验材料,分别在荧光显微镜和激光共聚焦显微镜下观察了Cd2+对植物细胞的毒害作用和机制,并研究了水杨酸(SA)处理对Cd2+植物细胞毒害的缓解作用。研究发现激光共聚焦显微镜可以观察到Cd2+处理3 h后细胞荧光亮度减弱,6 h时细胞皱缩和液泡缩小,9 h细胞大多死亡。在Cd2+胁迫同时加入SA,可显著提高细胞成活时间,荧光亮度增强、液泡化程度加大,同时能够观察到荧光标记的细胞膜包裹Cd2+的高荧光颗粒。SA处理的细胞还通过高度液泡化来缓解重金属Cd2+的毒性。结果表明具有生物活性的SA诱导细胞的液泡化,并通过膜成分对重金属的包裹和结合进一步降低了重金属对植物细胞的毒害。因此水杨酸缓解重金属对植物细胞的毒性,是通过诱导细胞的液泡化和膜对重金属离子的包裹束缚而实现的。     

A mini-microbial fuel cell for voltage testing of exoelectrogenic bacteria

Current methods for testing the electricity generation capacity of isolates are time- and labor-consuming. This paper presents a rapid voltage testing system of exoelectrogenic bacteria called Quickscreen, which is based on a microliter microbial fuel cell (MFC). Geobacter sulfurreducens and Shewanella baltica were used as the model exoelectrogenic bacteria; Escherichia coli that cannot generate electricity was used as a negative control. It was found that the electricity generation capacity of the isolates could be determined within about five hours by using Quickscreen, and that its time was relatively rapid compared with the time needed by using larger MFCs. A parallel, stable, and low background voltage was achieved using titanium as a current collector in the blank run. The external resistance had little impact on the blank run during the initial period. The cathode with a five-hole configuration, used to hydrate the carbon cathode, gave higher cathode potential than that with a one-hole configuration. Steady discharge and current interrupt methods showed that the anode mostly contributed to the large internal resistance of the Quickscreen system. However, the addition of graphite felt decreased the resistance from 18 to 5 kΩ. This device was proved to be useful to rapidly evaluate the electricity generation capacity of different bacteria.