微生物光电化学池去除硝酸盐氮:以PANI/TiO2-NTs为光阳极

利用微生物光电化学池(MPEC)去除污染物是一种经济高效环保的方法.本实验在制备获得聚苯胺/二氧化钛纳米管阵列(PANI/TiO_2-NTs)复合光电极的基础上,构建了由PANI/TiO_2-NTs光阳极和生物阴极组成的MPEC系统,并对其去除硝酸盐氮(NO~-_3-N)的性能进行研究.结果表明,PANI负载时间为80 s时,PANI/TiO_2-NTs电极光电性能最佳,相比于TiO_2-NTs电极光电流密度增大约一倍,PANI的修饰有效提高了光能利用率.构建的MPEC系统能在无外加电压的条件下利用光能驱动实现自养反硝化脱氮,NO~-_3-N的生物降解符合准一级反应动力学方程.光响应电流密度越大,系统反硝化脱氮性能越好,NO~-_3-N初始浓度为25 mg·L~(-1)时,当光响应电流密度从0.17 mA·cm~(-2)增加至0.67 mA·cm~(-2),平均反硝化速率从0.83 mg·(L·h)~(-1)增大到2.83 mg·(L·h)~(-1).对生物阴极微生物膜进行了高通量测序,发现Pseudomonas所占比例最大(27.37%)为优势菌属.分析认为PANI/TiO_2-NTs光阳极产生的光生电子通过外电路传递到阴极,Pseudomonas、Alishewanella和Flavobacterium等具有自养反硝化能力和电化学活性的微生物可直接利用电极上的电子作为唯一的电子供体进行自养反硝化脱氮.     

喹啉和吡啶共存条件下的MFC产电特性研究

喹啉和吡啶往往共存于实际废水中,本文通过构双极室MFC,以铁氰化钾为电子受体,对喹啉和吡啶在MFC中的降解以及产电性进行研究.结果表明,MFC的最大输出电压随着葡萄糖浓度的降低而降低,当喹啉和吡啶初始浓度均为500mg·L-1,葡萄糖浓度分别为1000、500、100mg·L-1时,最高输出电压逐渐降低,分别为606、537、354mV;最大体积功率密度为18.4、14.4和6.3W.m-3.当以等浓度500mg·L-1的喹啉和吡啶作混合燃料时,MFC的内阻超过1250Ω,最大体积功率密度为2.9W.m-3.周期结束时,COD的去除率达79%以上,喹啉和吡啶均可以完全去除,喹啉的降解速率明显高于吡啶.MFC可以利用喹啉和吡啶作为混合燃料,这为含喹啉和吡啶共存类实际废水的MFC处理提供了理论依据.     

微生物燃料电池中产电微生物电子传递研究进展

微生物燃料电池集产电和污水净化为一体,作为一种新型的能源回收技术得到人们的广泛关注。从微生物燃料电池工作原理来看,电子能否顺利地传递到阳极表面对于电流的产生起着关键作用。因此,本文重点阐述了电子在产电微生物体内产生的途径、电子从微生物体内向阳极传递的不同方式以及阳极材料对产电微生物附着和电子传递的影响。从生物化学、电化学和材料学上对产电微生物体内的电子到阳极整个过程进行全面的综述。明确电子传递的关键环节,为新型高效阳极材料的开发提供思路。     

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities: A laboratory study

A laboratory study was conducted to investigate volatile organic compound(VOC) emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition(5924 ng C/(kg·hr)) was significantly higher than that under the flooded condition(2211 ng C/(kg·hr)). One "peak emission window" appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis(DGGE) showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.     

再生水中的Pb对萝卜根际土壤微生物群落结构的影响研究

采用盆栽方法研究再生水、再生水+Pb、清水+Pb处理浇灌萝卜,以清水浇灌为对照对萝卜根际土壤微生物群落的影响进行研究。结果表明:(1)土壤总PLFA含量及各菌群生物量从大到小依次为:再生水再生水+Pb清水清水+Pb。再生水灌溉有利于萝卜根际微生物各类群数量的增加,丰富微生物多样性。用含铅的溶液(再生水+Pb、清水+Pb)浇灌萝卜,可抑制土壤微生物各类群的数量,G-受到的抑制尤为明显。(2)主成分分析表明,再生水灌溉与对照相比,土壤微生物群落结构差异最大。(3)土壤微生物各类群与土壤速效钾、硝酸盐氮含量呈极显著正相关(P0.01),真菌、放线菌与土壤有机质含量,G~+、G~-菌与p H均呈极显著正相关(P0.01)。G~+、G~-与萝卜地下鲜重均呈极显著负相关(P0.01),土壤微生物各类群与地上部分硝酸盐含量、与根冠比呈极显著正相关(P0.01)。     

Microbial bioavailability of dissolved organic nitrogen (DON) in the sediments of Lake Shankou, Northeastern China

Dissolved organic nitrogen(DON)extracted from Lake Shankou sediments using KCl was isolated into hydrophobic and hydrophilic fractions.The bioavailabilities of the hydrophobic and hydrophilic fractions to three types of bacterial communities collected from sediments,activated sludge and compost products were examined.The DON recoveries obtained by DAX-8 and cation exchange resins treatment were 96.17% ± 1.58% and 98.14% ±0% for the samples obtained from N4 and N14 stations,respectively.After 25 days of incubation at 25°C,most DON(59% to 96%)was degraded.Hydrophilic DON exhibited a higher reduction rate than hydrophobic DON during the growth phase.Untreated wastewater from Changshuihe town was the main degradable DON source to station N4,and 93% of hydrophilic DON and 80% of hydrophobic DON were degraded.Station N14 received a large amount of refractory DON from forest soils and exhibited DON degradation rates of 82% and 71% for the hydrophilic and hydrophobic fractions,respectively.Amino acid contents and fluorescence intensities were also analyzed.Approximately 27% to 74% of amino acids were taken up by day 5,and their concentration gradually increased in the following days due to the decomposition of dissolved proteins.Parallel factor analysis resulted in identification of tryptophan-like proteins,tyrosine-like proteins and FA-like substances.During the growth phase,40%–51% of the tryptophan-like proteins were taken up by bacteria,and the accumulation of tyrosine-like proteins was attributed to the release of biotic substances.The concentration of the FA-like substances decreased due to microbial decomposition.     

The biological effect of metal ions on the granulation of aerobic granular activated sludge

As a special biofilm structure, microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge (AGAS). This experiment was to investigate the biological effect of Ca^2 +, Mg^2 +, Cu^2 +, Fe^2 +, Zn^2 +, and K⁺ which are the most common ions present in biological wastewater treatment systems, on the microbial attachment of AGAS and flocculent activated sludge (FAS), from which AGAS is always derived, in order to provide a new strategy for the rapid cultivation and stability control of AGAS. The result showed that attachment biomass of AGAS was about 300% higher than that of FAS without the addition of metal ions. Different metal ions had different effects on the process of microbial attachment. FAS and AGAS reacted differently to the metal ions as well, and in fact, AGAS was more sensitive to the metal ions. Specifically, Ca^2 +, Mg^2 +, and K⁺ could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations, Cu^2 +, Fe^2 +, and Zn^2 + were also beneficial to the microbial attachment of FAS at low concentrations, but Cu^2 +, Fe^2 +, and Zn^2 + greatly inhibited the attachment process of AGAS even at extremely low concentrations. In addition, the acylated homoserine lactone (AHL)-based quorum sensing system, the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions. As all these parameters had close relationships with the microbial attachment process, the microbial attachment may be affected by changes of these parameters.     

The role of lipids in fermentative propionate production from the co-fermentation of lipid and food waste

● Lipid can promote PA production on a target from food waste. ● PA productivity reached 6.23 g/(L∙d) from co-fermentation of lipid and food waste. ● Lipid promoted the hydrolysis and utilization of protein in food waste. ● Prevotella , Veillonella and norank _f _Propioni bacteriaceae were enriched. ● Main pathway of PA production was the succinate pathway. Food waste (FW) is a promising renewable low-cost biomass substrate for enhancing the economic feasibility of fermentative propionate production. Although lipids, a common component of food waste, can be used as a carbon source to enhance the production of volatile fatty acids (VFAs) during co-fermentation, few studies have evaluated the potential for directional propionate production from the co-fermentation of lipids and FW. In this study, co-fermentation experiments were conducted using different combinations of lipids and FW for VFA production. The contributions of lipids and FW to propionate production, hydrolysis of substrates, and microbial composition during co-fermentation were evaluated. The results revealed that lipids shifted the fermentation type of FW from butyric to propionic acid fermentation. Based on the estimated propionate production kinetic parameters, the maximum propionate productivity increased significantly with an increase in lipid content, reaching 6.23 g propionate/(L∙d) at a lipid content of 50%. Propionate-producing bacteria Prevotella, Veillonella, and norank_f_Propionibacteriaceae were enriched in the presence of lipids, and the succinate pathway was identified as a prominent fermentation route for propionate production. Moreover, the Kyoto Encyclopedia of Genes and Genomes functional annotation revealed that the expression of functional genes associated with amino acid metabolism was enhanced by the presence of lipids. Collectively, these findings will contribute to gaining a better understanding of targeted propionate production from FW.     

矿井通风网络数据可靠性检验

进行矿井通风阻力测定时,由于受环境的温度、湿度、压力传递存在时间差以及测点处标高不准确等因素的影响,根据实测数据,计算所得矿井巷道基础数据存在一定的误差,常用的测量数据检验方法只能对若干条通路进行闭合回路检验,而不能对全矿井通风网络基础参数进行可靠性检验。本文中所介绍的检验方法将风网基础数据输入通风网络解算软件,以实测风量和经过计算所得巷道风阻为基准,实测风量为目标条件,进行计算机通风网络模拟,对全矿井巷道风阻进行连续的优化调整,使通风网络模拟结果与实际测定各巷道风量基本符合,从而实现全矿井风网基础数据的可靠性检验。该方法在某矿进行了实际应用,实践证明此方法科学、准确的获得了全矿巷道风阻参数,为矿井的通风改造奠定了技术基础。     

Recent advances in three typical configurations and applications of bioelectrochemical systems北大核心CSCD

As the world's freshwater resources and available energy are alarmingly decreasing, the bioelectrochemical system (BES) is a cutting-edge technology for the resolution of the resource and energy issue. Researchers have paid much attention to t he application of t he BES configuration. Based on t he brief i ntroduction of m icrobial f uel cell a nd m icrobial electrolytic cell structure, principles, and domestic and foreign research, the BES and its influencing factors are introduced, specifically including: microbial activity, electrode materials, and configuration. Three important aspects (i.e., the electrode chamber, the reaction chamber, and micro-sensor) are summarized, and the advantages and disadvantages of single-electrode and multi-electrode chambers are compared, based on the microbial desalination cell. Microbial electrolysis desalination cell: Microbial electrolysis desalination and chemical-production cell have been discussed to introduce increasing reaction chamber configuration; this review focuses on the research of BES monitoring with regards to biochemical oxygen demand. The potential applications of the research progress are explored. The results show that the configuration of multi-chamber microbial fuel cell is complex and its efficiency is low, while the single chamber configuration is advantageous. The reaction chamber added is mainly aimed at desalination, and the study of the desalination pool still needs to be focused on optimizing the cation exchange membrane to maintain the anode pH balance and reduce the air cathode dissolved oxygen. Microbial electrode sensor can be applied in more areas, and its sensitivity and long-term stability need to be further improved. However, there is relatively less research on the abundance and activity of electricigen communities; the configurations and scopes of application of BES are still the research priority. © 2018 Science Press. All rights reserved.