课程文献中心 更多>>

关键词： 膜生物反应器   絮凝剂   除磷   膜污染  

摘要： 采用一体浸没式膜生物反应器(MBR)处理模拟生活污水,考察了在投加不同铁盐絮凝剂(FeSO4和PFS)条件下反应器的运行效率及膜污染特性。进出水水质分析结果表明:铁盐絮凝剂的投加可明显提高MBR的除磷效率,反应器总磷的平均去除率由20.23%分别提高至74.29%和81.09%,对COD和氨氮的去除率没有明显的影响;污泥沉降得到改善,SVI明显降低,使泥饼层更加疏松,易于清洗。同时通过对不同絮凝剂条件下污泥混合液胞外聚合物以及膜上污染物的三维荧光分析,发现絮凝剂的加入能明显减少胞外聚合物中的多糖浓度以及膜上污染物质的结构类型,且主要减少了胡敏酸类物质对膜的污染。这对于提高出水水质,减缓膜污染具有重要意义。以上结果可为FeSO4和PFS在MBR中的应用提供参考。

关键词： 杜鹃花   扦插   基质   ABT溶液  

摘要： 研究不同基质和ABT浓度处理对4个拟作为西安地区推广的杜鹃花品种扦插成活率的影响。采用5种不同的基质配比和5种不同的ABT处理对4个品种的杜鹃花进行了扦插试验。结果表明,泥炭与珍珠岩的混合基质或蛭石基质最适合该4个品种的扦插生根,生根粉对4个杜鹃花品种的成活率影响不大。4个品种在最佳扦插条件下的成活率在80%~93%之间。研究结果为这些品种的快速批量生产提供了技术支持。

关键词： Woodchip bioreactors   Activated carbon   Flaxseed cake   Biochar   Tile drainage  

摘要： Excess nutrient inflow from tile-drained agricultural fields significantly contributes to the pollution of surface waters in Lithuania. Therefore, two parallel experiments, each using three pilot-scale woodchip-denitrifying bioreactors, were conducted for 2.5- and 1.5-year periods to test whether activated carbon (C) and flaxseed cake (both 10% v/v) and biochar (10% v/v and 20% v/v made of deciduous wood) additives, respectively, can enhance the removal of nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) from tile drainage water and reduce C losses from bioreactors. Higher NO3-N removal efficiencies and rates were achieved in bioreactors amended with activated C (10% v/v) and biochar (20% v/v) than in those amended with woodchips alone. Bioreactors amended with 10% v/v flaxseed cake and 10% v/v biochar showed no significant differences from those amended with woodchips alone. The ability to enhance NO3-N removal by the addition of activated C and biochar was particularly evident at lower temperatures (<= 10.0 degrees C). Moreover, activated C has proven to be an effective additive capable of substantially reducing C losses and supporting the lowest C/N (i.e., carbon loss to N removal) ratios. To a lesser extent, these capabilities were also characteristic of biochar-amended woodchips, whereas the addition of flaxseed cake resulted in the highest C/N removal ratios. These experiments also revealed that woodchips, alone or amended with flaxseed cake or activated C, are a suitable media that can allow PO4-P removal. However, the addition of biochar demonstrated large releases of PO4-P and other inorganic elements. Biochar itself was found to be a potential PO4-P source that poses a risk of large startup and over time releases. Although the addition of activated C under non-N-limiting conditions resulted in undesirable sulfate-sulfur (SO4-S) reduction (this occurred in all study bioreactors), the experiments demonstrated that the addition of activated C can be

关键词： 传质   生物反应器   气液两相流   曝气搅拌桨   微气泡   微孔膜  

摘要： 微气泡具有气液接触面积大、气体溶解速率快、上升速度慢和水中停留时间长等理化特征,非常适合于高气液传质效率需求的生物发酵过程。本文介绍了能够耦合生物反应器的几种微气泡发生装置,分别为微气泡分散器、微孔膜、流体振荡器耦合微孔膜和微气泡曝气搅拌桨;并简述了微气泡发生装置耦合搅拌式生物反应器、气升式生物反应器和生物膜反应器在生物反应过程的应用进展;最后回顾了二氧化碳微气泡在生物反应器的应用研究进展。指出微气泡耦合生物反应器的研究仍处于起步阶段,在放大规律和能耗方面仍处于研究空白。微气泡耦合生物反应器的发展对工业生物技术、石油化工、污水处理和资源再利用等的发展具有重要的意义。

关键词： 赤霉素(GA3)   蓝莓   果实品质  

摘要： 以南高丛蓝莓‘安娜’为试材,用浓度为0、15、30、60 mg·L^-1的赤霉素(GA3)溶液喷施植株的果实,待果实成熟后测定果实品质的各项指标,研究GA3对蓝莓果实品质的影响,探讨GA3在蓝莓上应用的最佳浓度。结果表明:不同浓度GA3处理下,蓝莓果实品质的变化显著,与对照相比,果实的单果质量、横径、纵径、硬度、可溶性固形物含量、多酚含量、花色苷含量、过氧化物酶(POD)活性、内源GA3含量均有所增加,总酸含量和超氧化物歧化酶(SOD)活性下降。综合分析各指标,30 mg·L^-1GA3浓度处理下,果实的果质量、硬度、多酚、花色苷和内源GA3含量最大,GA3处理效果依次为30 mg·L^-1>15 mg·L^-1>60 mg·L^-1。

关键词： 黄嘌呤氧化酶   半抑制浓度   黄酮   多酚   米氏方程  

摘要： 为了解槲皮素、芦丁、没食子酸及其与维生素C联用对黄嘌呤氧化酶(XOD)的抑制特性,本文通过建立黄嘌呤氧化酶体外抑制模型,以别嘌呤醇为阳性对照,测定这三种天然化合物在不同浓度下对XOD的抑制效果及抑制动力学。结果表明:三种物质对黄嘌呤氧化酶均有抑制作用,且具有浓度依赖性,其抑制效果与结构和本身性质有明显相关性,抑制作用强弱次序为槲皮素>芦丁>没食子酸,半抑制浓度IC50值分别为(5.51±0.41)μmol/L、(48.66±0.49)μmol/L、>200μmol/L;单一没食子酸抑制效果较弱,而没食子酸在维生素C的协同下,对XOD的抑制率从20.17%提高至40.96%,起到提高抑制效果和体系稳定性的双重作用;以上三种物质对XOD的抑制类型属于不同模式的非经典型混合抑制剂。本文对研究此类物质的抑制机理和应用有重要意义。

关键词： biotechnology   cellular agriculture   future visions   meat   spaces of production   the Anthropocene  

摘要： Set against the attention given to animal-agricultural geographies and animal agriculture's environmental impacts, proponents of cultured meat (i.e., biomass cultured from cells) and genetic modification-based "cellular-agricultural" technologies today promise that the production of animal products could become more sustainable if animals were taken out of the equation. Though future visions for such a shift have often centred on how much land could be saved through the deployment of new biotechnologies, proponents and researchers today increasingly also foreground the future economic geographies and sites of production that these should engender. In this paper I explore such envisioned geographies, building on 24 interviews with cellular-agricultural actors and on observations during meetings. Essentially echoing an ecomodernist embrace of the Anthropocene as a great opportunity, cellular-agriculturalists frequently promise that the technologies they advocate should offer the possibility to unfetter the production of animal products from spatial constraints. (Post-)animal products can now be produced anywhere. But in assuring that products and production processes should feel familiar, they frequently also describe a world where microbrewery-like facilities and transparent production processes supplant industrialised animal agriculture's remote slaughterhouses. Hence, a kind of craft-emphasising "recombinant" ecomodernism emerges. In exploring cellular-agricultural future visions, my aim is not to determine whether, or which, particular visions might be realised. Rather, I centre on descriptions of future spaces of production and economic geographies in order to explore contemporary biotech boosterism. Engaging with these visions, as well as the often unchronicled creative destruction that they could entail, thus allows me to contribute to an emerging set of texts that scrutinise the current and intended political economy (and ecology) of cellular agriculture, as w

关键词： Dry digestion   Modified Gompertz model   Response surface methodology   Microbial analysis   Life cycle assessment  

摘要： Despite the wide applications of dry anaerobic digestion (AD), a number of fundamental issues, such as composition-oriented estimation of biogas production and CO2 reduction potential, were not well understood yet. The objective of this study was to establish composition-oriented models for prediction of biogas production and the associated shift of microbial communities. Three important factors regarding feedstock, including loading, carbon-to-nitrogen ratio, and solid-to-liquid ratio, were found to significantly affect the biogas production. The biogas production and digestion kinetics were evaluated with the response surface methodology. The major contribution to biogas production was found to be hydrogenotrophic methanogens (82.6 +/- 0.4%). The net CO2 reduction potential was assessed from the life-cycle approach, and a substantial amount of CO2 generation (i.e., 2.8-6.7 tonne/tonne-VS) could be reduced by AD, compared to incineration, revealing that dry AD for food waste treatment should be one of the essential practices in the portfolio of global CO2 mitigation.

关键词： 4-chlorophenol wastewater   sludge performance   functional genes expression   sequencing batch bioreactor  

摘要： In this study, a lab-scale sequencing batch bioreactor (SBR) with hydraulic retention time (HRT) of 8 h was established to treat 50 mg/L 4-chlorophenol (4-CP), and the temporal responses of 4-CP on the performance and the expression level of related functional genes in sludge were explored. Results showed that after the SBR was acclimated with the cometabolic carbon sources of 4-CP and methanol, the pollutants were effectively degraded. The pollutants removal was influenced by the polysaccharides and proteins in sludge. The real-time PCR showed that except for the gene p450, the prompt removal of pollutants before 2 h caused the significant upregulation of the other functional genes from the genus Pseudomonas in sludge, while the downregulation occurred from 2 to 8 h with the progressive removal of pollutants in SBR cycle, indicating that the removal of pollutants was closely related to the functional genes expression.

关键词： Cellulase   Xylanase   DDGS   Submerged fermentation   Trichoderma reesei  

摘要： Most of the corn-ethanol plants use dry-mill process and generate large volume of distillers dried grains with solubles (DDGS) as the co-product. The DDGS is a promising feedstock with rich content of cellulose and xylan. The goal of this study was to optimize cellulase and xylanase production byTrichoderma reesei(NRRL 6156) using DDGS as the carbon source at shake-flask and validate the results at benchtop bioreactors. The fermentation medium containing varied amounts of dilute-acid pretreated DDGS, yeast extract, and peptone were optimized for maximal enzyme production at 30 degrees C, pH 5.0 and 180 rpm with 3% (v/v) inoculum using Box-Behnken response surface methodology (RSM). Co-production of xylanase and cellulase enzymes was not achieved in the same medium;higher DDGS hydrolysate favored cellulase enzyme only while lower amount induced the xylanase enzyme. Based on the RSM results, maximal xylanase of 18.5 IU/mL was predicted with 5% DDGS hydrolysate, 0.1 g/L yeast extract, and 2 g/L peptone, while maximal cellulase of 1.1 IU/mL was predicted with 20% DDGS hydrolysate, 1 g/L yeast extract, and 0.5 g/L peptone. Of the two developed models from shake-flasks, xylanase model validated successfully the fermenter results giving 18.7 IU/mL of experimental xylanase in 1.5-L working volume bioreactor. [GRAPHICS] .