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1.
两阶段控制甘油浓度提高1,3-丙二醇发酵水平   总被引:7,自引:0,他引:7  
克雷伯氏菌(Klebsiella pneumoniae)分批发酵生产1,3-丙二醇(1,3-PD),根据菌体生长、产物生成和补料可将发酵过程分成4个阶段.不同阶段控制不同的底物浓度会对菌体生长和产物生成产生不同的影响.研究发现,菌体生长阶段(阶段Ⅱ)底物浓度控制在6.0 g/L最适合菌体生长,产物主要生成阶段(阶段Ⅲ)底物浓度控制在18.9 g/L最适合产物生成,菌浓可达7.83 g/L,最终1,3-PD的浓度为68.5 g/L,摩尔转化率为61%,生产强度为2.21 g/(L·h).  相似文献   

2.
报道了拟茎点霉P2-139 (Phomopsis sp.P2-139 )在前期培养基质优化的基础上,进行的10,50和200 L发酵罐中培养条件和中试放大的研究结果.在10 L发酵罐中,P2-139菌株的最佳发酵培养基为:马铃薯240 g/L,葡萄糖75 g/L,陈海水20%(体积分数),pH自然.机械剪切力对去乙酰真菌环氧乙酯的产生和产量影响不大.临界氧浓度和KLa测定结果表明,P2-139菌株生长的溶氧浓度(DO)值应维持在20%~30%以上才能保证菌株的正常生长和代谢;200 L罐中试放大DO值的控制为:发酵初期(0~96 h)20%以上,发酵中期(96~216 h)28%以上,发酵后期30%~60%;发酵基质为:马铃薯180 g/L,葡萄糖60 g/L,陈海水20%(体积分数),pH自然;发酵后期流加葡萄糖使残糖质量浓度控制在10 g/L左右.在此条件下,去乙酰真菌环氧乙酯的产量可达120 mg/L以上.  相似文献   

3.
溶解氧对垃圾压缩站废水同时硝化反硝化脱氮的影响   总被引:12,自引:0,他引:12  
溶解氧(DO)含量是实现同时硝化反硝化生物脱氮的关键因素之一.文中采用同时好氧厌氧生物反应器(SOA),对反应器内不同DO含量下垃圾压缩站废水中氨氮(NH4+-N),CODcr和总氮(TN)含量随时间的变化情况进行了考察.发现DO含量对反应器内CODcr,NH4+-N和TN的去除效率和效果均有较大的影响.在DO含量(质量浓度,下同)为1.0mg/L时,反应器内的氨氮去除可分为快速和慢速两个阶段.在DO含量为0.5 mg/L时反应器内出现好氧区和厌氧区平衡状态,同时硝化反硝化脱氮效果最佳.反应器内可能存在一定的厌氧氨氧化脱氮过程.  相似文献   

4.
针对微藻固碳过程中藻液产生的高浓度溶氧会抑制藻细胞生长、降低CO2固定效率的问题,搭建了管式光生物反应器实验台用于藻类的高效培养和固碳,提出了利用电化学方法抑制藻液中溶氧效应的研究思路。首先开展管式光生物反应器培养小球藻的实验研究,对比了光生物反应器与锥形瓶2种培养装置对小球藻生长特性的影响,其次实验研究了利用碱性阴离子交换膜燃料电池的阴极氧还原反应去除藻液中的溶解氧。结果表明:管式光生物反应器运行10个周期之后,微藻的质量浓度达到769mg/L,生物量增长了10倍,培养效果明显优于锥形瓶培养;经过系统持续运行4h之后,藻液中的溶氧量由18.35mg/L降低到6.19mg/L,溶氧消耗效率为66.3%,电池的最大功率密度达到81 W/m2。研究证明,采用燃料电池的阴极电化学反应可以实现藻液中溶解氧快速有效地消耗,这一方面提升了微藻的固碳效率,另一方面输出了电能,降低了系统能耗。  相似文献   

5.
采用三角摇瓶来摸索菌种BL21(DE3)/pET3C-aSCAIF表达目的蛋白的最优发酵条件,并在此基础上在Biotop CF-5L自动控制发酵罐中,利用补料分批培养技术,流加甘油,进行发酵培养.摇瓶培养最优条件:2%接种量、25 mL LB培养基、37℃培养、0.5%的甘油做碳源,接种后4 h加入终浓度为0.5 mmol/L的IPTG,诱导4 h后目的蛋白表达量最高.菌种在Biotop CF-5L自动控制发酵罐中的条件为:以10%的接种量接种到2.5 L发酵培养基中,设定溶氧30%,pH7.0,温度37℃,通气量3 L/min,流加甘油15 g,培养4 h后,加入终浓度为0.5 mmol/L的IPTG,诱导4 h后终止发酵,发酵罐中获得的菌体量为62.1 g.  相似文献   

6.
短程硝化反应器的快速启动与运行特性   总被引:5,自引:0,他引:5  
为了探讨快速启动和运行特性,以硝化污泥接种序批式反应器,在纯自养条件下利用短程硝化处理高NH4 -N废水。实验结果表明,控制溶解氧(d isso led oxygen,DO)浓度为0.5 m g/L、游离氨浓度11.8~49.1 m g/L时,反应器的启动在第13 d完成。在曝气量为800 mL/m in时,利用pH与DO的变化趋势来判断氨氧化进程,控制每周期曝气时间为6.0 h,反应器稳定运行了101个周期。NH4 -N平均去除率为82.6%,NH4 -N去除负荷最大为0.97 kg/(m3.d),NO2--N平均累积率达97.2%,NO3--N浓度小于10 m g/L。在反应器中利用纯自养微生物可以长期稳定地实现短程硝化反应。  相似文献   

7.
以模拟废水为处理对象,通过两级序批式生物膜反应器SBBR串联工艺模拟实验.确定系统好氧阶段溶解氧浓度DO3.5mg/L,进水pH7.0~7.2,论述了生物膜的培养驯化过程,并以处理出水指标达到国家排放标准为主要原则确定反应系统的最优运行工况:1号反应器瞬间进水、好氧6h、沉淀30min、排水5min、2号反应器瞬间进水、厌氧搅拌4h、好氧3h、沉淀20min、排水排泥5min.单周期运行时间为14h.经过两级SBBR处理后最终出水达到国家排放标准.  相似文献   

8.
利用溶氧作为控制信号补料分批培养生产PHA的研究   总被引:3,自引:0,他引:3  
利用已构建的工程菌Escherchia coli XL1-Blue(pKSABC),在20L自动发酵罐里进行补料分批培养。研究表明,底物浓度、温度、pH、DO等参数是影响菌体生长和PHA积累的重要因素;通过补料分批培养可以提高PHA的积累量。通过对DO在发酵过程中的变化规律的分析,确定DO作为补料时间的在线控制信号。补料的原则是,使发酵前期菌体大量生长,发酵后期PHA大量积累。在优化条件下,对工程菌Escherchia coliXL1-Blue(pKSABC)进行了60 h的补料分批培养,菌体浓度、PHA浓度和PHA占细胞干重的百分比分别为179g/L,132g/L,73.7%。  相似文献   

9.
普通活性污泥富集好氧氨氧化菌试验   总被引:8,自引:0,他引:8  
用普通活性污泥在SBR反应器中富集好氧氨氧化菌,反应器的运行周期为1 d,瞬间进水,曝气21.5 h,沉淀2 h,排水0.5 h.pH控制在7.8~8.3,DO控制在0.8~1.2 mg/L,温度控制在30±2℃.采用人工配水,初始人工配水中NH 4-N的浓度为50 mg/L.待稳定后逐渐增加进水氨氮浓度至250 mg/L,每次增加幅度50 mg/L.为定量判定富集过程中好氧氨氧化菌数目的增长情况,每隔15 d对SBR反应器中的污泥进行最大可能计数法(MPN法)测试和MLSS测试.富集培养120 d后,好氧氨氧化菌浓度提高300倍.对比试验证实,pH和温度对好氧氨氧化菌的富集有明显影响.  相似文献   

10.
通过控制膜生物反应器(MBR)中溶解氧(DO)浓度、碳氮比(C/N)、污泥浓度(MLSS)和水力停留时间(HRT)等摸索了实现同步硝化反硝化的工艺条件,同时对好氧反应器中实现同步硝化反硝化的机理进行了探讨.化学需氧量(COD)在250 mg/L左右,C/N为10~30∶1,MLSS为5 g/L,HRT为5.0 h,DO为0.6~0.8 mg/L时,总氮去除率达86.0%,取得了良好的总氮去除效果,表明由于好氧反应器中缺氧区的存在,控制好操作条件可以实现同步硝化反硝化.体系中氨氮、硝态氮浓度的变化与总氮去除的关系说明短程反硝化现象的存在,而且在实现同步硝化反硝化过程中发挥着重要的作用.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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