Comparison of Lactic Acid Productivities at High Substrate Conversions in a Continuous Two-stage Fermenter With Cell Recycle Using Different Kinetic Models

The steady-state performance of a two-stage recycle fermenter with two different types (I and II) of configurations for staging was investigated numerically for the continuous production of lactic acid. In Type I the bleed broth withdrawn from the first stage is supplied to the second fermenter, and in Type II both filtrate and bleed broth from the first stage are introduced to the second stage. Using four different kinetic models taken from the literature, the effects of operating parameters on the overall lactic acid productivities and the overall substrate conversions are examined. At moderate conversions, productivities for Type I operation are found to be higher than those for Type II and for the single-stage system. In the case of high conversions close to complete consumption, Type II operation is more efficient than the Type I and single-stage systems. For 99% conversion and 40 kg m^-3 substrate feed concentration, productivities for Type II are predicted to be 14-74% higher compared to those for the single-stage system at the same bleed ratios.     

Trifluoromethanesulphonic acid catalysed transalkylation between tetrabromobisphenol-a and toluene for the production of 2,6-dibromophenol

The preparation of 2,6-dibromophenol is described. This compound, useful as raw material for brominated poly(phenyleneoxide) and pyrogallol or derived pharmaceuticals/pesticides, was prepared in 80% (isolated) yield by a transalkylation reaction between tetrabromobisphenol-A and toluene. The catalyst, trifluoromethanesulphonic acid, can be simply recovered and recycled. Perfluorinated resin sulphonic acid (NAFION-H®, DuPont) did not effectively catalyse this transalkylation.     

印制板蚀刻、微蚀刻废液的再生和铜回收的技术及设备

传统的印制板蚀刻废液处理方法存在着工艺落后、操作不便、二次污染、效益不高等问题,本工艺采用特殊的萃取电解、吸附电解技术,使蚀刻废液得以再生循环利用,铜得以100%回收,低含铜废水铜得到98%回收,整个系统不产生二次污染,获得的铜为高纯度铜板,在实现污染控制的同时,废液废水得到了资源化利用。     

浅议高校校园中水回用工艺

分析了高校校园中水回用的必要性,对位于市区和郊区新建高校提出了有针对性的校园中水回用工艺,并对中水回用项目的效益进行了探讨.     

Windows 8回收站取证分析

在计算机取证过程中,对于删除文件的分析常常提供有价值的信息。知道在哪里找到被删除文件并且能够理解文件被删除过程中产生的元数据,这是一个合格的计算机取证人员必备的素质。本文对Window 8系统的回收站与传统的Windows XP系统的回收站的相似点和不同点进行了对比分析,并详细说明了Windows 8系统回收站的工作细节,以期为计算机取证人员提供帮助。     

基于COM GIS的循环经济管理信息系统的设计开发*

组件式GIS是开发地理信息系统的最新技术手段,成为环境管理与GIS综合集成的首选工具。以Map—Objects为例,对基于组件式GIS开发循环经济管理信息系统的设计技术进行了分析,提出扩展系统开放性的方法,对信息查询、多源数据的图层处理及GIS与环境模型的集成途径进行了研究,结合程序代码,对如何实现系统功能进行说明,提出对循环经济管理中的特定对象进行动态跟踪的实现方法。     

苯乙酸溶解度测定及提取工艺研究

为了提取6-氨基青霉烷酸(6-APA)、7-ADCA生产过程中产生的副产物苯乙酸,采用物理法测定了苯乙酸在水、水-乙醇、水-丙酮中的溶解度及其在水中的溶解速率,由此确定了水法多次提取的工艺方案。结果表明,在提取温度(60±2)℃,时间10~15 m in,水用量1 500 mL,提取次数3~4次时,苯乙酸收率为90.8%,纯度为99.3%。该法污染少、成本低,所得PAA产品质量好。     

循环冷却水系统无垢低腐蚀率的技术改进

泸天化公司大氮肥循环冷却水系统投用以来，经优选水稳剂配方、改进加氯方式、增设旁滤池、提高补充水质量等措施，年腐蚀率从0．3366mm降至0．0241mm，换热器运行一年无结垢现象。     

呼和浩特石化公司凝结水回收改造工程总结

本文主要对呼和浩特石化公司凝结水回收系统改造前的状况、采取的改造措施及改造后的效果进行了总结，并就今后可能的改造作了预测分析。     

Ultra-high pressure sterilization of powdery food stuff—a new application of a roller compactor

A new non-heating technique was developed for the sterilization of food stuff. Applying a roller compactor, ultra-high pressure sterilization has experimentally demonstrated its ability to sterilize dry powders, such as corn flour and Chinese herbs, with little quality deterioration. Also, the degree of food sterilization was found correlated well with the linear press forces between the rollers, roller gaps, and number of compaction passes. In comparison to the conventional high pressure sterilization technique, the new dry continuous processing method has the advantage of lower investment cost and is more versatile for sterilizing various food powders.