反渗透膜面细菌胞外多聚物提取方法研究

城市污水脱盐系统的反渗透(RO)膜面生物污堵问题严重影响了该技术的稳定运行,解析生物污堵机理的关键因素是微生物胞外多聚物(EPS)特征分析,然而目前细菌EPS提取方法多样,无统一标准,制约了EPS分析的可靠性和可对比性.基于此,本文以再生水厂RO膜面污堵物中分离的细菌为对象,采用水浴、超声、离子树脂、碱液4种方法提取EPS,以DOC和DNA含量表征提取的EPS总量和提取过程细胞破裂程度.结果表明,45℃水浴法不造成细胞破裂,提取总量多,是一种有效的提取方法.进一步对比不同提取时间条件下EPS溶液中多糖和蛋白含量变化,以及分子量、荧光特征等,综合认为提取1 h时,提取的EPS中多糖与蛋白相对含量稳定,不同分子量化合物均溶于水中,能客观地反映EPS特征.研究表明,45℃水浴1 h可以作为细菌EPS提取的适用方法应用.     

Determination of organochlorine and organophosphate pesticide residues in fruits,vegetables and sediments

Abstract

A method is described for the determination of organochlorine and organophosphate pesticide residues in fruits, vegetables and sediments. The concentrated solvent extract was sealed in a polymeric membrane tube, dialysed in cyclohexane and the solvent replaced with hexane. The organophosphates were analysed on a specific thermionic detector without further clean‐up. For the organochlorine pesticides the extract was eluted through 3 g of alumina and analysed on GC/ECD. The clean‐up for sediment extract was carried out on a10 g alumina column with 100 mL hexane containing 5% acetone and the eluate was concentrated to 5 mL.

The detection limit for organophosphates on a 40 g sample and a final volume of 10 mL was on the average 0.01 mg/kg. The detection limit for organochlorine pesticides, with the final volume of 25 mL, was 0.005 mg/kg for all pesticides except for p,p'‐DDT and endosulfan sulphate, which was 0.01 mg/kg.

The detection limit for oganochlorine pesticides in sediment, with the final volume of 2 mL, was less than 1 μg/kg and for organophosphate pesticides less than 10 μg/kg when the final volume was made to 0.5 mL. At the detection limits the method produced a very high coefficient of variation for both organochlorine and organophosphate pesticides.     

Genotoxicity of chromium in vitro on yeast: Interaction with DNA†

The genotoxicity of chromium chloride was investigated in cells of D₇ strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase.

A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer.

The experiments with ⁵¹Cr radiotracer demonstrated that Cr³⁺ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl₃ that cause some damages to cytoplasmatic membrane.     

膜生物反应器及其组合工艺在有机废水处理中的应用

膜生物反应器是一种膜与生物反应器相结合的废水处理新工艺。介绍了膜生物反应器的种类，特性及其组合工艺。综述了国内外用于有机物废水处理过程中的研究进展及应用现状，并对其发展前景作出了展望。     

膜生物反应器废水处理新工艺

概述了国内外膜生物反应器的研究与应用状况；介绍了其构形与特点；分析了膜污染的成因，影响因素及防制措施；指出了今后的研究方向。     

超滤技术在废水处理中的应用

文章对超滤原理、超滤膜种类、国内外超滤技术发展现状等做了较详尽的阐述,同时着重介绍了超滤技术在油田含油废水、石化含油废水、金属加工用乳化废液、纤维加工油剂废水及羊毛精制废水中回收羊毛脂的应用实例。     

Recovery of gold by chicken egg shell membrane-conjugated chitosan beads

We have successfully prepared a bead-type adsorbent from two materials with different adsorption characteristics. Heavy metals were removed by greatly swollen egg shell membrane-conjugated chitosan beads. The egg shell membrane accumulated and removed precious metal ions from a dilute aqueous solution with a high affinity in a short contact time. Experiments suggested that chitosan beads could take up gold ions with great capacity and selectivity by conjugation with egg shell membrane. Under certain conditions, the selective removal of gold and copper in a mixture of gold and copper ions by egg shell membrane-conjugated chitosan beads was 100% and 2%, respectively. Egg shell membrane-conjugated chitosan beads can be seen as a promising material to recover gold in wastewater from various industries, such as electroplating.     

中空纤维膜应用于烟气脱硫的现状与前景

本文介绍了中空纤维膜的基本情况,概述了中空纤维膜烟气脱硫技术的研究现状,并对其发展前景进行了展望。     

饮用水除氟技术研究的新进展

综述了近年来国内外饮用水除氟技术的研究新进展，介绍了沉淀、吸附和膜分离三种处理工艺的热点研究——电凝法、载镧改性吸附法和唐南透析法的基本原理和发展动态，并分析了各自的优缺点。认为开发高效、低成本、易操作和安全的饮用水新型除氟技术是目前的研究重点和方向。     

表面过滤技术在焚烧厂烟气脱酸净化中的作用

随着城市垃圾焚烧工程的发展，国家对焚烧后尾气的处理技术提出了越来越高的要求。基于“表面过滤”理论的Gore过滤技术，不但为粉尘排放达到欧洲标准提供了技术保障，而且为脱酸／硫的后续反应提供了反应界面，在实际应用中可以有效节约反应剂。