溶气气浮过程动力学模型的分形观

凝聚/絮凝过程中形成的絮体通常具有分形几何结构,导致絮体的密度、渗透性发生了变化,从而对于固液分离过程(沉淀、气浮和过滤)带来很大的影响。本文基于前人对于絮体分形的研究成果,建立了絮体与微气泡之间接触碰撞的动力学方程、絮体/微气泡聚集体在水中上升的分形速率方程。絮体与微气泡间的相对尺度和流态的不同会有不同的碰撞机制,相应的动力学方程式与絮体的分形维数也有不同的关系。     

散射光下铁(Ⅲ)-丙酮酸盐配合物还原铬(Ⅵ)的研究

研究了在散射光下铁（Ⅲ）-丙酮酸盐配合物对铬（Ⅵ）的光还原反应;考察了溶液pH、铁（Ⅲ）、丙酮酸钠、铬（Ⅵ）浓度对反应的影响;分析了铬（Ⅵ）光还原反应的动力学。实验结果表明：铁（Ⅲ）-丙酮酸盐配合物体系能在较弱的散射光下还原铬（Ⅵ）。在铬（Ⅵ）浓度为19．2μmol／L、铁（Ⅲ）浓度为10．0μmol／L、丙酮酸钠浓度为240μmol／L、pH为3．0、光照240min的条件下,铬（Ⅵ）的还原率达到99．7％。从表观动力学方程的反应级数看,铁（Ⅲ）的级数（0．83）最高,铁（Ⅲ）浓度是影响铬（Ⅵ）光还原反廊速率的主要因素．铁（Ⅱ）是铬（Ⅵ）光还原的主要还原剂。     

电催化氧化法处理阴离子表面活性剂废水

采用自制电化学反应器对阴离了表面活性剂废水的电催化氧化处理进行了研究,考察了阳极材料、电解电压、电解时间、电极间距离、废水pH、废水电导率等对阴离子表面活性剂电解去除效果的影响,确定了最佳的处理条件。在电解电压为8V、电解时间为30～40min、电极间距离为2cm、废水pH为8～10、废水电导率为0．620ms／cm的条件下,阴离子表面活性剂的电解处理去除率可达96％以上。     

高活性絮凝剂产生菌群的构建、培养及应用研究

从筛选到的絮凝剂产生菌中构建出能比单一菌群产生更高絮凝活性的复合菌群——复合菌群1（BAFRT4＋CYGS1）．为降低复合菌群1的培养成本,尝试用啤酒废水替代葡萄糖作为培养基中的碳源和能源并获得成功．在优化培养条件下,复合菌群1所产MBF的絮凝活性达96.8％．复合菌群1所产MBF对靛蓝印染废水有良好的处理效果,最大CODCr去除率和脱色率分别达79．2％和87．6％．     

构筑安全环境建好奥运场馆--当前锁具市场分析

北京申办2008年奥运成功举国欢腾,如何建好奥运场馆举世瞩目.我们作为从事高保安智能锁具研制多年的中国科技工作者深感有义不容辞的责任,愿借此机会与大家交流,以求建好奥运场馆,推进高保安锁具发展.     

Enhanced organic phosphorus detection in sediments by foam separation and 31P-NMR

Phosphorus (P) is both a nutrient and a pollutant. For instance, excess P induces water eutrophication followed by death of fishes and other water life. Determination of organic P content in sediments is therefore important to study P cycling and environmental pollution. The most widely used method to determine organic P in sediments is NaOH–EDTA extraction followed by ³¹P-NMR detection. However, some organic P compounds are difficult to extract using NaOH–EDTA due to the low solubility, thus can not be detected by ³¹P NMR. Here, we used foam separation to determine organic P in sediment of North Canal of Tianjin City, China. Organic P was first enriched using foam separation coupled with NaOH extraction. The enriched organic P was then analyzed with ³¹P NMR. The results showed that, compared with the traditional extraction method, foam separation coupled with NaOH extraction enriched more P compound because ³¹P NMR detected an extra signal of teichoic acid at chemical shift 1.14. This teichoic acid signal was not detected in the extract prepared using only NaOH–EDTA. Our finding demonstrates that determination using foam separation followed by ³¹P NMR is feasible.     

Alteration of dominant cyanobacteria in different bloom periods caused by abiotic factors and species interactions

Freshwater cyanobacterial blooms have drawn public attention because they threaten the safety of water resources and human health worldwide. Heavy cyanobacterial blooms outbreak in Lake Taihu in summer annually and vanish in other months. To find out the factors impacting the cyanobacterial blooms, the present study measured the physicochemical parameters of water and investigated the composition of microbial community using the 16S rRNA gene and internal transcribed spacer amplicon sequencing in the months with or without bloom. The most interesting finding is that two major cyanobacteria, Planktothrix and Microcystis, dramatically alternated during a cyanobacterial bloom in 2016, which is less mentioned in previous studies. When the temperature of the water began increasing in July, Planktothrix appeared first and showed as a superior competitor for M. aeruginosa in NO₃^?-rich conditions. Microcystis became the dominant genus when the water temperature increased further in August. Laboratory experiments confirmed the influence of temperature and the total dissolved nitrogen (TDN) form on the growth of Planktothrix and Microcystis in a co-culture system. Besides, species interactions between cyanobacteria and non-cyanobacterial microorganisms, especially the prokaryotes, also played a key role in the alteration of Planktothrix and Microcystis. The present study exhibited the alteration of two dominant cyanobacteria in the different bloom periods caused by the temperature, TDN forms as well as the species interactions. These results helped the better understanding of cyanobacterial blooms and the factors which contribute to them.     

问一问:食品安全吗?

现在一说起食品,神经不免会抽动、会紧张,脑子里一片茫然,不知道食品中又会出现啥问题,真不知道吃什么才可以放心。回顾2005年,食品安全问题不断亮起红灯,苏丹红、孔雀石绿、奶粉碘超标、库存奶回用、早产奶、甲醛啤酒、致癌的保鲜膜,韩国泡菜被检出寄生虫卵,亨氏、肯德基、雀巢、立顿等跨国公司的食品也被质疑,让人目瞪口呆, 直冒冷汗。“民以食为天”。当下人们的平常食品和进口名牌食品会有如此之多的问题, 而有问题的食品为什么会充斥市场,很     

Two-step harmless treatment of secondary aluminum dross (SAD) by vacuum distillation and alkaline roasting

Journal of Material Cycles and Waste Management - Secondary aluminum dross (SAD) is classified as hazardous waste by many countries in the world because it contains a large number of toxic and...     

硫酸盐还原菌包覆矿石控制酸性废水排放及碳源的优选研究

本研究基于实验室筛选、培养的硫酸盐还原菌(Sulfate-reducing bacteria,简称SRB)菌群,分别考察以麦芽糊精、污泥、乙醇、乳酸钠等为碳源时SRB的生长状况,同时模拟野外环境进行柱淋滤实验,分析在不同碳源作用下原位控制酸性矿山废水的效果.结果表明,采用这4种碳源时,SRB还原硫酸盐能力的大小依次为:...