新型含氮消毒副产物的生成机制及毒性研究进展

含氮消毒副产物(N-DBPs)具有很高的生物毒性和致癌性,近年来受到广泛关注。本文对目前N-DBPs的研究进展进行了概述,重点总结了典型N-DBPs包括卤乙腈(HANs)、卤代硝基甲烷(HNMs)、卤代乙酰胺(HAcAms)和亚硝胺(NAs)的生成机制;并归纳了N-DBPs的毒性效应和毒性机制。根据N-DBPs的生成途径,应该重点控制水中含胺类氮源前体物,并优化设计消毒剂种类和投加方式,在控制病原体的前提下,尽量削减高毒性N-DBPs的生成。本研究旨在为控制消毒副产物生成、提高饮用水水质提供理论参考。     

Ultraviolet degradation of methyltins: elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

The photodegradation of methyltins, as environmental pollutants, has scarcely been studied so far because of the shortage of rapid and sensitive speciation methods, even though they have very simple structures. The photodegradation of monomethyltin trichloride (MMT), dimethyltin dichloride (DMT) and trimethyltin chloride (TMT) was studied with our new developed HPLC-FPD hyphenated system, which enables rapid and sensitive detection of methyltins. The half-life times and kinetic rate constants of their degradation at different pH were calculated. The results suggest that MMT, DMT and TMT can be degraded under the UV irradiation rapidly at different pH, with a degradation rate sequence of TMT相似文献   

T-RFLP detection of nitrifying bacteria in a fluidized bed reactor of achieving simultaneous nitrification-denitrification

Steady simultaneous nitrification-denitrification (SND) was achieved in a fluidized bed reactor (FBR) by the control of DO concentration without physical separation of the aerobic and anoxic zones. The performance and composition of nitrifying bacteria were examined in this study. The ammonium removal efficiency was higher than 80% and the DO concentration (1-5 mg l(-1)) had little influence on it. More than 50% total nitrogen (TN) removal efficiency was achieved when DO was less than 3 mg l(-1) and in many cases the removal efficiency varied between 60-70%. The volumetric loading of TN varied between 0.12 and 0.20 kg Nm(-3)d(-1). 16S rRNA-based terminal restriction fragment length polymorphism analysis was used to characterize the diversity and distribution of the ammonia oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the FBR. The results indicated that, the composition and number of both AOB and NOB changed with position in the reactor and operating time. Nitrosomonas sp. was found to be dominant species of the AOB community, and Nitrobacter sp. also existed in the system. The SND mechanism in the FBR was proved to be the vertical stratification of active populations; however, the presence of microenvironments within the biofilm cannot be ruled out.     

用城市污水处理厂剩余污泥制备脱硝催化剂

以城市污水处理厂剩余污泥为原料,采用氧化锌和硝酸铁化学浸渍、高温热解制备脱除NOx的催化剂。用微型气固相催化反血装置考察了该催化剂在NH3选择性催化还原NO中的应用效果及寿命。实验结果表明：存350～450℃时的催化活性较高,在400℃时NO的最大转化率可达98．3％;催化剂的活性良好,经660min的活性测试,催化剂的活性只降低了约3％。对该催化刹进行了X射线衍射、热重和扫描电镜分析,分析结果表明,该催化剂含有丰富的金属元素及碳元袤,具有丰富的孔结构和晶体结构,而且表面及孔隙间负载的活性粒子较多,这些特征也表叫该催化刺具订良好的催化忡能。     

降雨径流时农田沟渠水体中氮、磷迁移转化规律研究

为有效阻控降雨条件下农田土壤流失氮、磷通过沟渠进入水体,通过对降雨时农田排水沟渠系统中总氮、总磷的测定和分析,研究降雨径流下沟渠系统水体中氮、磷的迁移转化规律和时空分布.结果表明,农田排水沟渠系统本身不太稳定,在外界条件(降雨)的作用下可以引起一系列的变化,同时农田排水沟渠系统又具有抗冲击可修复能力,可以使氮、磷的各项转化作用恢复.该特征使得总氮、总磷在沿程迁移过程中表现出一定的变化规律:总氮浓度沿程呈3次多项式曲线变化,总磷浓度整体呈指数递减变化;同时各断面的总氮、总磷自身转化也有其降解规律,总氮和总磷浓度随时间均呈3次多项式曲线变化.     

氮添加对侵蚀退化红壤化学性质及芒萁叶功能性状的影响

蕨类植物芒萁(Dicranopteris dichotoma)是我国南方红壤侵蚀区重要的水土保持植物,但目前氮添加对芒萁叶功能性状及其基部土壤化学性质以及这二者之间关系的影响尚不清楚.以芒萁作为研究对象,采用盆栽实验,设置CK(0 g m-2 a-1)、N1(1.1 g m-2 a-1)、N2(2.3 g m-2 a-...     

油田酸化作业井硫化氢防治措施探讨

硫化氢是一种无色、剧毒气体,属于一级危害物质,在安塞油田酸化作业中,部分井产生硫化氢。为保证酸化时现场作业人员的安全,本文介绍了安塞油田酸化作业过程中H2S气体的产生机理,并从化学角度分析H2S气体防治措施,为降低酸化作业安全风险提供技术保障。     

铁路线路坡度对列车运行能耗的影响分析

基于列车运行功能转化方程,分析铁路线路坡度对列车运行能耗的影响,阐述线路坡度起伏、拔起高度、节能坡等选线设计要素对列车运行能耗的影响机理,得出坡度对列车运行能耗影响显著、线路起伏在相应的"临界坡度"值以下对列车运行能耗无影响、拔起高度与下坡坡段长度比值可近似判别线路方案的节能状态等结论,以期为铁路线路选线提供能耗影响方...     

基于GIS的城市抗震防灾规划信息管理系统

探讨GIS在城市抗震防灾规划中的应用模式和关键技术,设计了城市抗震防灾规划信息管理系统的基本框架,并结合郑州新区抗震防灾规划工作,介绍了城市抗震防灾规划综合数据库、震害预测分析模型以及GIS辅助决策系统的研究与实现,为规划编制和实施提供重要的数据支撑和决策依据。