Simultaneous nitrification and denitrification in activated sludge system under low oxygen concentration

Simultaneous nitrification and denitrification (SND), which is more economical compared with the traditional method for nitrogen removal, is studied in this paper. In order to find the suitable conditions of this process, a mixed flow activated sludge system under low oxygen concentration is investigated, and some key control parameters are examined for nitrogen removal from synthetic wastewater. The results show that SND is accessible when oxygen concentration is 0.3–0.8 mg/L. The nitrogen removal rate can be obtained up to 66.7% with solids retention time (SRT) of 45 d, C/N value of 10, and F/M ratio of 0.1 g COD/(g MLSS·d). Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs. Translated from Environmental Pollution and Control, 2004, 26(1): 11–13 [译自: 环境污染与防治]     

用二阶闭合理论确定的大气扩散系数的分析

本文分析了作者以前得到的一种扩散系数的某些结果,认为这种扩散系数解释了垂直湍流和风切变的联合作用使水平扩散增大的实验观测结果;建立了与雷诺应力间的函数关系,在简化情况下,与泰勒理论得到的结论类似。在边界层低层,湍流扩散系数与粘性系数是不相等的,有时会有较大差别。     

浅析迷宫斜板沉淀理论与应用效果分析

根据煤矿矿井水的水质特点,对迷宫斜板的工作原理及效果进行粗浅分析,论述了迷宫斜板在矿井水中的应用,探讨了矿井水处理站迷宫斜板沉淀池的沉淀效率、沉淀时间、占地面积及悬浮物浓度等参数的变化,为煤矿矿井水的深度净化处理提供了可供选择的处理方式之一。     

协同论、城市生态学及苏州河综合整治

从协同论和城市生态学的角度，对苏州河综合整治的定义、目的、方式进行了阐述了探讨。     

生物法净化低浓度挥发性有机废气的动力学问题探讨

依据对生物膜填料塔净化低浓度甲苯废气过程的生物化学反应类型、过程控制因素和生物膜作用等机理问题的分析研究，定义其为一个以生物膜为有效吸附表面、以活菌体为生物反应活化中心的吸附生物化学反应过程，并据此建立了“吸附生物膜”理论及相应的动力学模式．该模式计算值与实验值之间有较好的相关性（相关系数Ｒ＞０．９５）．结果将为相关的理论研究和实际操作研究提供有益的资料．     

基于统一强度理论的松散岩体的围岩压力计算

对于软弱破碎岩体,在埋深较浅的情况下,可以采用太沙基理论计算围岩压力。破裂面两侧作用着摩擦力,采用统一强度理论考虑破裂面两侧的摩擦力,从应力传递概念出发,推得了作用于衬砌上的垂直围岩压力公式。计算结果表明强度理论的效应是明显的。本文给出了围岩压力的范围值。     

也谈对环境的损害--欧盟《预防和补救环境损害的环境责任指令》的启示

欧盟于2004年3月通过了一项预防和补救环境损害的环境责任指令,鲜明地将"环境损害"这一定义规定在该指令中,并且针对环境损害规定一系列预防和补救措施,具有较强的前瞻性.审视国内相关理论和立法,具有一定的滞后和欠缺.鉴于环境立法具有相当强的可借鉴性,围绕该指令进行相关理论和立法上的探讨.     

粉末金属压制过程建模方法(1)--金属塑性力学方法

介绍了建立描述粉末金属压制过程数学模型的难点．详细论述了目前4种主要的建模方法，分析、比较了各种方法的优劣，并对建模工作提出了展望和指导性意见。     

粉末金属压制过程建模方法(2)--广义塑性力学方法和内蕴时间方法

介绍了建立描述粉末金属压制过程数学模型的难点，详细论述了目前4种主要的建模方法，分析、比较了各种方法的优劣，并对建模工作提出了展望和指导性意见。     

Studies on metabolism of 2-naphthylamine and its activation mechanism

2-naphthylamine was incubated with induced rat liver microsome S9 preparation and the metabolites were separated through HPLC. The following products were identified: 2-amino-5-naphthol, 2-amino-6-naphthol, 2-amino-7-naphthol and 2-amino-8-naphthol. The yields of these four metabolites are varying in quantity, and the relative contents of 2-amino-8-, -5-, -6- and -7-naphthol are 52.6%, 28.5%, 14.0% and 4.9% respectively. These results are consistent with the quantitative HMO calculation and inference based upon Di-region theory, i.e., the metabolisms of aryl amines on extra-ring (assigned the ring without the substituent of amino group) are through the epoxidation and then NIH shift, but are not the direct hydroxylation in the formation of phenols. It is shown that both the amino group and the carbon atoms on the extra-ring play duality roles of activation and detoxification in metabolism.