造纸废水混凝处理中SFT助凝替代性研究

中小造纸厂废水处理常用PAC作混凝剂 ,PAM作助凝剂。由于PAM成本很高 ,影响了处理设备的投运率。用超细滑石粉 (SFT)替代PAM助凝 ,与混凝剂PAC配合 ,其混凝处理效果基本相当 ,但是处理成本降低 0 .10元 /m3 。由于SFT属环境无害材料 ,不会给排泥带来二次污染     

Spectrophotometric Determination of Atmospheric Acidity by means of the Displacement of the Equilibrium of Acid-Base Indicators

A method is described for determining acidity by means of the spectrophotometric determination of the displacement of the equilibrium of açid-base indicators. The method is simple, sensitive and free of known interferences. There is no dependence on costly or sophisticated equipment and the results obtained are reliable and reproducible.     

The environmental significance of surface films II. Enhanced partitioning of Lindane in thin films of octanol on the surface of water

The log of the partition coefficient for Lindane between octanol and water at 22°C is 3.2; it is 3.9 if the octanol is in the form of a lens floating on the water, and it is 4.5 between an octanol monolayer and the underlying water.     

污泥淤砂分离器对分离分流污泥性质的影响

为解决我国很多城镇污水厂活性污泥的MLVSS/MLSS普遍偏低,污泥中泥沙淤积严重的问题,根据水力旋流器的分离原理,开发了污泥淤砂分离器,实现污泥中生物基质和淤砂的分离分流,研究污泥淤砂分离器主要结构参数排口比(底流口直径/溢流管直径)对分离分流污泥性质的影响。实验结果表明,排口比为0.4时,污泥经过污泥淤砂分离器后,得到的底流污泥MLVSS/MLSS比原污泥减小了34%,溢流污泥MLVSS/MLSS增大了16.8%,污泥中的生物基质富集在溢流污泥中,淤砂富集在底流污泥中;底流污泥浓度MLSS比原污泥增加了2.6倍,底流污泥SVI和CST分别减小了68%和70%,底流污泥浓缩效果明显,沉降性能和脱水性能大幅提高,有利于底流污泥的处理处置;进一步减小排口比,底流污泥浓缩效果、沉降性能和脱水性能均进一步提高。     

Optical properties of aerosols of mixed composition

A model is developed which relates the reduction in visual air quality to the chemical and physical properties of airborne aerosol particles. The aerosols are considered to be inhomogeneous and to have a mixed chemical composition which varies with particle size. The water content of the aerosol particles is derived from a semi-empirical application of the thermodynamic equations for particle growth. The model is valid for all ranges of relative humidity.The light scattering and absorption coefficients are calculated using Mie theory extended to concentric sphere scatterers. The core of each particle, which is primarily taken to be nonvolatile carbon, is enclosed in a water-soluble exterior. The soluble layer responds to changes in the relative humidity by absorbing (or releasing) water. The model predictions are in excellent agreement with experimental measurements made in Denver in the fall of 1978.     

Study of inclusion complex of beta-cyclodextrin and nitrobenzene

beta-cyclodextrin can react with nitrobenzene to form an inclusion complex which is characterized by (1)H NMR and powder X-ray diffractometry. The ratio of beta-CD to NB in inclusion complex is determined as 1:1. At 25 degrees C, the dissociated constant, K(D), of the inclusion complex is measured as 6.5 x 10(-3) M in neutral solution (pH=7.0), but in alkali (pH=13.5), K(D) is 3.2 x 10(-2) M which is much larger than that measured in neutral.     

活性炭三维电极法对印染废水的处理研究

对三维电极方法处理印染废水进行了实验研究,初步探讨了活性炭三维电极法处理印染废水的机理,对影响处理效果的各种要素,如反应时间、槽电压和pH值等进行了条件实验,得出了活性炭三维电极法处理印染废水的最佳运行条件为:停留时间120-180 min,槽电压25～30 V,进水pH值6.5～7.5。结果表明,该反应器能有效地降低废水色度,有较高的COD去除效率,并能提高印染废水的可生化性。     

Thermodynamics of binding of cadmium to bovine serum albumin

The binding isotherm of Cd2+ ion to bovine serum albumin (BSA) has been investigated by microcalorimetry at 310.15 K and pH 7.0. The thermodynamic parameters of the binding reaction have been determined, and the stoichiometry of the complex is 2:1, indicating that there exist two identical binding sites of BSA with Cd2+ ion. The value of deltarHthetam is -28.4+/-1.7 kJ mol(-1), the free energy of binding deltarGthetam is -25.2 kJ mol(-1), and the entropy of binding deltarSthetam is -10.3 J mol(-1) K(-1). The negative deltarHthetam and deltarSthetam values are observed for the binding reaction of Cd2+ ion and BSA, suggesting that the binding reaction is mainly enthalpy-driven and the entropy is unfavorable for it.     

测定高锰酸盐指数考核样品时的计算方法修正

针对测定高锰酸盐指数考核样品时的结果偏高现象，经过查找，其原因是由于按公式计算没有考虑稀释用纯水的空白值响应。经修正公式后计算，其考核样品的结果则均为正确。     

The prediction of the numbers of violations of standards and the frequency of air pollution episodes using extreme value theory

Extreme value theory is discussed in a manner suitable for scientists working in the air pollution area. The method of application of the theory is described by means of an example analysis on an ozone data set and the theory is applied to several data sets collected in Brisbane, Queensland, Australia. The theory is used to predict the number of violations of WHO and U.S. standards expected in the year following data collection. Comparison of these predictions with the relevant observations shows that the theory does quite well. Ways of using extreme value theory as an air quality management tool are suggested.     

Mineralization of CCl4 by the UVC-photolysis of hydrogen peroxide in the presence of methanol

A method for a photochemically induced mineralization of CCl4 is described in which use is made of reductive radicals. The UVC-photolysis (254 nm) of H2O2 added to aqueous solutions of CCl4 is leading to the homolysis of the oxidant yielding hydroxyl radicals (HO) that subsequently react with added methanol to generate hydroxymethyl radicals (CH2OH). The latter radicals initiate mineralization of CCl4 by reductive C-Cl bond splitting. CHCl3, C2Cl4 and C2Cl6 were found as reaction intermediates, but are quantitatively depleted in a parallel oxidative reaction manifold leading to mineralization. Carbon dioxide radical anion, CO2(-), an intermediate in the mineralization pathway of methanol, is also shown to initiate the mineralization of CCl4 by reductive dechlorination. A reaction mechanism is proposed and validated with computer simulations of all the experimental results.     

垃圾焚烧炉炉膛温度的影响因素

垃圾焚烧过程的不稳定会导致大量有害物质的生成,为确保垃圾的清洁燃烧需要将炉膛温度控制在850℃以上,为此测试了焚烧炉运行的主要可控参数对炉膛温度的影响。结果表明,垃圾堆放位置在垃圾池深3～8 m处,并经过6 d以上发酵脱水后适合焚烧;炉膛温度随给料量、一次风率和一次风温增加而增大,随过量空气系数增加而降低,其中给料量宜控制在95%～110%之间;当过量空气系数为1.6、一次风率为90%、一次风温为260℃、给料量为100%时炉膛温度达901℃。     

Environmental Persistence of Chemicals

- DOI: http://dx.doi.org/10.1065/espr2006.01.008 Background The hazard criterion of persistence as it applies to chemicals in the environment is reviewed and discussed. This quantity can not be measured directly in the environment, thus it must be estimated using models that synthesise information on chemical half-lives and partitioning properties, the nature of the environment and how the chemical is released into the environment. Main Features It is suggested that the preferred criterion is the average residence time of the chemical in the environment, i.e. conceptually the sum of the life-times of all molecules (attributable only to losses by degrading reactions) divided by the number of molecules. If all chemical fate processes are first order, this persistence is independent of the quantity of chemical introduced and whether introduction is steady- or unsteady-state in nature. It is shown that in a multimedia environment persistence is affected not only by degradation kinetics, but also by mode-of-entry and partitioning. For screening level purposes a Level II equilibrium model may be adequate but a Level III model is generally preferable for estimating the average persistence. If a distribution of persistences is required a dynamic Level IV model must be used. Discussion The implications for regulating chemicals on the basis of persistence are discussed. Conclusion It is concluded that the preferred strategy is to use Level II, III, and IV models and that the use of only degradation kinetics or media-specific half-lives can be misleading and uneconomical.     

Determination of sources of atmospheric aerosol in Copenhagen based on receptor models

A statistical analysis is presented of atmospheric aerosol element composition data collected at five monitoring stations in Copenhagen in 1983. The objective is to identify sources of air pollution, to estimate the variation of total suspended particles (TSP) for the different sources and to calculate the annual average source contribution to TSP. The basis for analysis is the chemical mass balance equations. Factor analysis methods are used to identify major sources of pollution and the contribution from each of the sources to the variation in TSP is estimated by an additional multiple regression. Finally, the influence of serial correlations between daily element contributions is discussed and it is stressed that the result of the analysis is not seriously affected by these correlations.     

Degradation reactions of a carbamate herbicide, chlorbufam: effect of soil factors

Kinetics of degradation of chlorbufam is determined in aqueous solution, in aqueous solution with humic acids, argilo-humic complexes, soil and sterile soil. The adsorption is also evaluated in this different fractions. The adsorption process has a protecting effect and the chlorbufam is not chemically degraded when it is adsorbed on organic matter. The biodisponibility is also decreased by adsorption.