Latent hydraulic reactivity of blended cement incorporating slag made from municipal solid waste incinerator fly ash

The reactivity of cement pastes made by blending Portland cement with slag from municipal solid waste incinerator (MSWI) fly ash was investigated to assess the potential of recycling MSWI fly ash slag. The slag, prepared by melting MSWI fly ash at 1400 degrees C for 30 min, was pulverized and ground, then blended with ordinary Portland cement (OPC), using various substitution levels to make slag-blended cement (SBC). The pozzolanic reactivity of the ecocement was then characterized by determining variations in the compressive strength, degree of hydration, microstructure, speciation, and mineralogical crystalline phases. The results suggest that the strength of the pastes at an early age decreased with increasing substitution levels, whereas the strength at a later age of the tested pastes (with substitution levels less than 10%) outperformed OPC paste because of typical SBC properties. The development of strength at a later age was also confirmed by X-ray diffraction and scanning electron microscopy techniques. This implies that active silica (Si) and alumina (Al) react with the hydration product, calcium hydroxide (Ca(OH)2), to form calcium silicate hydrate (C-S-H), which contributed to strength development at a later age by the filling up of pores in the SBC pastes. The pozzolanic activity of the SBC pastes indicates that it is suitable for use as a substitute for OPC in blended cement.     

固体废弃物轮胎的热解技术

综述了国内外对废轮胎的处理状况，并详细地讨论了废轮胎热解技术的发展、分类以及典型工艺流程。热解技术主要包括油化技术、气化技术和炭化技术三种，并可制得衍生油、燃料气、碳黑等产品。分析了废轮胎热解工艺存在的问题，指出了如何开发环境友好的集成工艺是废轮胎热解工艺的发展方向。     

染料废水脱色混凝剂(PSDC-Ⅰ) 的制备和效果实验

研究了由固体废物 (炼铁废渣 )制取的含有多种金属离子的染料废水脱色混凝剂 (PSDC Ⅰ ) ,试验了它对染料废水的脱色效果及对印染废水的混凝效果 ,并与PAC进行了比较。考察了影响PSDC Ⅰ混凝及脱色效果的因素。结果表明 ,pH值在 6— 10范围内 ,PSDC Ⅰ具有良好的混凝效果。PSDC Ⅰ的两个最佳脱色区为 pH值 6— 8和 pH值 13左右。与PAC相比 ,PSDC Ⅰ不仅具有良好的混凝效果而且具有良好的脱色效果     

Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China

Spatial distribution of chlorinated hydrocarbons [chlorinated pesticides (CPs) and polychlorinated biphenyls (PCBs)] and polycyclic aromatic hydrocarbons (PAHs) was measured in riverine and estuarine sediment samples from Pearl River Delta, China, collected in 1997. Concentrations of CPs of the riverine sediment samples range from 12 to 158 ng/g, dry weight, while those of PCBs range from 11 to 486 ng/g. The CPs concentrations of the estuarine sediment samples are in the range 6-1658 ng/g, while concentrations of PCBs are in the range 10-339 ng/g. Total PAH concentration ranges from 1168 to 21,329 ng/g in the riverine sediment samples, whereas the PAH concentration ranges from 323 to 14,812 ng/g in the sediment samples of the Estuary. Sediment samples of the Zhujiang River and Macao harbor around the Estuary show the highest concentrations of CPs, PCBs, and PAHs. Possible factors affecting the distribution patterns are also discussed based on the usage history of the chemicals, hydrologic condition, and land erosion due to urbanization processes. The composition of PAHs is investigated and used to assess petrogenic, combustion and naturally derived PAHs of the sediment samples of the Pearl River Delta. In addition, the concentrations of a number of organic compounds of the Pearl River Delta samples indicate that sediments of the Zhujiang river and Macao harbor are most likely to pose biological impairment.     

Effect of experimental factors on nitrobenzaldehyde photoisomerization

The objective of this study was to compare the effect of various experimental factors on the photoisomerization of nitrobenzaldehyde. The experimental factors included light source, light energy, exposure time, light path distance and the concentration of nitrobenzaldehyde. The results showed that the photoisomerization of nitrobenzaldehyde increased with increasing light exposure. Different light sources and light path distances demonstrated significant impact on the reaction rate constants and half-lives of nitrobenzaldehyde. Although the light energy of UV photoreactor was 47% lower than that of xenon photoreactor, quantum yield and UV/VIS absorption pattern confirmed the finding that the effect of ultraviolet photoreactor on nitrobenzaldehyde was similar to that of xenon photoreactor with the light path of 17 cm. It was caused by the shorter wavelength of UV photoreactor mainly on 254 nn. The product of nitrobenzaldehyde photoisomerization, nitrosobenzoic acid, was detected from samples after 5 or 10 min exposure of three light sources. The concentrations of nitrosobenzoic acid increased with the increasing of exposure time up to 20 or 60 min.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

环磷酰胺等三种化学物诱发褐斑大蠊染色体畸变分析

染色体的畸变分析是一种简便易行,经济的遗传毒理学方法,可用来探讨诱变物对生物遗传系统的影响。目前人们多利用鼠类、赤麂及人的培养细胞来进行染色体畸变分析,其它材料很少见,蜚蠊(俗称蟑螂)是一种重要的卫生昆虫,也是一种较好的遗传学研究材料,其分布广泛,与人的日常生活环境密切相关,能否利用它作为一种污染的监测因子呢?我们利用褐斑大蠊(Periplaneta brunnea,Burmeister 1838)进行了初步尝试。     

一种新型烟气脱硫技术在燃煤锅炉上的扩大试验

介绍了用硫化碱加TFS添加剂进行燃煤锅炉煤气脱硫并副产硫代硫酸钠的中试成果。     

Transport modeling of copper and cadmium with linear and nonlinear retardation factors

The predictive accuracy of using the one-dimensional advection–dispersion equation to evaluate the fate and transport of solute in a soil column is usually dependent on the proper determination of chemical retardation factors. Typically, the distribution coefficient (K_d) obtained by fitting the linear sorption isotherm has been extensively used to consider general geochemical reactions on solute transport in a low-concentration range. However, the linear distribution coefficient cannot be adequately utilized to describe the solute fate at a higher concentration level. This study employed the nonlinear equilibrium-controlled sorption parameters to determine the retardation factor used in column leaching experiments. Copper and cadmium transportation in a lateritic silty-clay soil column was examined. Through the explicit finite-difference calculations with a third-order total-variation-diminishing (TVD) numerical solution scheme, all results of the theoretical copper and cadmium breakthrough curves (BTCs) simulated by using the Freundlich nonlinear retardation factors revealed good agreement with the experimental observations.     

Determination of source contributions to ambient PM2.5 in Kaohsiung, Taiwan, using a receptor model

Ambient particulates of PM2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM2.5. The mean concentration of ambient PM2.5 was 42.69-53.68 micrograms/m3 for the sampling period. The abundant species in ambient PM2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO4(2-) (12.8-15.1%), NO3- (8.1-10.3%), NH4+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO4(2-) and NO3-), and outdoor burning of agriculture wastes (13-17%).