微波再生载苯酚活性炭过程中再生产物分析

研究了载氮气和无载气2种条件下,微波再生载苯酚活性炭过程中再生产物的成分和苯酚随再生过程的去向分布。结果表明,无载气时,微波功率越高,再生反应器内温度越高,吸附质的高温裂解反应越彻底,再生产物以挥发性气体为主,有机质种类很少;而当微波功率较低或载氮气再生时,反应器内温度相对较低,苯酚难以被彻底分解,再生产物中含多种复杂的链状或环状有机物。此外,载氮气时,经气提、挥发而去除的苯酚量约占总吸附量的一半,再生炭上无苯酚残留,活性炭吸附性能可完全恢复乃至优化;无载气时,经挥发而去除的苯酚量只有19.9%,其余大量苯酚则在微波作用下裂解或缩合为其他物质随尾气而去除,且再生炭上仍有少量苯酚未被解吸出来。因此,前者活性炭再生的效果优于后者。     

降解SO2功能菌的16S rRAN基因测序及降解特性

用低浓度SO2诱导驯化方法获得高效脱硫菌群,并用分离培养与16S rRNA基因测序技术相结合的方法鉴定菌群种属,分析驯化过程中种群结构的动态变化,同时研究分离纯菌种的脱硫性能。结果表明,从诱导驯化7 d和14 d菌液中分别分离出23株菌和22株菌,16S rRNA序列分析发现这些菌归属于13个种,其中有6个种(Rhodococcus erythropolis、Pseudomonas putida、Microbacterium oxydans、Sphingomonas koreensis、Acinetobacter junii、Acinetobacter johnsonii)对SO2-3有较强的降解能力,并在持续驯化过程中稳定的生长传代,降解产物以硫酸根为主,还有极少量的单质硫。与含混合菌的驯化菌液降解SO2-3的能力相比,单一脱硫菌的脱硫性能较弱。脱硫功能菌株及其基本特性的研究为微生物处理SO2烟气提供了丰富的菌源信息和理论基础。     

厌氧系统中碱处理对污泥减量的影响

碱解预处理污泥和原污泥按一定比例进行混合后,投入厌氧反应器中进行消化,研究其对污泥减量化的影响。结果表明,该处理既可以提高污泥减量率,又能改善污泥厌氧消化性能,提高污泥产气量。当碱处理污泥和原污泥混合比为1∶3时,在混合初期由于稀释作用和水解中和作用,溶液的pH能迅速恢复到中性。SS减少48%,较对照组提高了10%;SCOD减少约80%,较对照组提高20%,而空白对照组因未发生溶胞作用,各参数值均处于较低水平,降解率也维持在较低水平。     

基于CGE模型的环境灾害经济影响评估——以湖南雪灾为例

环境灾害(比如,气象灾害、荒漠化等)不仅仅造成直接损失(比如,厂房、设备破坏和粮食欠收等),而且会导致经济系统产业链中断,进而影响到区域经济的正常运行。本文以2008年南方雨雪冰冻灾害为例,基于CGE模型,评估交通中断对湖南省的间接经济影响。为刻画灾害冲击,CGE模型的改进包括:为反映灾害的区域性,将全国CGE模型降尺度为区域模型;为反映灾后应急情景,选择资本市场宏观闭合规则为资本在部门之间不流动;为反映货物周转量变化,在生产模块增加效率参数;为反映旅客周转量变化,选择劳动力宏观闭合规则为新古典闭合。研究表明:①对于重大环境灾害,间接经济损失甚至比直接损失大;②2008年雪灾引起的湖南省交通瘫痪,造成的间接经济损失为50.4亿元(以增加值表示),约占湖南省前两个月GDP的3%;③值得注意,由于产业之间相互关联,简单叠加各产业单独破坏造成的经济损失,往往夸大整个行业同时破坏造成的经济损失。     

Inorganic Acid Emission Factors of Semiconductor Manufacturing Processes

Abstract

A huge amount of inorganic acids can be produced and emitted with waste gases from integrated circuit manufacturing processes such as cleaning and etching. Emission of inorganic acids from selected semiconductor factories was measured in this study. The sampling of the inorganic acids was based on the porous metal denuders, and samples were then analyzed by ion chromatography. The amount of chemical usage was adopted from the data that were reported to the Environmental Protection Bureau in Hsin-chu County according to the Taiwan Environmental Protection Agency regulation. The emission factor is defined as the emission rate (kg/month) divided by the amount of chemical usage (L/month). Emission factors of three inorganic acids (i.e., hydrofluoric acid [HF], hydrochloric acid [HQ], and sulfuric acid [H₂SO₄]) were estimated by the same method. The emission factors of HF and HCl were determined to be 0.0075 kg/L (coefficient of variation [CV] = 60.7%, n = 80) and 0.0096 kg/L (CV = 68.2%, n = 91), respectively. Linear regression equations are proposed to fit the data with correlation coefficient square (R²) = 0.82 and 0.9, respectively. The emission factor of H₂SO₄, which is in the droplet form, was determined to be 0.0016 kg/L (CV = 99.2%, n = 107), and its R² was 0.84. The emission profiles of gaseous inorganic acids show that HF is the dominant chemical in most of the fabricators.     

Decomposition of Gas Phase 1,3-Butadiene by Ultraviolet/Ozone Process

Abstract

A pilot-scale plug-flow reactor was built to investigate its performance in treating airborne 1,3-butadiene (BD) via ozonation (O₃) and ultraviolet (UV)/O₃ technologies. Governing factors, such as the initial molar ratio of ozone to BD, UV volumetric electric input power, and moisture content in the influent airstream, were investigated. Experiments were conducted at an influent BD concentration of ～50 ppm, an ambient temperature of 26 °C, and a gas retention time of 85 sec. Results show that an initial molar ratio of ozone to BD of 3.5 and 2 sufficed to obtain BD decompositions of >90% for ozonation and UV/O₃, respectively. The UV irradiance did not directly promote the decomposition of BD, rather, it played a role in promoting the production of secondary oxidants, such as hydroxyl radicals. Kinetic analyses indicate that both types of BD decomposition are peudo–first-order with respect to BD concentrations. Moisture content (relative humidity = 40–99%) and UV volumetric electric input power (0.147 and 0.294 W/L) are both factors that weakly affect the rate of BD decomposition. Economic evaluation factors, including both energy of ozone production and UV electric input power, were also estimated.     

Predicting Cutoff Aerodynamic Diameter and Sharpness of Single Round-Nozzle Impactors with a Finite Impaction Plate Diameter

Abstract

This investigation numerically examined the cutoff aerodynamic diameter (da₅₀) and the sharpness (GSD) of the particle collection efficiency curve of impactors with a finite impaction plate diameter. Results revealed that the inertial impactors have a limited cutoff aerodynamic diameter at different air velocities. The extreme value of the cutoff aerodynamic diameter increases with the nozzle diameter (W)/the plate diameter (D_c). The computed da₅₀/D_c values of the impactors increase with W/D_c at various Reynolds numbers (Re) and with the nozzle-toplate distance (S)/D_c when Re is 100. The value of GSD slightly increases with W/D_c for Re of 10 and 100, although the effect of S/D_c on GSD is not evident at various Res. The particle collection efficiency curve of the impactor with a lower Re is less sharp than that with a high Re at various W/D_c and S/D_c values. Statistical equations closely fitted the obtained numerical results for Res of 10–3000. The equations are useful for directly calculating the cutoff aerodynamic diameter and the sharpness of the particle collection efficiency curve for single round-nozzle impactors with a finite impaction D_c.     

Phthalate exposure in pregnant women and their children in central Taiwan

Phthalate exposure was found to be associated with endocrine disruption, respiratory effects, reproductive and developmental toxicity. The intensive use of plastics may be increasing the exposure to phthalates in Taiwanese population, particularly for young children.We studied phthalate metabolites in pregnant women and their newborns in a prospective cohort from a medical center in Central Taiwan. One hundred maternal urine samples and 30 paired cord blood and milk samples were randomly selected from all of participants (430 pregnant women). Eleven phthalate metabolites (MEHP, 5OH-MEHP, 2cx-MEHP, 5cx-MEPP, 5oxo-MEHP, MiBP, MnBP, MBzP, OH-MiNP, oxo-MiNP, and cx-MiNP) representing the exposure to five commonly used phthalates (DEHP, di-isobutyl phthalate (DiBP), DnBP, BBP, DiNP) were measured in urine of pregnant women, cord serum and breast milk after delivery, and in urine of their children. Exposure was estimated with excretion factors and correlation among metabolites of the same parent compound. Thirty and 59 urinary samples from 2 and 5 years-old children were randomly selected from 185 children successfully followed.Total urinary phthalate metabolite concentration (geometric mean, μg L⁻¹) was found to be higher in 2-years-olds (398.6) and 5-years-olds (333.7) than pregnant women (205.2). Metabolites in urine are mainly from DEHP. The proportion of DiNP metabolites was higher in children urine (4.39 and 8.31%, ages 2 and 5) than in adults (0.83%) (p < 0.01). Compared to urinary levels, phthalate metabolite levels are low in cord blood (37.45) and milk (14.90). DEHP metabolite levels in women’s urine and their corresponding cord blood are significantly correlated. Compared to other populations in the world, DEHP derived metabolites in maternal urine were higher, while phthalate metabolite levels in milk and cord blood were similar. The level of phthalate metabolites in milk and cord blood were comparable to those found in other populations. Further studies of health effects related to DEHP and DiNP exposure are necessary for the children.     

Polybrominated diphenyl ethers (PBDEs) and indicator polychlorinated biphenyls (PCBs) in marine fish from four areas of China

The levels of polybrominated diphenyl ethers (PBDEs) and indicator polychlorinated biphenyls (PCBs) were determined in marine fish from four areas of China (South China Sea, Bohai Sea, East China Sea, and Yellow Sea) using GC/NCI-MS and GC/ITMS, respectively. Total concentrations of eight PBDEs (BDE-28, 47, 99, 100, 153, 154, 183 and 209) in all samples ranged from 0.3 ng g⁻¹ ww (wet weight) to 700 ng g⁻¹ ww, with median and mean values of 85 ng g⁻¹ ww and 200 ng g⁻¹ ww, respectively. BDE-209 and BDE-47 were the major congeners in all samples, contributing 54% and 19% to the total concentration, respectively. The sum of seven indicator PCB levels (CB-28, 52, 101, 118, 138, 153, and 180) ranged from 0.3 ng g⁻¹ ww to 3.1 μg g⁻¹ ww, with median and mean values of 6.4 ng g⁻¹ ww and 398 ng g⁻¹ ww, respectively. High contributions of CB-138 (32%) and CB-153 (25%) were found in all samples. In general, pollutants measured in this study were at high levels when compared with previous studies from other regions in the world. The relative abundance of BDE-209 may suggest that deca-BDE sources existed in studied area. And principal component analysis (PCA) showed that there were other PBDE sources in Yellow Sea. The pattern and PCA showed that PCB pollutions came from similar sources in the studied areas. In addition, concentrations of ∑₇PBDEs (u/209) were strongly correlated with those of ∑₇PCBs in all fish (r = 0.907, n = 44).     

农村生活固体垃圾的处理现状及影响因素

随着我国农村经济与农民收入水平的快速提高,农村生活固体垃圾产生与排放的数量快速增加,已经严重影响了农村环境、农民健康和农业可持续发展.该文的主要目的是基于甘肃和河北省60个村和240个农户的调研资料,深入了解农村生活固体垃圾的处理和管理现状及影响生活固体垃圾有效处理的制约因素.结果表明,大多数村没有处理生活固体垃圾的设施,总体看甘肃省拥有的处理设施要好于河北省.超过一半的村中生活固体垃圾都没有人管理,但部分村开始制定相关的管理计划.描述性统计分析和计量模型的分析结果表明,农村生活固体垃圾的处理状况与农民人均收入水平的提高和交通便利程度的改进有显著正相关关系,而非农就业机会的增加不利于当地生活垃圾的处理.