Morphology and composition of particles emitted from conventional and alternative fuel vehicles

Size, morphology, and composition of airborne particles strongly affect human health and visibility, precipitation, and the kinetic characteristics of particles. In this study, the morphology and chemical composition of particles emitted from conventional (diesel and gasoline) and alternative (CNG and methanol) fuel vehicles were characterized through scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The SEM images revealed that the size of primary particles (without agglomeration) was approximately 10 nm in the exhaust from all the tested vehicles. The particles emitted from gasoline vehicle (GV), CNG vehicle (CNGV), and methanol vehicle (MV) had the same median diameter, 62 nm, which was smaller than those from heavy diesel vehicle (HDV) and light diesel vehicle (LDV). Soot was observed in the HDV, LDV, and GV samples but not in the CNGV and MV. The fractal dimension, which was used to quantify the degree of irregularity of soot, was 1.752 ± 0.014, 1.789 ± 0.076, and 1.769 ± 0.006 in the exhaust from HDV, LDV, and GV samples, respectively. The particles discharged by all tested vehicles contained the elements C, O, Fe, and Na. The main element in the samples of HDV, LDV, and GV was C, while O was the main element in the samples of alternative fuel vehicles. The profiles of minor elements were more complex in the emissions of alternative fuel vehicles than those in the emissions of conventional fuel vehicles. The results improved our understanding of the morphology and elemental composition of particles emitted from vehicles powered by diesel, gasoline, CNG, and methanol.

     

硫酸盐和Fe(Ⅱ)EDTA-NO/Fe(Ⅲ)EDTA厌氧还原过程特性及微生物群落分析

在生物法烟气脱硫技术(Bio-FGD)和络合吸收生物还原脱硝技术(BioDeNO_x)基础上,提出了生物结合络合吸收同步脱硫脱硝的工艺思路,该工艺利用加入Fe(Ⅱ)EDTA的碱性吸收液同时吸收烟气中的二氧化硫(SO_2)和一氧化氮(NO).本研究在厌氧反应器中实现烟气脱硫脱硝吸收产物硫酸盐和Fe(Ⅱ)EDTA-NO/Fe(Ⅲ)EDTA的同步去除.结果表明,水力停留时间为16 h,p H维持在7.0时,硫酸盐的平均去除率为95.16%,Fe(Ⅱ)EDTA-NO的平均去除率为96.61%.硫酸盐的还原产物主要以液相中硫离子和气相中硫化氢的形式存在,Fe(Ⅱ)EDTA-NO的最终还原产物为N2.反应运行的各个阶段均可实现Fe(Ⅲ)EDTA的还原,但还原率会随HRT降低而下降.第5阶段反应器中主要的硫酸盐还原菌为Desulfomicrobium,同时存在异养反硝化菌Pseudomonas与两种硫自养反硝化菌Sulfurimonas与Sulfurovum,并发现了两种具有还原单质硫功能的菌属Thermovirga与Mesotoga.     

Metal distribution characteristic of MSWI bottom ash in view of metal recovery

Bottom ash is the major by-product of municipal solid waste incineration(MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals(especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al,Fe, Cu and Zn were 18.9–29.2, 25.5–32.3, 0.7–1.0 and 1.6–2.5 g/kg, respectively. Moreover,44.9–57.0 wt.% of Al and 55.6–75.4 wt.% of Fe were distributed in bottom ash particles smaller than 5 mm. Similarly, 46.6–79.7 wt.% of Cu and 42.9–74.2 wt.% of Zn were concentrated in particles smaller than 3 mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation.     

Pseudomonas sp. ZXY-1, a newly isolated and highly efficient atrazine-degrading bacterium, and optimization of biodegradation using response surface methodology

Atrazine, a widely used herbicide, is increasing the agricultural production effectively, while also causing great environmental concern. Efficient atrazine-degrading bacterium is necessary to removal atrazine rapidly to keep a safe environment. In the present study, a new atrazine-degrading strain ZXY-1, identified as Pseudomonas, was isolated. This new isolated strain has a strong ability to biodegrade atrazine with a high efficiency of 9.09 mg/L/hr.Temperature, p H, inoculum size and initial atrazine concentration were examined to further optimize the degradation of atrazine, and the synthetic effect of these factors were investigated by the response surface methodology. With a high quadratic polynomial mathematical model(R~2= 0.9821) being obtained, the highest biodegradation efficiency of 19.03 mg/L/hr was reached compared to previous reports under the optimal conditions(30.71°C, pH 7.14, 4.23%(V/V) inoculum size and 157.1 mg/L initial atrazine concentration).Overall, this study provided an efficient bacterium and approach that could be potentially useful for the bioremediation of wastewater containing atrazine.     

基于环境因子和邻近信息的土壤属性空间分布预测

为探索乡镇尺度上土壤属性空间分布预测的最佳方法,以江西省万年县齐埠镇为例,借助四方位搜索法、地统计学和遥感影像分析技术提取环境因子（地形因子和植被覆盖指数）和邻近信息[w（有机质）与w（速效钾）],构建OK法（普通克里金法）、RK1法（仅基于环境因子的回归克里金法）以及RK2法（基于环境因子和邻近信息的回归克里金法）对齐埠镇耕地表层（0~20 cm）土壤w（有机质）、w（速效钾）空间分布进行预测.结果表明:齐埠镇土壤w（有机质）平均值为35.03 g/kg,w（速效钾）平均值为96.73 mg/kg,均为中等空间变异性.对62个样点进行建模,16个测试样点进行独立验证的误差分析表明,RK2法对土壤w（有机质）、w（速效钾）预测结果的均方根误差、平均绝对误差和平均相对误差较OK法分别降低了18.05%、18.01%、21.77%和7.25%、9.49%、9.84%;较RK1法分别降低了22.48%、20.91%、22.02%和9.27%、12.61%、13.52%.研究显示,RK2法明显提高了土壤w（有机质）、w（速效钾）空间分布模拟精度,并且存在改进和提高的空间.      

不同主体功能定位的县域空间功能区划研究

文章通过判别分析法,尝试构建一套针对不同主体功能定位县通用的指标体系,以反映社会经济发展状况、生态环境保护重要性、国土空间开发支撑条件。通过在广西10个不同主体功能定位县的实践应用,将县域空间划分为城镇空间、农业空间和生态空间,重点开发区、农产品主产区、重点生态功能区的城镇空间分别小于30%、20%和10%,农产品主产区的农业空间和重点生态功能区的生态空间均大于50%。研究成果为全省范围推广县域空间功能区划提供了科学依据。     

危险废物焚烧厂环境污染控制与风险管理水平评价指标体系研究与应用

采用德尔菲法、层次分析法和五分制综合评分法,构建了危险废物焚烧厂环境污染控制与风险管理水平评价指标体系。从选址、技术和管理的角度,制定了31个评价指标,并归纳为8个准则层指标群,通过计算权重和对评价指标的赋分,实现对危险废物焚烧厂环境污染控制与风险管理水平的量化评价。应用结果表明:华南某市两家危险废物焚烧厂的环境污染控制与风险管理水平分值分别为3.34和4.38,分别处于良好和先进的水平。     

煤制烯烃废水处理与回用技术解析

针对煤制烯烃项目废水的来源及水质特点,从生化处理技术与回用处理技术方面阐述了煤制烯烃废水处理现状及存在问题,展望了煤制烯烃废水处理与回用技术未来发展方向,指出了新型脱氮工艺、膜集成工艺及分质结晶技术在煤制烯烃废水处理中的可行性,为煤化工废水处理与资源化利用提供理论参考。     

利用餐厨垃圾湿热处理脱出液制备液态菌肥研究

以餐厨垃圾湿热处理脱出液为发酵培养基,选用圆褐固氮菌(Azotobacter chroococcum)作为实验菌种制作固氮液态菌肥。测定了圆褐固氮菌的主要生理特性,将其接种于餐厨湿热处理脱出液中进行培养,确定最佳发酵时间,并分别测定发酵的最佳初始p H值、接种量、培养温度、摇床转速、装液量、脱出液与水的混合比例。结果表明:圆褐固氮菌在餐厨湿热处理脱出液中最佳发酵时间为36 h,发酵最佳初始p H值、接种量、培养温度、摇床转速、装液量、脱出液与水的混合比例依次为7.5、1%、30℃、150 r/min、50 m L(250 m L锥形瓶)、1∶1。圆褐固氮菌在餐厨垃圾湿热处理脱出液中进行培养后,可达到液态菌肥的活菌数标准。     

β射线法与重量法监测环境空气PM_(2.5)的应用比较

重量法是测量PM_(2.5)的传统手工经典方法,而β射线法加动态加热系统联用光散射法作为自动在线监测技术的常用方法被广泛使用。将5030-SHARP型β射线法加动态加热系统联用光散射法PM_(2.5)自动监测设备监测结果与手工法测量结果进行比对、分析,结果表明:β射线法与重量法监测结果具有一致性,测量结果不存在显著性差异;β射线法与重量法相对偏差值与温度、相对湿度、风速等气象因子的相关性不明显;β射线法与重量法监测结果的差异性与PM_(2.5)质量浓度、季节等条件有关;随着PM_(2.5)质量浓度逐渐升高,β射线法与重量法相对偏差的绝对值|RD|也随之增大,不同季节的|RD|平均值差异较大,春季、冬季的|RD|平均值大于夏季、秋季。