新型结构内循环生物流化床的流体力学特性试验及数值模拟

建立小型试验模型,利用粒子成像测速(PIV)技术对模型4个工况的流场进行测量.然后对其中3个工况进行数值模拟,对数值模拟和试验测量结果进行分析比较,证明用数值计算方法来模拟生物流化床流体力学特性的可行性.     

大气细菌粒子与飘尘粒子的关系

本研究用ANDERSEN生物粒子采样器和光散射气溶胶粒子计数器,在北京西单和丰台对大气细菌粒子与飘尘粒子的浓度和浓度分布及两者之间的关系进行了观测。结果表明,大气细菌粒子的日平均浓度为2.882个/l,浓度分布是从第6级至第1级逐级增大;飘尘粒子的平均浓度为149464个/l,浓度分布是从0.5～32μm依次减小:大气细菌粒子浓度与≥2.0μm的飘尘粒子有非常明显的正相关关系。     

室内外空气真菌污染状况初探

用Ａｎｄｅｒｓｅｎ生物粒子采样器和平皿沉降法分别观测了室内和室外空气真菌粒子浓度，粒数中值直径和沉降量。结果表明，室外空气真菌粒子浓度高于室内空气真菌粒子浓度，室外空气真菌粒数中值直径大于室内空气真菌数中值直径，室外空气真菌粒子沉降量大于室内空气真菌粒子沉降量。     

“后桥”专机流水线排风除尘系统设计

通过治理某厂差动齿轮箱壳体流水线中各类机床在生产过程中产生的金属粉尘，介绍了排风除尘系统的吸尘罩设计，排风量计算，风管管路布置以及除尘器和风机的选用等，系统运行结果表明，达到设计要求。     

生物陶粒废水处理与回用技术研究

通过对生物陶粒工艺处理石油炼制废水技术的改进和研究,使出水不仅能够达到国家和地方排放标准要求,而且完全可以达到工业循环用水标准要求,取得了良好的经济效益和环境效益。     

Cation exchange capacities of soil organic matter fractions in a Ferric Lixisol with different organic matter inputs

Soil organic matter (SOM) has an important effect on the physicochemical status of highly weathered soils in the tropics. This work was conducted to determine the contribution of different SOM fractions to the cation exchange capacity (CEC) of a tropical soil and to study the effect of organic matter inputs of different biochemical composition on the CEC of SOM. Soil samples were collected from a 20-year-old arboretum established on a Ferric Lixisol, under seven multipurpose tree species: Afzelia africana, Dactyladenia barteri, Gliricidia sepium, Gmelina arborea, Leucaena leucocephala, Pterocarpus santalinoides, and Treculia africana. Fractions were obtained by wet sieving and sedimentation after ultrasonic dispersion. Relationships between CEC and pH were determined using the silver thiourea-method and were described by linear regression. The CEC of the fractions smaller than 0.053 mm was inversely related to their particle size: clay (<0.002 mm)>fine silt (0.002–0.02 mm)>coarse silt (0.02–0.053 mm), except for the soils under T. africana, D. barteri, and L. leucocephala, where the CEC of the fine silt fraction was highest or comparable to the CEC of the clay fraction. The clay and fine silt fractions were responsible for 76–90% of the soil CEC at pH 5.8. The contribution of the fine silt fraction to the CEC at pH 5.8 ranged from 35 to 50%, which stressed the importance of the fine silt fraction for the physicochemical properties of the soil. Differences in CEC between treatments for the whole soil and the fractions could be explained by the differences in carbon content. Except for the intercept for the clay fraction, SOM had a significant (P<0.001) contribution to both the intercepts (=estimated CEC at pH 0) and slopes (=pH-dependent charge) of the CEC–pH relationships for the whole soil and the fractions. The CEC of SOM at pH 5.8 varied between 283 cmol_c kg⁻¹ C for particulate organic matter, and 563 cmol_c kg⁻¹ C for the fine silt fraction. The biochemical composition of the organic inputs did not have an important effect on the CEC of SOM. In total, SOM was responsible for 75–85% of the CEC of these soils.     

Size effect of Pt nanoparticles in acid-assisted soot oxidation in the presence of NO

Pt/Al₂O₃ catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method, and the sulfated counterparts were prepared by impregnation of sulfuric acid. The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O₂ are positively correlated with the size of platinum. The sulfated Pt/Al₂O₃ exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO₂ production. Such a contradiction is more significant for those catalysts with smaller platinum particles. Herein, the catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), inductive coupled plasma (ICP) emission spectrometry, CO chemisorption, thermogravimetric analysis (TGA), NH₃ temperature-programmed desorption (NH₃-TPD), NO temperature-programmed oxidation (TPO) and NO_x temperature-programmed desorption (TPD). Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO₂ transfer efficiency onto the soot pushed by the acidic catalysts.     

Particle concentration effect in adsorption/desorption of Zn（Ⅱ） on anatase type nano TiO2

Adsorption/desorption in a new Zn(II)-TiO2 adsorption system was investigated at different particle concentrations (Cp). TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized (approximately 10 nm) pure anatase-type TiO2. Adsorption experiments were carried out with particle concentrations of 100, 400 and 1000 mg/L, and their adsorption isotherms were found to decline successively, showing an obvious Cp effect. Desorption experiments indicated that adsorption in this system was irreversible, and the irreversibility increased with increasing Cp. These phenomena could be explained by the MEA (metastable equilibrium adsorption) theory and the Cp effect could be modeled well with an MEA-Freundlich-type Cp effect isotherm equation. This study may help understand environmental behavior of contaminants on ultrafine natural particles.     

泡沫-细水雾对变压器油池火的冷却及热辐射阻隔特性研究

泡沫-细水雾在全尺寸变压器灭火实验中展现出高效灭火性能。纯水细水雾具有冷却效果好、热辐射阻隔能力强的特点,但添加泡沫灭火剂后对其冷却及热辐射阻隔特性的影响机制尚不明确。对泡沫-细水雾和纯水细水雾的冷却与热辐射阻隔特性进行了对比实验,并基于雾特性测试结果对相应性能的差异进行了分析。发现添加泡沫灭火剂后能降低水雾的粒径,从而令泡沫-细水雾的冷却和热辐射阻隔性能优于纯水细水雾。此外,泡沫灭火剂中的阻燃物质也是加速火焰熄灭的重要因素。研究结果可为变压器灭火系统选择、泡沫-细水雾系统工况参数优化等方面提供理论指导。     

Characterization of bacterial communities during persistent fog and haze events in the Qingdao coastal region

• Light haze had little effect on bacterial communities. • Fog and heavy haze had significant effects on these communities. • Air pollution exerted a greater influence than particle size on bacterial community. Here, we report the characteristics of bacterial communities in aerosols with different particle sizes during two persistent fog and haze events in December of 2015 and 2016 in Qingdao, China. In the early stage of pollution, the accumulation of PM_2.5 led to the accumulation of microorganisms, thus increasing the bacterial richness and diversity of fine particle sizes. With the persistence and aggravation of pollution, the toxic effect was strengthened, and the bacterial richness and diversity of each particle size decreased. When the particle concentration was highest, the richness and diversity were low for each particle size. Light haze had little influence on bacterial communities. The occurrence of highly polluted humid weather and heavy haze resulted in significant changes in bacterial community diversity, composition and structure, and air pollution exerted a greater influence than particle size on bacterial community structure. During persistent fog and haze events, with the increase of pollutants, bacteria associated with each particle size may be extensively involved in aerosol chemistry, but the degree of participation varies, which requires further study.