In-vehicle Measurement of Ultrafine Particles on Compressed Natural Gas, Conventional Diesel, and Oxidation-catalyst Diesel Heavy-duty Transit Buses

Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older models, but particle number reduction has not been verified in the research. Recent studies suggest that particle number is a more important factor than particle mass in determining health effects. In-vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning.     

Monitoring of Aerial Pollutants Emitted from Swine Houses in Korea

This on-site survey study was performed to determine the concentrations and emissions of aerial contaminants in the different types of swine houses in Korea and then to present beneficial information available for Korean pig producers to manage optimal air quality in swine house. The swine houses investigated in this research were selected based on three criteria; manure removal system, ventilation mode and growth stage of swine. Mean concentrations of aerial pollutants in swine houses were 8 ppm for ammonia, 300 ppb for hydrogen sulfide, 2 mg m⁻³ for total dust, 0.6 mg m⁻³ for respirable dust, 4 log(cfu m⁻³) for total airborne bacteria and 3 log(cfu m⁻³) for total airborne fungi, respectively. Mean emissions based on pig (liveweight; 75 kg) and area (m²) were 250 and 340 mg h⁻¹ for ammonia, 40 and 50 mg h⁻¹ for hydrogen sulfide, 40 and 50 mg h⁻¹ for total dust, 10 and 15 mg h⁻¹ for respirable dust, 1.0 and 1.3 log(cfu) h⁻¹ for total airborne bacteria and 0.7 and 1.0 log(cfu) h⁻¹ for total airborne fungi, respectively. In general concentrations and emissions of gases were relatively higher in the swine houses managed with deep-pit manure system with slats and mechanical ventilation mode than the different swine housing types whereas those of particulates and bioaerosol were highest in the naturally ventilated swine houses with deep-litter bed system.     

Carrousel氧化沟单个表曝机流态的模型试验和分析比较

对仅安装1个倒伞形表面曝气机(简称表曝机)的Carrousel氧化沟模型进行了水力学测定,通过颗粒动态分析仪(PDA)系统分析流出和流入表曝机一侧的液体流动速度、沉降速度,以及固体含量分布.结果表明,流出表曝机一侧,距表曝机较近的x轴位置流速较大;沉降速度沿y轴有个转折点,位于沟壁与挡板的中间;远离单个表曝机,固体含量逐渐增大.并将单个表曝机的测量结果与氧化沟内安装2个表曝机的流动试验进行比较,发现2个表曝机所产生的流场与单个表曝机产生的流场差别较大,且2个表曝机所产生的流场更稳定.      

Use of Chitosan as Coagulant to Treat Wastewater from Milk Processing Plant

Chitosan is a natural high molecular polymer made from crab, shrimp and lobster shells. When used as coagulant in water treatment, not like aluminum and synthetic polymers, chitosan has no harmful effect on human health, and the disposal of waste from seafood processing industry can also be solved. In this study the wastewater from the system of cleaning in place (CIP) containing high content of fat and protein was coagulated using chitosan, and the fat and the protein can be recycled. Chitosan is a natural material, the sludge cake from the coagulation after dehydrated could be used directly as feed supplement, therefore not only saving the spent on waste disposal but also recycling useful material. The result shows that the optimal result was reached under the condition of pH 7 with the coagulant dosage of 25 mg/l. The analysis of cost-effective shows that no extra cost to use chitosan as coagulant in the wastewater treatment, and it is an expanded application for chitosan.     

固体微粒气溶胶灭火剂的改性研究

固体微粒气溶胶灭火剂作为一种新型灭火剂具有优越的抑制火灾的性能,但其应用和推广的关键在于降低灭火气溶胶形成时的温度.本文利用TG方法分析了灭火剂的热分解过程,并通过测定固体微粒气溶胶灭火剂的释放速度、释放区温度分布及灭火性能,研究了固体微粒气溶胶灭火剂的降温消焰技术.同时对气溶胶的成分和固体粒子粒度分布进行了分析.     

Lead particle size and its association with firing conditions and range maintenance: implications for treatment

Six firing range soils were analyzed, representing different environments, firing conditions, and maintenance practices. The particle size distribution and lead (Pb) concentration in each soil fraction were determined for samples obtained from the backstop berms. The main factors that were found to influence Pb fragment size were the type of soil used to construct the berms and the type of weapon fired. The firing of high velocity weapons, i.e., rifles, onto highly angular soils induced significant fragmentation of the bullets and/or pulverization of the soil itself. This resulted in the accumulation of Pb in the finer soil fractions and the spread of Pb contamination beyond the vicinity of the backstop berm. Conversely, the use of clay as backstop and the use of low velocity pistols proved to be favorable for soil clean-up and range maintenance, since Pb was mainly present as large metallic fragments that can be recovered by a simple screening process. Other factors that played important roles in Pb particle size distribution were soil chemistry, firing distance, and maintenance practices, such as the use of water spray for dust suppression and deflectors prior to impact. Overall, coarse Pb particles provide much easier and more cost-effective maintenance, soil clean-up, and remediation via physical separation. Fine Pb particles release Pb more easily, pose an airborne Pb hazard, and require the application of stabilization/solidification treatment methods. Thus, to ensure sustainable firing range operations by means of cost-effective design, maintenance, and clean-up, especially when high velocity weapons are used, the above mentioned factors should be carefully considered.     

青海湖湖水性质、颗粒物沉积通量季节和年际变化——来自沉积物捕获器的研究

本文通过在青海湖南盆沉积中心试验性放置的Mark 8-13型时间序列沉积物捕获器所收集到的为期15个月的自然沉降颗粒物,分析了颗粒物沉积通量和物质组成,结合温盐传感器（CTD）所记录湖水参数数据的分析,讨论了青海湖上部10 m左右湖水中所发生沉积作用的季节与年际变化特征及其与环境参数的相互关系。结果表明,采集期间所沉降的总颗粒物具有显著季节和年际变化特征,其平均年沉降通量为112 g·m^-2·yr^-1,其组成主要是自生碳酸盐（高Mg方解石、文石）、生物壳体（介形虫、硅藻等）等内生作用形成的物质,以及少量的碎屑矿物。与实时监测的湖水参数比较表明,具有显著季节和年际变化的青海湖内生物质通量变化主要受控于夏季温度的变化。其沉积机制为：湖水温度的升高,有利于高Mg方解石和文石等自生矿物从碳酸盐过饱和的碱性湖水中结晶沉淀（盐度降低）,也有利于藻类和介形虫等微体生物大量繁殖,表现为温度偏高的2010年比2011年具有较低的湖水盐度和高得多的沉积通量。因此,青海湖自生碳酸盐沉淀通量可以用来反映湖水盐度和/或温度的变化,尽管这些内生作用形成的物质可能只约占到湖底沉积物的5%~20%。为更全面地了解青海湖现代沉积过程,有必要在更多点位、不同的深度进行长期放置捕获器和实时监测湖水参数变化。     

基于RBF和PSO的双喉道气动矢量喷管优化设计

本文探索了一种能多变量综合优化的方法,即对喷管进行参数化设计后,用均匀试验设计(UED)将试验样本均匀散布在设计区间内,求出各性能参数后,利用径向基神经网络(RBF)对试验样本进行拟合,再用粒子群算法(PSO)对训练好的神经网络进行寻优,找出了更好的双喉道气动矢量喷管设计参数组合。数值模拟结果显示,优化后的双喉道气动矢量喷管的矢量角有了明显提高。试验表明这种优化方法具有很好的优化能力,可以用来对喷管几何外形进行参数优化。      

Influence of MBBR carrier geometrical properties and biofilm thickness restraint on biofilm properties, effluent particle size distribution, settling velocity distribution, and settling behaviour

The relatively poor settling characteristics of particles produced in moving bed biofilm reactor (MBBR) outline the importance of developing a fundamental understanding of the characterization and settleability of MBBR-produced solids. The influence of carrier geometric properties and different levels of biofilm thickness on biofilm characteristics, solids production, particle size distribution (PSD), and particle settling velocity distribution (PSVD) is evaluated in this study. The analytical ViCAs method is applied to the MBBR effluent to assess the distribution of particle settling velocities. This method is combined with microscopy imaging to relate particle size distribution to settling velocity. Three conventionally loaded MBBR systems are studied at a similar loading rate of 6.0 g/(m² •day) and with different carrier types. The AnoxK™ K5 carrier, a commonly used carrier, is compared to so-called thickness-restraint carriers, AnoxK™ Z-carriers that are newly designed carriers to limit the biofilm thickness. Moreover, two levels of biofilm thickness, 200 μm and 400 μm, are studied using AnoxK™ Z-200 and Z-400 carriers. Statistical analysis confirms that K5 carriers demonstrated a significantly different biofilm mass, thickness, and density, in addition to distinct trends in PSD and PSVD in comparison with Z-carriers. However, in comparison of thickness-restraint carriers, Z-200 carrier results did not vary significantly compared to the Z-400 carrier. The K5 carriers showed the lowest production of suspended solids (0.7 ± 0.3 g-TSS/day), thickest biofilm (281.1 ± 8.7 µm) and lowest biofilm density (65.0 ± 1.5 kg/m³). The K5 effluent solids also showed enhanced settling behaviour, consisting of larger particles with faster settling velocities.     

The influence of aggregation of latex particles on membrane fouling attachments & ultrafiltration performance in ultrafiltration of latex contaminated water and wastewater

The goal of the present study was to investigate the influence of latex particle aggregation on membrane fouling attachments and the ultrafiltration performance of simulated latex effluent using Cetyltrimethyl Ammonium Bromide(CTAB) as a cationic surfactant. Hydrophilic polysulfone and ultrafilic flat heterogeneous membranes, with molecular weight cut off(MWCO) of 60,000 and 100,000, respectively, as well as hydrophobic polyvinylidene difluoride with MWCO of 100,000, were used under a constant flow rate and cross-flow mode in ultrafiltration of latex solution. In addition, a polycarbonate flat membrane with uniform pore size of 0.05 μm was likewise used during the experiment. The effects of CTAB on the latex particle size distribution were investigated at various concentrations, different treatment times, and diverse agitation duration times. The effects of CTAB on the zeta potential of membrane surfaces and latex particles were also investigated. The data obtained indicate that the particle size distribution of treated latex effluent experienced significant shifts in the peaks toward a larger size range caused by the aggregation of particles. As a result, the mass of fouling contributing to pore blocking and the irreversible fouling were noticeably reduced. The optimum results occurred in the instance when CTAB was added at the critical micelle concentration of 0.36 g/L, for the duration of 10 min and with minimal agitation. Notably, a higher stirring rate had an overall negative effect on the membrane fouling minimization.