Understanding the granulation process of activated sludge in a biological phosphorus removal sequencing batch reactor

The granulation of activated sludge was investigated using two parallel sequencing batch reactors (SBRs) operated in biological nitrogen and phosphorus removal conditions though the reactor configuration and operating parameters did not favor the granulation. Granules were not observed when the SBR was operated in biological nitrogen removal period for 30 d. However, aerobic granules were formed naturally without the increase of aeration intensity when enhanced biological phosphorus removal (EBPR) was achieved. It can be detected that plenty of positive charged particles were formed with the release of phosphorus during the anaerobic period of EBPR. The size of the particles was about 5-20 μm and their highest positive ζ potential was about 73 mV. These positive charged particles can stimulate the granulation. Based on the experimental results, a hypothesis was proposed to interpret the granulation process of activated sludge in the EBPR process in SBR. Dense and compact subgranules were formed stimulated by the positive charged particles. The subgranules grew gradually by collision, adhesion and attached growth of bacteria. Finally, the extrusion and shear of hydrodynamic shear force would help the maturation of granules. Aerobic granular SBR showed excellent biological phosphorus removal ability. The average phosphorus removal efficiency was over 95% and the phosphorus in the effluent was below 0.50 mg L⁻¹ during the operation.     

Energy conversion from electrolyte concentration gradient using charged nano-pores

Power generation based on the reversed electro-dialysis (RED) cell is studied both numerically and experimentally in this work. The membrane that separates the concentrated and dilute electrolytes is treated as a charged nano-pore array. Both numerical and experimental results show that the RED cell performance is similar to the typical electrochemical cell having a linearly varied current–voltage relation. The open circuit voltage and short-circuit current depend on the ion selectivity of the nano-pore membrane, which is related to the concentration ratio, pore surface charge density, and pore size. The highest energy conversion efficiencies are approximately 48% and 24% from numerical predictions and experimental measurements, respectively. The reason for this discrepancy is attributed to the inhomogenous pore size and surface charge density distributions of the Al₂O₃ membrane used in these experiments.     

水雾荷电振弦纤维栅除尘器除尘性能影响因素的实验研究

为研究除尘系统结构最优配置,实验采用新型高效水雾荷电振弦栅除尘方法,以除尘效率及阻力损失为参照结果,选定纤维栅板数量、纤维栅与喷嘴间距、纤维栅材料和间隙4个因素进行单因素试验,针对各因素对纤维栅除尘效率的影响进行了分析研究,结果表明多块纤维栅除尘效果明显优于单块纤维栅,正常处理风速时3块纤维栅的除尘效率最高,纤维栅阻力与其数量呈正比;纤维栅除尘效率随间距增大而先增后减,间距为230 mm时除尘效率最高;塑胶纤维栅除尘效果明显优于其他材料,各阻力值排序为:塑胶＞涤纶＞不锈钢＞尼龙;纤维栅除尘效率随纤维间隙增大而降低,其阻力随间隙增大而减小;利用SPSS软件进行4因素三水平正交试验分析,在特定条件下除尘效率显著性排序为:纤维栅数=纤维栅间隙＞纤维材料＞纤维栅与喷嘴间距;阻力损失显著性排序为:纤维栅数=纤维栅间隙=纤维材料=纤维栅与喷嘴间距;试验最佳配置为3块间隙0.6 mm尼龙纤维栅板,且纤维栅板距喷嘴最小间距为185 mm。     

论饮食业油烟治理技术的发展及应用

实际应用的饮食业油烟净化设备（以下简称油烟净化设备）中，以静电式、机械过滤式、湿式，以及由上述三种技术组成的复合式产品为主。荷电湿式油烟净化器的开发应用，将具有很强的市场竞争力，未来几年，静电式技术将继续被广泛采用，机械式技术将更多地作为预处理手段与其他技术组合使用，湿法技术因兼有部分除味和去除柴油灶燃烧颗粒的功能等特点将更有针对性地应用于适当的场所。优化组合而成的经济高效的复合式技术在未来市场中将占据主导地位。     

Characteristics and potential human health hazards of charged aerosols generated by high-voltage power lines

We investigated the characteristics of charged aerosols produced by high-voltage power lines (HVPLs) to explore the effects on respiratory disease incidence among those who handle HVPLs. Charged aerosol currents and charged aerosol concentrations were measured over 24?h at 12 sites. Aerosol current effective levels were 2.7 times higher compared to exposed and control sites. This pattern of relative enhancement at exposed sites was seen consistently in all measurements and the difference was 1.7 higher at exposed sites. Correlation analysis among all important variables revealed strong positive correlations between currents and concentration, currents and magnetic field, humidity and concentration, and humidity and particles of 10?µm or less (PM₁₀), while negative correlations were observed between charged aerosol concentrations and wind velocity and between wind velocity and humidity. Estimated production of charged aerosols from HVPLs found that people who work with HVPLs are highly likely to be exposed to charged aerosols.     

放电极性对多段冲击式静电除尘器收尘效率的影响

基于对不同极性荷电时多段冲击式静电除尘器的模型实验研究,发现双极交替荷电时该种除尘器比任何单极荷电具有更高的除尘效率。     

PI纤维在空间带电粒子辐照下的力学性能损伤

目的研究聚酰亚胺(PI)纤维在电子辐照、质子辐照、应力耦合质子辐照条件下力学性能的损伤行为。方法采用中国科学院长春应用化学研究所自主合成并纺丝制备的聚酰亚胺纤维,在空间环境模拟设备辐照的条件下,研究空间带电粒子对聚酰亚胺纤维辐照后的力学损伤行为,并通过XQ-1型纤维强度仪对辐照前后的样品进行拉伸试验。结果在低能电子辐照条件下,聚酰亚胺纤维的拉伸强度、模量和断裂伸长率均有所降低,但变化不太显著;高能电子辐照会提高材料的模量;质子辐照后,材料的拉伸强度和断裂伸长率随着辐照注量的增加明显降低;单一施加5%的应变会使聚酰亚胺纤维的拉伸力学性能有一定量下降。与单一应变样品相比,应力耦合质子辐照样品的拉伸强度和断裂伸长率进一步下降,但是与单一质子辐照样品相比,应力耦合辐照样品的拉伸强度和断裂伸长率都更高。结论无论是在低能电子辐照条件下,还是在高能电子辐照条件下,电子辐照对聚酰亚胺纤维力学性能影响均较微弱,而质子辐照会较大程度地降低材料的力学性能,增加应力耦合效应之后,质子辐照对材料的力学性能影响减弱。     

荷电超滤膜去除水中天然有机物的研究进展

较传统的超滤过程,使用荷电膜的超滤技术能实现对水中天然有机物(NOM)更高的去除率,并同时减少膜污染。文章从膜材料性质、溶液环境和NOM性质这几方面来综述荷电超滤膜去除水中天然有机物的研究进展。最后对荷电超滤膜去除NOM方面的进一步研究工作提出了建议。     

Advanced techniques in air pollution†

Specific usage of neutron activation analysis, charged particle analysis, y photons analysis, G.C.M.S. coupling, stable isotope dilution techniques, are discussed.

Dust collected on filters, oxygenated compounds in exhaust gases from car engines, nitrogen oxides, have thus been determined.

Special calibration methods for ozone, and remote detection by Lidar Raman are also described.     

水环境中腐殖酸的荷电特性与聚集特性

通过腐殖酸的Zeta电位和粒径的变化规律研究,探讨化学条件对腐殖酸的荷电状态和聚集状态的影响。结果表明,腐殖酸具有自我凝聚的特性;在pH较低和溶液离子强度较高时,腐殖酸胶粒的Zeta电位绝对值减小而聚合度增大,从而使腐殖酸胶粒聚集而凝聚;随腐殖酸浓度增大,腐殖酸胶粒的Zeta电位绝对值增大,腐殖酸胶粒的缩聚程度降低而使粒径减小。