Dust collection efficiency analysis in a two-dimensional circulating granular bed filter

Dust collection efficiency data were analyzed to determine better operating conditions for a two-dimensional circulating granular bed filter (CGBF). The dust collection efficiency in the granular bed was affected by the following operating parameters: the louver angle, the solids mass flow rate, and the particle size of the bed material. Experimental results showed that higher dust collection efficiency occurs when the solids mass flow rates were 20.34 +/- 0.24, 21.50 +/- 0.11, and 30.51 +/- 0.57 g/sec at louver angles of 45 degrees, 30 degrees, and 20 degrees, respectively. Optimal dust collection efficiency peaked with a louver angle of 30 degrees. Average particle sizes of bed material by sieve diameters (microm) of 795 microm had higher dust collection efficiency than the average collector particle size of 1500 microm. Dust collection efficiency is influenced by bed material attrition phenomenon, causing dust collection efficiency to decrease rapidly. The dust collection efficiency analysis not only found the system free of design defects but also assisted in the operation of the two-dimensional CGBF system.     

机械故障振动信号征兆提取方法

在机械状态监测与故障诊断中，故障征兆的提取是关键环节，本文将介绍几种效果较好的故障征兆提取方法。     

电选法回收利用废印刷线路板

废印刷线路板含有多种有价值的物质，随意丢弃或处理处置方法不当既污染环境，又造成资源流失。采用剪切式破碎和电力分选技术对废印刷线路板的机械分离进行了研究。结果表明，电选法可以实现废印刷线路板中金属和玻璃纤维、树脂的分离；在实验的粒径范围内（-14＋20目到-120＋200目分为5个粒径级别），金属主要集中在-20＋120目粒级范围内，且该粒级范围分选效果最好。     

分光光度法测定降水中微量过氧化氢

研究了一种测定降水中微量过氧化氢的方法。在0.4～1.5mol／L磷酸介质中，过氧化氢与钒（V）及2－（3，5-二溴-2-吡啶偶氮）－5-二乙氨基苯酚（3,5-diBr-PADAP）反应形成一种组成比为1：1：1的蓝色三元配合物，其最大吸收波长为598nm，表现摩尔吸光系数为5.6×104L·mol-1·cm-1。过氧化氮量在2×10-7～1．3×10－5mol／L时服从比耳定律。方法简便，选择性较高，用于降水中微量过氧化氢的直接测定，结果令人满意。     

A simple effective procedure for the determination of adenosine triphosphate in soils

A simple method for the extraction and determination of adenosine 5′-triphosphate (ATP) in soil is described. ATP was extracted by stirring with dimethyl sulphoxide (DMSO), followed by adding 0.01 M trisodium phosphate (Na₃PO₄) buffer solution for a further dispersion. The ATP content was quantitatively measured by luciferin-luciferase system employing a standard addition technique. The method was most efficient in comparison with 7 other extraction procedures. The recoveries of ATP in spiked soil were found to be approximately 100 %. ATP contents in 16 selected soils were in ranges of 0.76±0.05 – 7.79±0.83 μg/g (dry weight). A significant correlation between ATP amounts and biomasses in these soils was also observed.     

纳米TiO2光催化降解酸性粒子元青溶液的研究

对纳米 Ti O2 光催化氧化法降解酸性粒子元青溶液进行了试验研究。结果表明 ,反应符合一级反应 ,反应速率常数为2 .9× 10 - 3min- 1。确立的最佳工艺条件 :催化剂的用量为 4.0 g·L- 1 ,溶液的 p H为 6.3 8,空气的体积流量为 12 0 m L· min- 1 ,在此最佳工艺条件下 ,酸性粒子元青的降解率达到 92 .3 %。且测得反应的表现活化能 Ea为 -17.9k J· mol- 1 。     

影响病毒在物体表面和空气中生存的因素分析

新型冠状病毒肺炎（COVID-19）疫情严重危害人类生命安全和影响国家经济发展.截至目前,关于环境条件（湿度与温度）、空气污染及人为活动对2019-nCoV传播的文献鲜见报道.由于新型冠状病毒（2019-nCoV）采样困难,难以开展直接试验研究,因此通过对国内外其他类似病毒文献调研,探究影响病毒传播和生存的影响因素,以期为疫情防控和控制2019-nCoV传播提供指导.结果表明:①冠状病毒在低温低湿的环境中能够保持较长的存活时间与传播力,尤其在干燥物体表面停留时间更长,如冠状病毒能在温度为22~25℃、相对湿度（RH）为40%~45%的光滑物体表面存活5 d以上;②同时,冠状病毒气溶胶在低温低湿的条件下也具有高存活率,提示在密闭环境中2019-nCoV气溶胶可能在温度为20~25℃、相对湿度为30%~50%的条件下具有较高的存活率;③颗粒物浓度越高,2019-nCoV传播的风险可能随之增加;④感染者的行为活动也对2019-nCoV的传播起着不可忽视的作用,应避免在人群中打喷嚏、咳嗽,并且用手、手肘或其他物品加以防护,降低病毒传播的可能性.综上,提出几点疫情防控的相关建议,如改善室内微环境和开展2019-nCoV的检测、灭活、影响因素、传播规律等相关研究工作.      

Effective removal of antibiotic resistance genes and potential links with archaeal communities during vacuum-type composting and positive-pressure composting

As a major reservoir of antibiotics, animal manure contributes a lot to the augmented environmental pressure of antibiotic resistance genes (ARGs). This might be the first study to explore the effects of different ventilation types on the control of ARGs and to identify the relationships between archaeal communities and ARGs during the composting of dairy manure. Several ARGs were quantified via Real-time qPCR and microbial communities including bacteria and archaea were analyzed by High-throughput sequencing during vacuum-type composting (VTC) and positive-pressure composting (PPC). The total detected ARGs and class I integrase gene (intI1) under VTC were significantly lower than that under PPC during each stage of the composting (p < 0.001). The relative abundance of potential human pathogenic bacteria (HPB) which were identified based on sequencing information and correlation analysis decreased by 74.6% and 91.4% at the end of PPC and VTC, respectively. The composition of archaeal communities indicated that methane-producing archaea including Methanobrevibacter, Methanocorpusculum and Methanosphaera were dominant throughout the composting. Redundancy analysis suggested that Methanobrevibacter and Methanocorpusculum were positively correlated with all of the detected ARGs. Network analysis determined that the possible hosts of ARGs were different under VTC and PPC, and provided new sights about potential links between archaea and ARGs. Our results showed better performance of VTC in reducing ARGs and potential HPB and demonstrated that some archaea could also be influential hosts of ARGs, and caution the risks of archaea carrying ARGs.     

Effects of Al3+ on the microstructure and bioflocculation of anoxic sludge

The aluminum ions generated from mining aluminum,electrolytic aluminum and the industrial production of aluminum-based coagulants(such as AlCl_3 and Al_2(SO_4)_3) enter sewage treatment plants and interact with activated sludges.An anaerobic/anoxic/oxic(A~2 O) process was used to reveal the effects of Al~(3+) on the pollutant removal efficiencies,bioflocculation and the micro structure of sludge.The results showed that a low concentration of Al~(3+) improved the pollutant removal efficiencies and increased the sludge particle size.However,a high concentration of Al~(3+) hindered microbial flocculation and reduced the pollutant removal efficiencies.With a 10 mg/L Al~(3+) addition,the chemical oxygen demand(COD),total nitrogen(TN) and NH_4~+-N increased by 3%,16% and 27%,and reached as high as 68%,60% and 87%,respectively.At the same time,the dehydrogenase activity,flocculation ability(FA) and contact angle of the sludge reached their maximum levels at 41.3 mg/L/hr,45% and 79.63°,respectively.The specific surface area of the sludge decreased to 7.084 m2/g and the sludge pore size distribution shifted to concentrate in the me soporous range.Most of Al~(3+) was adsorbed on the surface of sludge,changing the physicochemical properties and physical structure of the sludge.     

The effects of hydrogen peroxide pre-oxidation on ultrafiltration membrane biofouling alleviation in drinking water treatment

Pre-oxidation is widely used to reduce ultrafiltration membrane fouling.However,the variation in the composition of microbial communities and extracellular polymeric substances(EPSs) accompanying pre-oxidation in drinking water treatment has received little attention.In this study,hydrogen peroxide(H_2O_2) was used in a coagulationultrafiltration process with Al_2(SO_4)_3·18H_2O.A long-term reactor experiment(60 d) showed that pre-oxidation alleviated membrane fouling,mainly due to its inhibition of microbial growth,as observed by flow cytometry measurements of the membrane tank water.Further analysis of the formed cake layer demonstrated that the corresponding levels of EPS released from the microbes were lower with than without H_2O_2 treatment.In comparison to polysaccharides,proteins dominated the EPS.2 D-electrophoresis showed little difference(p 0.05,Student's t-test) in the composition of proteins in the cake layer between the treatments with and without H_2O_2.The molecular weights of proteins ranged from approximately 30–50 kDa and the majority of isoelectric points ranged from 6 to 8.Highthroughput sequencing showed that the predominant bacteria were Proteobacteria,Bacteroidetes,and Verrucomicrobia in both cake layers.However,the relative abundance of Planctomycetes was higher in the cake layer with H_2O_2 pre-oxidation,which was likely probably due to the strong oxidative resistance of its cell wall.Overall,our findings clarify the fundamental molecular mechanism in H_2O_2 pre-oxidation for ultrafiltration membrane bio-fouling alleviation in drinking water treatment.