Review: recent advances in biogas purifying technologies

Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques.     

可张孔曝气器曝气能耗试验研究

通过试验研究，总结出可张孔曝气阻力损失的影响因素，以优化产品的结构设计参数，降低产品在工程应用中的能耗，获取更好的经济效益。     

Fluctuations of Population Size and Structure in the Northern Mole Vole: Preliminary Analysis

Long-term stationary studies on the ecology of the northern mole vole (Ellobius talpinus Pall.), performed by the mark–recapture method from 1985 to 1997, have provided original data on population dynamics and structure. The analysis shows that, to reveal cyclic fluctuations of population size in this species, the period of three years should be taken as a unit of time for estimating the duration of one phase. The 12-year population cycle in E. talpinus has four distinct phases: an increase, a peak, a decline, and a minimum. At each phase, the population is characterized by certain features of family structure, age composition, birth and death rates, and the composition of migrants.     

碘化阶层孔氧化硅纳米球对水中典型有机氯污染物的吸附性能研究

采用共缩聚法,成功地原位合成了碘改性的阶层多孔氧化硅纳米球（SiO₂-I）,研究了其基于卤键作用对典型有机氯污染物六六六的吸附性能,并考察了改性剂I-硅烷含量和pH值对吸附效果的影响.实验结果表明,该纳米材料对六六六表现出优异的吸附富集性能,吸附速率快,60 min内对六六六的去除率为71.6%,240 min内达到吸附平衡,去除率可达98.3%,最大吸附量为178.6 mg·g^-1;吸附动力学符合拟二级动力学模型;碘物种的加入提高了阶层多孔氧化硅的吸附速率和吸附效率.另外,为了便于纳米吸附材料的分离,本研究对SiO₂-I纳米球进行了磁性化.研究发现,磁性化修饰后,SiO₂-I纳米材料仍然保留对六六六优异的吸附富集性能,240 min时的吸附去除率达90.3%.     

臭氧耦合陶瓷膜过滤对膜性能及出水消毒副产物的影响

利用臭氧（O₃）-陶瓷膜过滤（CMF）处理常规工艺出水,研究了不同O₃-CMF耦合方式对膜性能和消毒副产物（DBPs）的影响.结果表明,与单独CMF相比,异位O₃-CMF和原位O₃-CMF均可以有效缓解膜污染,原位O₃-CMF控制效果最佳.异位O₃-CMF对进水（常规工艺出水） DOC去除率（26.25%）略高于原位O₃-CMF（22.31%）,但是其SUVA去除率（83.91%）明显低于原位O₃-CMF（93.10%）.羟基自由基（·OH）生成特征表明原位O₃-CMF可促进O₃产生更多的·OH.在O₃、·OH氧化和陶瓷膜截留协同作用下,异位O₃-CMF和原位O₃-CMF出水中总荧光响应强度和相对分子质量大于0.3×10³,有机物含量降低,进而使得出水中含碳消毒副产物（C-DBPs）生成量分别降低了21.86%和32.35%,含氮消毒副产物（N-DBPs）生成量分别降低了16.16%和19.13%.但O₃和·OH氧化后生成的小分子有机物因难以被CM截留导致其在出水中含量增加,进而增加了卤代酮（HKs）、水合氯醛（CH）和三卤硝基甲烷（THNMs）的产生.本研究对于不同O₃-CMF方式下O₃与CM的协同机制的探讨,改善膜性能和提升DBPs前体物的去除具有一定指导意义.     

成都市大气颗粒物粒径分布及其对能见度的影响

使用环境颗粒物分析仪（GRIMM180）对成都市2018年10月—2019年9月0.25~32 μm的大气颗粒物数浓度粒径分布进行观测,结合细颗粒物（PM_2.5）质量浓度以及相对湿度（RH）、能见度、降水量等气象要素数据,分析了成都市大气颗粒物粒径分布及其与能见度的关系.结果表明,观测期间成都市大气颗粒物以细粒子为主,0.25~0.5 μm的粒子数浓度占总数浓度的97.75%,数浓度谱呈单峰分布,2018年秋季、2019年夏季表面积谱呈双峰分布,2018年冬季、2019年春季表面积谱呈三峰,体积谱均为三峰分布;在不同RH区间,PM_2.5质量浓度及数浓度均与能见度呈负相关,且其中0.25~0.5 μm粒径段的细颗粒物因为对可见光波段的米散射效应而对能见度产生较大影响;在不同RH情况下,不同粒径段颗粒物数浓度对能见度的影响程度有所差别：在低RH（<70%）下,0.25~0.3 μm粒径段粒子数浓度对能见度影响最大;在中等RH（70%~80%）下,0.3~0.5 μm粒径段粒子数浓度对能见度的影响最大;而在高RH（>80%）下,0.3~0.5 μm和0.5~1 μm粒径段粒子数浓度对能见度影响相当.     

雨水管道沉积物中典型无机氮的干期粒径分布

以南京江北新区分流制雨水管道沉积物为研究对象,考察不同粒径沉积物中铵态氮（NH₃-N）和硝态氮（NO₃^--N）干期分布特征,分析其随干期长度的变化关系,并探讨沉积物理化性质及微生物菌群结构对NH₃-N和NO₃^--N干期分布的影响.结果表明：粒径≤0.075mm的沉积物中NH₃-N占比最高（交通区30.8%,商业区36.7%）;交通区粒径≤0.075mm的沉积物中NO₃^--N占比最高（33.0%）,而商业区粒径0.075~0.15mm沉积物中NO₃^--N占比最高（34.4%）;干期长度与交通区0.075~0.15mm粒径段的沉积物中NO₃^--N含量及商业区粒径≥0.3mm的沉积物中NH₃-N含量之间的相关性均最显著;雨水管道沉积物中NH₃-N和NO₃^--N的干期分布与O-H和N-H等官能团、表面极性和亲水性、微观形貌等有一定关联;交通区雨水管道沉积物中Gemmobacter等反硝化优势菌种（相对丰度总和为20.15%）对NO₃^--N干期分布影响更显著.     

海绵城市地块汇水区颗粒污染物的传输

目前我国海绵工程建设多集中在地块汇水区单元内开展,通过多个低影响开发(LID)设施协同完成地表径流水质水量的调控,但基于地块汇水区尺度下城市面源污染的产生和控制效果鲜有报道.本研究比较分析了不同硬化率地块汇水单元内的面源颗粒污染物晴天累积、降雨冲刷、地表径流及径流输出负荷状况.结果表明,地块汇水单元内硬质路面是面源颗粒污染物贡献的最主要的下垫面类型,中硬化率(61.1%)地块和高硬化率(73.6%)地块路面街尘累积量分别约占汇水区单元的88.4%(2.22～12.51 g·m~(-2))和90.1%(4.99～33.43 g·m~(-2)),对径流SS的输出贡献比率分别约为91.7%(0.97～7.34 g·m~(-2))和90.5%(0.92～18.77 g·m~(-2)),降雨径流SS污染负荷占比分别约为95.2%和83.1%,经LID设施处理后输出径流污染负荷约为地表径流的24.0%和40.2%.硬质路面的街尘晴天累积及降雨冲刷以150μm为主,地表径流及输出径流则以50μm粒径段为主,同时地块不透水比例的增加,细粒径(105μm)颗粒物的累积及冲刷分布增大(24.4%和106.4%),而粒径50μm的颗粒物在路面径流中的分布减小(12.4%).屋面的街尘累积、冲刷及降雨径流的粒径分布状况与硬质路面大致相似,但中硬化率地块(1 000μm)和高硬化率地块(250～450μm、45μm)在3个粒径段范围的颗粒物累积和冲刷相较于路面街尘粒径分布明显增加(1 000μm:58.1%和108.5%; 250～450μm:72.9%和41.8%;45μm:59.2%和64.8%).以上结果揭示了颗粒污染物在地块汇水区尺度下的污染全过程(累积-冲刷-输出)分布及LID设施对地块整体SS污染负荷的控制效果,可为地块汇水单元内LID设施工程绩效的科学评估提供重要参考.     

Determination of organophosphorus pesticides and related compounds in water samples by membrane extraction and gas chromatography

A membrane extraction-gas chromatography method was developed fordetermination of organophosphorus pesticides and related compounds including methamidophos, DDVP, dimethoate, methyl parathion, parathion, thiophosphoric acid trimethyl ester, and thiophosphoramidic acid dimethyl ester in water samples. In thismethod, surface-modified acetic cellulose membranes were used to extract the target analytes in water samples, the extracted analytes were back-extracted into a small amount of methanol, andgas chromatography with pulsed flame photometric detector (GC-PFPD) was used to determine the concentrations of targetanalytes in the extracts. The recoveries obtained for thetarget analytes spiked into the water samples ranged from 66to 94%. The method detection limit for each target analyte was 0.05 g L^-1. The method developed in this study had shown the advantages of being cheap, simple, fast, and reliable. It had been used successfully to determine the concentrations of target analytes in river water samples.     

Large pore size polyacrylonitrile membrane for ultrafiltration

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