Optimized photocatalytic regeneration of adsorption-photocatalysis bifunctional composite saturated with Methyl Orange

Photo-responsive adsorption-photocatalysis nanocomposites are generally used in water and wastewater decontamination; however, the prolonged adsorption capacity of composites and the role of adsorption in concomitant photocatalysis are typically neglected. These composites can be regenerated under light irradiation as their adsorption capacity decreases. Herein, a novel adsorption-photocatalysis bifunctional nanocomposite, Bi-doped TiO₂ supported on powdered activated carbon (Bi₂O₃/TiO₂/PAC), was prepared using the sol-impregnation-hydrothermal procedure. Bi₂O₃/TiO₂/PAC with a secondary calcination temperature of 700°C under a nitrogen atmosphere was selected for maximum adsorption capacity on Methyl Orange (MO). The composite displayed an excellent adsorption capacity and was easily separated and recycled. The results demonstrate that 71.2% photocatalytic regeneration efficiency could be attained under visible light irradiation for 1 hr at an intensity of 750?W/m² and pH 7. Characterization of the as-prepared Bi₂O₃/TiO₂/PAC nanocomposite (700°C) indicates that it possesses a highly specific surface area and great optical properties, showing bifunctional adsorption-photocatalysis characteristics. The p-n heterojunction of the composite played a dominant role in the photocatalytic regeneration process, and effective degradation of MO could be achieved along with composite regeneration.     

Adsorption mechanisms of PFOA onto activated carbon anchored with quaternary ammonium/epoxide-forming compounds: A combination of experiment and model studies

When wood-based activated carbon was tailored with quaternary ammonium/epoxide (QAE) forming compounds (QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid (PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before half-breakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.     

我国农村生活污水污染排放及环境治理效率

当前我国农村生活污水治理形势依然严峻.利用第二次全国污染源普查成果,分析了我国2017年农村生活污水排放情况,并基于熵值法和数据包络分析（DEA）模型从技术效率、经济效率两个角度对治理效率进行评价.结果表明:①我国农村生活污水中COD排放量约占生活源排放总量的50.8%,NH₃-N、TN和TP排放量分别占生活源排放总量的35.0%、30.5%、38.7%,污水及污染物排放去向以直排入水体、直排入农田和其他途径为主,三者占80%以上.②我国沿海用水量较大地区的水冲式厕所比例超过80%,且农村生活污水有效治理比例仅为11.0%,导致我国农村生活污水治理的技术效率仅为8.6%,且区域差异较大,其中有23个省份小于10%,技术效率普遍较低.③相比浙江省、上海市、山西省、内蒙古自治区、青海省、西藏自治区等地（经济效率均为1）,我国其他省份农村生活污水治理的经济效率有很大改善空间.农村生活污水中人均COD排放强度、人均NH₃-N排放强度与农村居民人均可支配收入之间的环境库兹涅茨曲线（EKC）均呈一定的倒“U”型关系,人均TN排放强度、人均TP排放强度与农村居民人均可支配收入之间的EKC则均呈“N”型特征,有波动上升趋势.研究显示,我国农村生活污水治理效率存在较大的提升空间,与城镇相比,农村的环境保护基础设施建设还比较落后,应以源头减量、分类处理、循环利用为导向,加强统筹规划,梯次推进,加快提升我国农村污水治理水平.      

部分亚硝化-厌氧氨氧化处理磁混凝生活污水

以磁混凝预处理后的生活污水为处理对象,构建了部分亚硝化-厌氧氨氧化分体式反应器,通过曝气调控与生物强化促进部分亚硝化反应的稳定进行,并耦合厌氧氨氧化反应进行深度脱氮.近100d的运行结果表明,在生物强化和间歇曝气的控制条件下,亚硝酸盐积累率达到了89.93%;提高亚硝化反应器中曝气阶段溶解氧浓度（从0.6~0.8mg/L升高至1.0~1.2mg/L）有利于氨氮与总氮去除.该系统最高能够去除95.45%的氨氮和86.28%的总氮,实现了稳定、高效脱氮;磁混凝预处理后的生活污水在亚硝化反应器中,间歇曝气条件促进了残留的溶解性有机物为反硝化提供碳源,COD总去除率达到64.65%~74.42%,并且亚硝化反应器出水与系统最终出水的有机物组分相似,主要为难降解有机物.     

基于配额指标重要性视角的中国碳排放配额再分配

提出用与碳排放“同步变化程度”来衡量配额指标重要性的思想,对中国各省份碳排放配额进行再分配.首先在公平和效率原则基础上选取碳排放的影响因素作为分配指标,其次采用灰色关联分析法分别测算出各地区各指标与碳排放量的同步变动程度,以得到各地区各指标在配额分配中的比重.最后测算出我国29个省区2020~2030年的碳排放配额与排放空间.结果表明,人口基数及经济发展指标对各地碳排放有较强的同步变动关联性,因此应该被赋予更高的权重;配额最多的地区包括广东、北京、江苏、山东、上海,最少的地区则包括宁夏、贵州、青海、吉林、新疆.盈余分析发现,北京地区的碳排放空间有较多盈余;浙江等5个省区已达较饱和状态;山东等4个省区则处于较严重的溢出状态,在未来10年内需承担较重的减排压力.     

Assessment of sunflower germplasm for phytoremediation of lead-polluted soil and production of seed oil and seed meal for human and animal consumption

Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands, but phytoremediation without economic revenue is unfeasible for land owners and farmers. The use of crops with high biomass and bioenergy for phytoremediation is a unique strategy to derive supplementary benefits along with remediation activities. Sunflower (Helianthus annuus L.) is a high-biomass crop that can be used for the phytoremediation of polluted lands with additional advantages (biomass and oil). In this study, 40 germplasms of sunflower were screened in field conditions for phytoremediation with the possibility for oil and meal production. The study was carried out to the physiological maturity stage. All studied germplasms mopped up substantial concentrations of Pb, with maximum amounts in shoot?>?root?>?seed respectively. The phytoextraction efficiency of the germplasm was assessed in terms of the Transfer factor (TF), Metal removal efficiency (MRE) and Metal extraction ratio (MER). Among all assessed criteria, GP.8585 was found to be most appropriate for restoring moderately Pb-contaminated soil accompanied with providing high biomass and high yield production. The Pb content in the oil of GP.8585 was below the Food safety standard of China, with 59.5% oleic acid and 32.1% linoleic acid. Moreover, amino acid analysis in meal illustrated significant differences among essential and non-essential amino acids. Glutamic acid was found in the highest percentage (22.4%), whereas cysteine in the lowest percentage (1.3%). Therefore, its efficient phytoextraction ability and good quality edible oil and meal production makes GP.8585 the most convenient sunflower germplasm for phytoremediation of moderately Pb-contaminated soil, with fringe benefits to farmers and landowners.     

旋翼结冰对直升机悬停性能影响的数值分析

目的 研究旋翼结冰对直升机悬停性能的影响。方法 选取具有充分试验数据的UH-1H直升机为算例,采用Fluent计算旋翼流场,将收敛后的流场文件导入Fensap-ICE中进行水滴撞击和结冰计算,得到结冰后的旋翼外形后,再采用Fluent计算旋翼流场,从而分析旋翼结冰对直升机悬停性能的影响。结果 通过改变结冰条件,分析了不同结冰条件对直升机悬停效率的影响,表明旋翼结冰会显著降低直升机的悬停效率,且随着结冰时间、水滴平均直径(MVD)和液态水含量(LWC)的增大,直升机的悬停效率逐渐降低。结论 不同结冰条件对直升机悬停效率下降趋势的影响不同,随着结冰时间的增大,悬停效率基本呈线性下降,而随着MVD和LWC的增大,悬停效率的下降趋势逐渐变缓,下降幅度逐渐减小。     

基于能值分析的西安市三个发展核心区可持续性研究

本文基于能值分析和城市复合生态系统的理论与方法,从生态环境系统及社会经济系统两方面,对西安市灞桥区、雁塔区和未央区2014年的基础数据进行计算整理,通过分析三个发展核心区的能值利用效率,排除废物流能值对系统的消极影响,构建基于能值利用效率(EUE)的系统可持续发展程度指标(EUSDI),确切评估三个区城市复合生态系统的可持续发展能力。结果表明:灞桥区可持续发展指数为0.1545,雁塔区为0.0906,未央区为0.0579。灞桥区能值利用效率为较高的94.81%,可更新资源较为丰富,但较为依赖不可更新资源与外部输入产品;雁塔区能值利用效率为较低的86.57%,社会经济发展程度较高,但可更新资源较贫乏,人口过于集中对环境造成很大压力;未央区能值利用率为较低的84.93%,该区可更新资源较少,工业生产消耗大量不可更新资源,"三废"的排放也严重影响了该区的生态环境。     

直流电场强化活性污泥法处理木质素废水的效能、污泥特性及群落结构研究

以溶解态木质素模拟废水为研究对象,考察了不同直流电场条件下活性污泥反应器(R1,无电流,悬浮污泥)、电极生物膜反应器(R2,电流I=10~60 mA,无悬浮污泥)与电极生物膜-活性污泥反应器(R3,I=10~60 mA,悬浮污泥)中木质素废水的处理效能、污泥生理特性(活菌比、木质素过氧化物酶(LiP)、三磷酸腺苷(ATP)等)、细胞膜磷脂脂肪酸组成及微生物群落结构的差异.结果表明:相同的外加电流下,R3的木质素去除率均高于R2(p0.05),其中,30 mA时达到最大值30.19%±0.47%,分别为R1、R2木质素去除率的2.01倍和1.46倍.反应器R2在20~40 mA时的总氮去除效果最好,达到71.96%±5.79%.分析R1、R3悬浮污泥发现,外加电流升高不改变悬浮污泥的活菌比(p0.05),木质素去除率受LiP酶活影响不大;与低电流(10~30 mA)相比,高电流(40~60 mA)下悬浮污泥中C15∶0 ANTEISO的含量降低,长链磷脂脂肪酸(C19、C20)的相对含量增加;R3悬浮污泥中Flavobacterium、Pseudomonas和Janthinobacterium等可降解木质素的菌属在10 mA外加电流的刺激下相对丰度均最高.在电极微生物方面,与R3相比,R2阴极微生物中具有反硝化能力的Methyloversatilis成为优势菌属,阳极微生物中存在更多具有电子传递能力的菌属(Pseudomonas、Ralstonia).冗余分析(RDA)表明,悬浮污泥中Mycobacterium(降解木质素的好氧细菌)丰度与电流(I)显著正相关(p0.05),与不饱和脂肪酸(UFA)显著负相关(p0.05).