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。     

Hunting Increases Dispersal Limitation in the Tree Carapa procera, a Nontimber Forest Product

Abstract:  The sustainability of seed extraction from natural populations has been questioned recently. Increased recruitment failure under intense seed harvesting suggests that seed extraction intensifies source limitation. Nevertheless, areas where more seeds are collected tend to also have more intense hunting of seed-dispersing animals. We studied whether such hunting, by limiting disperser activity, could cause quantitative dispersal limitation, especially for large crops and for crops in years of high seed abundance. In each of four Carapa procera (Meliaceae) populations in French Guiana and Surinam, two with hunting and two without, we compared seed fate for individual trees varying in crop size in years of high and low population-level seed abundance. Carapa seeds are a nontimber forest product and depend on dispersal by scatter-hoarding rodents for survival and seedling establishment. Hunting negatively affected the proportion of seeds dispersed and caused greater numbers of seeds to germinate or be infested by moths below parent trees, where they would likely die. Hunting of seed-dispersing animals disproportionally affected large seed crops, but we found no additional effect of population-level seed abundance on dispersal rates. Consistently lower rates of seed dispersal, especially for large seed crops, may translate to lower levels of seedling recruitment under hunting. Our results therefore suggest that the subsistence hunting that usually accompanies seed collection is at the cost of seed dispersal and may contribute to recruitment failure of these nontimber forest products. Seed extraction from natural populations may affect seedling recruitment less if accompanied by measures adequately incorporating and protecting seed dispersers.     

村级水资源的管理与利用研究--来自南方四个村的案例分析

农村水资源及其相关设施的改革需要更多了解村和户层次上的现实状况和机制安排。以避免改革扭曲和失败。通过对湖北和广西共四个村的村委会、关键知情人及120个农户的调查。在村和农户两个层次上描述水资源及其相关设施的管理与利用，尤其是在干旱年份村和户所采取的策略。并深入分析了农村村级水资源管理与利用的制度安排与问题。得出的结论是。追求水利管理效率的市场化改革需要考虑干旱的威胁，要有基于风险的制度设计和法律保障。     

新疆石化工业区颗粒物含水量和酸度对二次无机组分形成的影响

大气二次污染物是新疆独山子区大气污染物的重要组成部分,研究大气中二次组分的转化过程对区域大气污染治理有着重要意义.对新疆独山子区2015年9月至2016年7月采集到的样品进行水溶性组分分析.结果表明,水溶性无机离子(TWSIs)表现出与PM_(2.5)一致的季节变化,为冬季(67.86μg·m~(-3))秋季(13.77μg·m~(-3))春季(10.09μg·m~(-3))夏季(4.85μg·m~(-3));冬季二次无机离子(NH~+_4、SO~(2-)_4和NO~-_3)占TWSIs的98%;结合气溶胶热力学模型(E-AIM)探讨独山子区大气颗粒污染物中颗粒相含水量以及颗粒酸碱性;表明独山子区颗粒物呈酸性,年均原位pH为0.81,其中冬季样品的pH(2.93)值最高;颗粒含水季节变化为冬季(331.32μg·m~(-3))秋季(5.91μg·m~(-3))春季(5.46μg·m~(-3))夏季(1.62μg·m~(-3));年均氮氧化率(NOR)和硫氧化率(SOR)分别为0.13和0.47,表明区域污染物存在二次转化;进一步分析表明颗粒相中的硫酸盐质量浓度受到颗粒含水量和颗粒酸碱度的影响较为明显;高的颗粒相含水条件下区域硝酸盐的形成主要以非均相反应为主.     

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.     

联合改良剂对桉树吸收重金属的作用——以矿区土壤中Cd、Zn和Cu为例

通过5种矿区土壤的盆栽试验,研究了联合改良剂对桉树部分生理指标、根中Cd、Zn和Cu的含量、以及土壤中Cd、Zn和Cu的BCR提取形态的影响,探讨了其对矿区土壤还林的作用.结果表明,与对照相比,施用改良剂后桉树的生物量和叶绿素含量的增幅分别为-7.6%~158.8%和-0.7%~23.1%,丙二醛含量的降幅为2.6%~37.9%,其中部分处理的生物量和丙二醛含量的变化达到显著水平（P<0.05）;土壤中有效态Cd、Zn和Cu的含量分别下降12.5%~63.8%、1.6%~54.7%和16.2%~57.6%,桉树根中Cd、Zn和Cu的含量分别下降3.1%~56.6%、-1.5%~21.3%和9.3%~50.1%.土壤对桉树根中Cd、Zn和Cu的含量有显著影响（P<0.05）,改良剂的配比或施用量无显著影响（P>0.05）,但在5种矿区土壤中G3降低桉树根中Cu含量的效果优于G1和G2;在重金属含量最高的2种土壤中,G1降低桉树根中Cd和Zn含量的效果优于G2和G3.研究表明施用联合改良剂能降低桉树对重金属的吸收,有利于矿区土壤的还林.     

铝合金的实验室盐雾试验腐蚀行为图像特征提取

目的提取铝合金材料在盐雾箱试验中可以表征腐蚀程度的表面形貌图像特征量。方法首先,对采集于表面化学清洗过的试样原始图像进行图像增强等预处理,突出腐蚀部位;其次,基于数字图像处理的分形和小波分解方法提取出分形维数和小波能量特征值。结果与以质量损失量为基础的腐蚀深度特征值进行相关性对比,基于图像分析的特征提取法的准确度和精度比较高。结论该方法可以应用于对试样的腐蚀程度进行定性和定量分析,判断并预测试样的腐蚀速度。     

石墨炉原子吸收光谱法测定海河下游水中痕量镉

原子吸收光谱法直接测定高盐水中痕量镉时，有很大背景吸收和误差。本文采用络合—萃取技术使共存元素与待测元素分离，既消除了基体干扰，又达到了富集作用，使测定结果准确可靠。     

超临界二氧化碳萃取－GC／MS测定土壤中的多环芳烃

本文开发了一种采用超临界二氧化碳萃取土壤中多环芳烃、不须经过纯化步骤，直接可用于ＧＣ／ＭＳ分析的简便、高效的方法。本实验中超临界革取的流体是二氧化碳，改善剂是５％的二氯甲烷／甲醇，萃取温度为１２０℃、压力为３４ＭＰａ。ＧＣ／ＭＳ分析时除了采用外标外，还加入了６种同位素ＰＡＨｓ内标以校正各段ＰＡＨｓ的响应因子。采用本方法成功地测定了我国未开垦森林土壤中的ＰＡＨｓ。