Performance and mechanism of Cr(VI) removal by zero-valent iron loaded onto expanded graphite

Zero-valent iron (ZVI) was loaded on expanded graphite (EG) to produce a composite material (EG-ZVI) for efficient removal of hexavalent chromium (Cr(VI)). EG and EG-ZVI were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller (BET) analysis. EG-ZVI had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr(VI) removal performance. The results showed that the Cr(VI) removal rate was 98.80% for EG-ZVI, which was higher than that for both EG (10.00%) and ZVI (29.80%). Furthermore, the removal rate of Cr(VI) by EG-ZVI showed little dependence on solution pH within a pH range of 1–9. Even at pH 11, a Cr(VI) removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZVI could enhance the removal of Cr(VI) via chemical reduction and physical adsorption, respectively. X-ray photoelectron spectroscopy (XPS) was used to analyze the mechanisms of Cr(VI) removal, which indicated that the ZVI loaded on the surface was oxidized, and the removed Cr(VI) was immobilized via the formation of Cr(III) hydroxide and Cr(III)–Fe(III) hydroxide/oxyhydroxide on the surface of EG-ZVI.     

Ca~(2+)在好氧颗粒污泥形成中的作用

通过运行序批式生物反应器与摇瓶实验相结合方法,在进水中投加不同数量Ca2+(0～200mg/L),考察了Ca2+在好氧颗粒污泥形成中的作用.当SBRⅠ、Ⅱ进水Ca2+含量分别为30、100mg/L,运行20d后,两反应器中均出现了好氧颗粒污泥.运行前50d,SBRⅠ中颗粒污泥浓度MLSS与污泥沉降指数SVI指标明显好于SBRⅡ;运行80d后,SBRⅠ、Ⅱ中污泥浓度MLSS均稳定在7.5g/L,SVI分别为46～48mL/g、45～47mL/g,差异很小.反应器运行90d后,SBRⅠ、Ⅱ中污泥Zeta(ζ)电位为-12.5～-12.6mV;摇瓶实验中,当进水Ca2+为0～200mg/L,运行至60d时,摇瓶中污泥Zeta电位为-14.1～-14.4mV;进水中Ca2+含量的增加对污泥Zeta电位影响很小,没有引起好氧颗粒污泥Zeta电位的明显差异,电中和在颗粒污泥形成过程中并不起重要作用.随着进水Ca2+浓度增加,颗粒污泥中的微生物数量与种类都逐渐丰富,Ca2+有助于促进污泥中微生物多样性.接种污泥及SBR中颗粒污泥的元素含量分析表明,好氧颗粒污泥Ⅰ、Ⅱ与接种污泥相比,颗粒污泥中Ca、Mg、K、Na含量均有所减少,Fe含量分别增加了4.42%、7.82%.具有良好絮凝作用的金属离子与EPS间形成的高分子生物聚合体可能是促进好氧颗粒污泥形成的主要原因.反应器运行期间,SBRⅡ对污染物的去除性能始终高于SBRⅠ,运行70d后,SBRⅠ、Ⅱ中颗粒污泥对NH4+、COD去除率较高达到90%以上,对TN、TP的去除率为65%～70%.     

基于实例的系统聚类分析法在环境空气质量评价中的应用

基于系统聚类分析理论,介绍系统聚类最短距离法在环境空气质量评价中的应用。系统考虑影响环境空气质量的各种因素,在数据标准化处理的基础上,通过距离计算,达到对环境空气质量的系统分类,为制定区域环境综合治理措施和环境规划提供科学依据。     

宁波南沙港网箱养殖水域营养状况评价及生物修复策略

根据2007年1月-2007年11月4个航次对宁波南沙港网箱养殖水域水体营养盐（NO2--N、NO3--N、NH 4＋-N和PO34--P）含量的监测结果,利用营养指数E法对水体的富营养化状态进行了评价。根据网箱养殖系统物质平衡方程和现场调查实验数据,估算了南沙港网箱养殖水域的氮磷污染负荷,以溶解态氮作为平衡指标,估算了鱼藻类合理的配比模式。结果表明,南沙港水体中NO2--N、NO3--N、NH4＋-N、PO4-P含量年变化范围分别为0.26μmol/L～4.86μmol/L,33.93μmol/L～82.86μmol/L,0.59μmol/L～7.86μmol/L,1.47μmol/L～2.97μmol/L,不同养殖区之间营养盐含量差异不显著（p〈0.05）;营养指数E值年变化范围介于2.41～15.99之间,表明该港水体处于重度富营养化状态;养殖区N/P值的年平均值为32.95,表明南沙港海区是一个氮过剩的养殖系统。南沙港网箱养殖水域氮、磷的负荷量分别为70.43 t/a和5.96 t/a,其中溶解态氮、磷负荷量分别为49.3 t/a和2.38 t/a;南沙港的藻类养殖面积需要在现有基础上再扩大0.44倍,达到107.52 ha,才可以与网箱养殖系统的氮磷污染负荷构成平衡;网箱养殖个数与藻类养殖面积（ha）的合理配比约为1∶0.027。     

地质构造对地质灾害的影响研究——以鲁甸县强烈构造变形区为例

通过近一年的野外地质调查、室内资料整理、GIS综合信息模型分析等方法,总结归纳出鲁甸县各类地质灾害的分布特征,并分析阐述了其形成条件和机理,发现地质构造对灾害的分布和形成及易发性有重大影响。     

污泥对樟子松生物量及其重金属积累和土壤重金属有效性的影响

采用盆栽试验研究了不同剂量污泥(体积分数,即污泥体积占污泥和沙土总体积的百分比,分别为:0、20%、33.3%、50%和100%)施用于风沙土条件下,污泥剂量对樟子松幼苗生物量及其对重金属的累积和土壤中重金属有效性的影响.结果表明,在养分含量低的风沙土中,施用污泥能够显著提高樟子松幼苗生物量,最适剂量为50%;污泥剂量的增加可促进樟子松植株对重金属的吸收和累积,在最适剂量(50%)条件下,樟子松植株中Cu、Cd、Pb、Zn的累积量分别是对照(不施污泥)的18.0、8.9、17.1、11.5倍;樟子松植株重金属吸收速率顺序为:ZnCuPbCd,而迁移系数顺序为:ZnCdCuPb;土壤中有效态重金属含量随污泥剂量的增加而增加,而植株收获后土壤中有效态重金属下降幅度均小于对照.     

低温时污泥膨胀对MBR中膜污染的影响

通过一体式膜生物反应装置考察了在低温条件下发生污泥膨胀过程中反应器的运行效果和膜污染的情况,并从微生物角度分析了引起膜污染的因素.结果表明,低温时COD上清液和出水平均去除率分别为85%和92%,发生丝状菌污泥膨胀后去除率变化不大.MBR中丝状菌污泥膨胀形成的过程中,污泥沉降性变差,丝状菌丰度（FI）由2增加到5,丝状菌伸出絮体形成网状结构.低温时膜操作压力随时间呈直线变化,膜组件的水力清洗周期为15 d.在丝状菌大量繁殖时缩短到7 d,膜污染严重.通过测定活性污泥的特性,发现膨胀污泥的胞外聚合物（EPS）总量是正常污泥的3倍,污泥絮体相对疏水性（RH）随FI的提高而增大.EPS和RH增大后会引起更多物质沉积到膜表面,使膜污染速率提高,膜的运行周期变短.进一步的分析表明,混合液粘度、Zeta电位、污泥絮体形态也是影响膜污染的因素.     

济宁市生态文明建设的战略构想与对策

推进生态文明建设、建设美丽中国成为社会主旋律.文章从生态资源、生态空间、生态产业、转型发展等方面分析了济宁生态文明建设的优势,从战略顶层设计角度出发,研究提出了生态文明建设的总体要求、生态功能分区定位和实施步骤,针对近期济宁市生态文明建设存在的问题,从体制创新、制度体系、转型升级、考核监督、大气治理、水污染防治、城乡绿化等方面提出了具体的对策建议.     

关于实施挥发性有机物总量控制的几点思考

国家提出对挥发性有机物排放进行总量控制,本文从挥发性有机物的定性、定量、检测等方面分析了目前存在的困难和问题,并提出了初步建议。     

Conceptual study on incorporating user information into forecasting systems

The purpose of improving weather forecast is to enhance the accuracy in weather prediction. An ideal forecasting system would incorporate user-end information. In recent years, the meteorological community has begun to realize that while general improvements to the physical characteristics of weather forecasting systems are becoming asymptotically limited, the improvement from the user end still has potential. The weather forecasting system should include user interaction because user needs may change with different weather. A study was conducted on the conceptual forecasting system that included a dynamic, user-oriented interactive component. This research took advantage of the recently implemented TIGGE (THORPEX interactive grand global ensemble) project in China, a case study that was conducted to test the new forecasting system with reservoir managers in Linyi City, Shandong Province, a region rich in rivers and reservoirs in eastern China. A self-improving forecast system was developed involving user feedback throughout a flood season, changing thresholds for flood-inducing rainfall that were responsive to previous weather and hydrological conditions, and dynamic user-oriented assessments of the skill and uncertainty inherent in weather prediction. This paper discusses ideas for developing interactive, user-oriented forecast systems.