Ammonium removal by modified zeolite from municipal wastewater

Ammonium removal by modified zeolite, H-form and Na-form zeolite, were examined by batch-type methods. The adsorption of ammonium on modified zeolite was exothermic process. The saturation adsorption capacity of ammonium on H-form and Na-form zeolite were 21.23 and 41.1.5 mg/g, respectively. After ten times adsorption-desorption-readsorption cycles the standard deviations of H-form and Na-form zeolite were 6.34% and 6.59%. The zeolite adsorption process has proved cost effective and practical in reducing ammonium by H-form and Na-form zeolite in municipal wastewater from concentration 27.68 mg/L to 2.80 mg/L and 5.91 mg/L.     

Urban regeneration and democratization of information access: CitiStat experience in Baltimore

This article explores the potential of a GIS-based approach to city management - Baltimore's CitiStat e-government program - for meeting the goals of sustainable urban regeneration. The argument advocated here builds on the widely held recognition that the application of ICTs in general can lead to both new forms of inclusion and exclusion of citizens. Therefore attending to the 'digital divide' is a relevant issue because cities are complex environments where outcomes of interventions are uncertain and widening participative arenas to different actors can increase the possibilities to regenerate declining urban areas in a more democratic way.     

纸塑铝复合包装废物的回收与再生利用现状

通过对典型的垃圾填埋场和复合包装再生利用企业的调研,分析了我国现有复合包装废物产生与回收再生利用的现状.并针对纸塑铝复合包装材料的结构和特点,对现有复合包装材料的再生利用技术进行研究比较,指出了我国复合包装回收利用过程中亟待解决的问题及未来的研究方向.     

2000年北京沙尘暴源地解析

2000年我国北方春季干旱少雨,气温回升快,低涡频繁侵入,4月3～9日连续3次冷空气活动,造成了北京地区严重的沙尘暴天气。笔者利用卫星云图和中尺度数值模式MM5,分析了该次沙尘暴源地及沙尘输送机制。结果证明,北京沙尘暴初始源地为蒙古高原及冷涡移动路径上的沙漠戈壁地区;北京周边地区裸露地的沙尘在气旋尾部上升气流的扰动下,亦形成了边界层的近距离输送。      

天然沸石生物再生途径机理研究

在模拟沸石床系统中,对比探讨了曝气、异养菌和硝化细菌3个因素单独或共同作用对沸石再生效果的影响.结果表明,在本试验条件下,曝气作用、异养菌代谢和硝化作用分别可将沸石的再生效率提高0.5%~1.0%、20.9%~31.1%和120%~180%,3个因素影响大小依次为硝化细菌＞异养菌＞曝气吹脱.当异养菌与硝化细菌共存时具有协同再生作用,不仅可提高系统的再生效率(接近100%),而且还可提高沸石的再生率(约10%).离子交换、曝气和异养菌单独或共同作用下沸石的再生过程可用y =1-e-kx方程模拟;存在硝化细菌作用时沸石的再生过程前、后段分别用线性方程y =kx和Monod方程拟合(R2＞0.99).结合沸石再生前后表观形态变化的观测,探讨了沸石的再生机理.     

海泡石颗粒的制备及其吸附油烟效能的研究

用X射线衍射分析了原海泡石矿的纯度,根据原海泡石特性提出“分散-提纯-活化-成型”的制备海泡石颗粒的工艺流程。用所制得的粒径为1.8海泡石颗粒进行油烟吸附实验,分析了海泡石吸附油烟的容量,绘出吸附穿透曲线,并提出海泡石吸附剂再生的方法,同时将海泡石与活性炭吸附油烟的效率做了对比实验。实验结果表明:海泡石成本低,油烟去除率高,是一种理想的油烟净化剂。     

Copper biosorption on immobilized seaweed biomass： Column breakthrough characteristics

The biosorption of copper by the brown seaweed Sargassum baccularia,immobilized onto polyvinyl alcohol(PVA)gel beads, was investigated with fixed-bed experiments.Laboratory-scale column tests were performed to determine breakthrough curves with varying flow rates and feed concentrations.A theoretical fixed-bed model,known as the Bohart-Adams equation,was evaluated in simulating the experimental breakthrough curves.The Bohart-Adams model qualitatively predicted the breakthrough trends.PVA- immobilized seaweed biomass beads were amenable to efficient regeneration with aqueous solution containing the chelating agent ethylenediaminetetraacetic acid(EDTA).The biosorbent retained most of its original uptake capacity over three cycles of use.The excellent reusability of the biosorbent could lead to the development of a viable metal remediation technology.     

Predicting landscape-scale biodiversity recovery by natural tropical forest regrowth

Natural forest regrowth is a cost-effective, nature-based solution for biodiversity recovery, yet different socioenvironmental factors can lead to variable outcomes. A critical knowledge gap in forest restoration planning is how to predict where natural forest regrowth is likely to lead to high levels of biodiversity recovery, which is an indicator of conservation value and the potential provisioning of diverse ecosystem services. We sought to predict and map landscape-scale recovery of species richness and total abundance of vertebrates, invertebrates, and plants in tropical and subtropical second-growth forests to inform spatial restoration planning. First, we conducted a global meta-analysis to quantify the extent to which recovery of species richness and total abundance in second-growth forests deviated from biodiversity values in reference old-growth forests in the same landscape. Second, we employed a machine-learning algorithm and a comprehensive set of socioenvironmental factors to spatially predict landscape-scale deviation and map it. Models explained on average 34% of observed variance in recovery (range 9–51%). Landscape-scale biodiversity recovery in second-growth forests was spatially predicted based on socioenvironmental landscape factors (human demography, land use and cover, anthropogenic and natural disturbance, ecosystem productivity, and topography and soil chemistry); was significantly higher for species richness than for total abundance for vertebrates (median range-adjusted predicted deviation 0.09 vs. 0.34) and invertebrates (0.2 vs. 0.35) but not for plants (which showed a similar recovery for both metrics [0.24 vs. 0.25]); and was positively correlated for total abundance of plant and vertebrate species (Pearson r = 0.45, p = 0.001). Our approach can help identify tropical and subtropical forest landscapes with high potential for biodiversity recovery through natural forest regrowth.