磁混凝在水与废水处理领域的应用

磁技术作为一种高效的分离、净化方法在水与废水处理领域的作用和地位日益凸显,磁性接种、磁性吸附等水处理方法已受到了广泛关注;高场强、低能耗的磁分离器的相继问世和不断完善为高效稳定地进行磁分离提供了必要条件。基于上述考虑,将传统的混凝过程与磁技术有机结合而产生的磁混凝工艺将成为混凝发展的新方向之一。本文系统综述了磁混凝在水处理中的研究和应用,从颗粒物在磁场和重力场中的界面过程、相互作用机制,磁混凝在国内外的研究现状,以及磁分离器的研究进展等角度展开讨论,探讨了该技术面临的问题,并展望了其发展前景。     

Risk Assessment of Carbon Sequestration for Terrestrial Ecosystems in China

Climate change will alter the capacity of carbon sequestration,and the risk assessment of carbon sequestration for terrestrial ecosystems will be helpful to the decision-making for climate change countermeasures and international climate negotiations.Based on the net ecosystem productivity of terrestrial ecosystems simulated by Atmosphere Vegetation Integrated Model,each grid of the risk criterion was set by time series trend analysis.Then the risks of carbon sequestration of terrestrial ecosystems were investigated.The results show that,in the IPCCSRES-B2 climate scenario,climate change will bring risks of carbon sequestration,and the high-risk level will dominate terrestrial ecosystems.The risk would expand with the increase of warming degree.By the end of the long-term of this century,about 60% of the whole country will face the risk;Northwest China,mountainous areas in Northeast China,middle and lower reaches plain of Yangtze River areas,Southwest China and Southeast China tend to be extremely vulnerable.Risk levels in most regions are likely to grow with the increase of warming degree,and this increase will mainly occur during the near-term to mid-term.Northwest China will become an area of high risks,and deciduous coniferous forests,temperate mixed forests and desert grassland tend to be extremely vulnerable.     

改性硅藻土复合混凝剂处理深度采油废水

某油田深度采油废水中含有大量残油,粘度大、乳化程度高、油水分离困难,本实验采用改性硅藻土吸附和无机混凝剂混凝相结合以处理深度采油废水.结果表明,对于含油浓度为250～ 350 mg/L的石油废水,用强化吸附方法,吸附剂投加量为1.5 g/L,优化实验条件下除油率可达到75％;采用强化混凝的方法,PAC在投药量为200 mg/L的情况下除油率可达到87％;采用强化吸附-混凝联合处理的优化方法,投加0.7 g/L吸附剂+PAC 200 mg/L,除油率＞95％,明显高于吸附和混凝单独处理效果,大大改善了出水水质.     

The dust retention capacities of urban vegetation—a case study of Guangzhou, South China

Urban vegetation increasingly plays an important role in the improvement of the urban atmospheric environment. This paper deals with the dust retention capacities of four urban tree species (Ficus virens var. sublanceolata, Ficus microcarpa, Bauhinia blakeana, and Mangifera indica Linn) in Guangzhou. The dust-retaining capacities of four tree species are studied under different pollution intensities and for different seasons. Remote sensing imagery was used to estimate the total aboveground urban vegetation biomass in different functional areas of urban Guangzhou, information that was then used to estimate the dust-retaining capacities of the different functional areas and the total removal of airborne particulates in urban Guangzhou by foliage. The results showed that urban vegetation can remove dust from the atmosphere thereby improving air quality. The major findings are that dust retention, or capture, vary between the four species of tree studied; it also varied between season and between types of urban functional area, namely industrial, commercial/road traffic, residential, and clean areas. Dust accumulation over time was also studied and reached a maximum, and saturation, after about 24 days. The overall aboveground biomass of urban vegetation in Guangzhou was estimated to be 52.0?×?10⁵ t, its total leaf area 459.01 km², and the dust-retaining capacity was calculated at 8012.89 t per year. The present study demonstrated that the foliage of tree species used in urban greening make a substantial contribution to atmospheric dust removal and retention in urban Guangzhou.     

Vegetation distribution on Tibetan Plateau under climate change scenario

The impact of climate change on distribution of vegetation is an important aspect in studies on the responses of ecosystems to the climate change. Particularly in the sensitive environments of the Tibetan Plateau, vegetation distribution may be significantly affected by climate change. In this research, the coupled biogeography and biogeochemistry model, BIOME4, was modified according to the features of vegetation distribution on the Plateau, and the Kappa statistic was used to evaluate the modeling results by comparing the simulated vegetation distribution with the existing 1:1,000,000 vegetation map of China. The comparison showed that modified model was appropriate for simulating the overall vegetation distribution on the Plateau. With the improved BIOME4 model, possible changes in the vegetation distribution were simulated under climate change scenarios. The simulated results suggest that alpine meadows, steppes, and alpine sparse/cushion vegetation and deserts would shrink, while shrubs, broad-leaved forests, coniferous-broad-leaved mixed forests, and coniferous forests would expand. Among these types, shrubs, alpine meadows, and steppes would change the most. The shrubs vegetation would expand toward the northwest, replacing most alpine meadows and part of steppes, and thus causing their shrinkages. Yet broad-leaved forests and coniferous-broad-leaved mixed forests demonstrated smaller changes in their distributions. For all the forest types, the area of coniferous forests would increase the most by spreading to the interior of the Plateau.     

超细化学纤维填料用于净化含油循环冷却水研究

研究了一种高比表面积化学纤维填料对泄漏于工业循环冷却水中机油的循环吸附效果.讨论了填料静态饱和吸附量和循环饱和吸附量的差别;考察了水中分散(或乳化)油的初始浓度、运行温度及pH值变化的条件下填料对循环吸附量和循环吸附能力的影响;比较了吸附前后填料的表面水接触角变化.实验结果表明,填料的循环饱和吸附量约是静态饱和吸附量的...     

污泥减量化技术研究进展

针对当前日益突出的污泥处理处置难等问题,分别从物理法、化学法和生物法等方面阐述了当前污泥减量化技术的研究发展现状,介绍了各种工艺的基本原理、特点和存在的问题.结合国内外污泥减量化技术的研究进展,提出了未来污泥减量化技术的发展方向.     

Al13形态分离纯化方法的初步研究

对ＳＯ＾２－４／Ｂａ＾２＋法分离提纯Ａｌ１３形态的影响因素进行了研究,实验结果表明,聚合铝浓度、ＳＯ４／Ａｌ比、Ｂａ／ＳＯ４摩尔比、以及超声反应时间对分离效果上具有较大的影响。较高浓度的聚合铝利于沉淀的形成与分离。同时选用１：１的ＳＯ４／Ａｌ与Ｂａ＾２＋的共存对形态分析不产生影响,形态鉴定结果表明,经过上述分离条件所得产物形态为Ａｌ１３。     

经济快速发展区域的城市植被叶面降尘粒径和重金属特征

以广东惠州和广州海珠区为例,用粒径分析仪和ICP-AES测定了城市不同功能区植被叶面降尘的粒径和重金属特征.结果表明,两地降尘粒径为对称分布,粒径均小于1 mm,60%粒径小于100μm.居住区、清洁区降尘颗粒小于商业交通区、工业区.降尘重金属,尤其Cd、Pb污染严重,惠州和广州降尘含量分别为Cd:6.8～12.8 mg·kg-1,8.8～13.0mg·kg-1;Pb:434～512mg·kg-1,584～1182 mg·kg-1.不同功能区重金属含量差异显著,污染水平递减顺序为:工业区、商业交通区、居住区、清洁对照区.降尘中重金属元素富集因子为18～746,反映其主要源于工业污染、交通排放、建筑物腐蚀剥落等人为源.叶面降尘与路尘以及叶面降尘之间大部分重金属显著相关,表明降尘和路尘重金属均来自外源输入.     

絮体分形结构形成机制探讨

基于统计力学和无标度网络框架分析了絮凝过程,并从物理角度导出了絮体的分形结构,探讨了分形维数与外界控制条件的关系.在此基础之上,根据能量守恒对模型进行了理论计算,发现在湍流条件或外界能量交换强烈的情况下,分形维数较高;反之,若在层流条件或能量交换较弱的条件下,则分形维数较低.将理论计算结果与实验结果进行比较,二者较为一致.