Electronic waste recycling: A review of U.S. infrastructure and technology options

The useful life of consumer electronic devices is relatively short, and decreasing as a result of rapid changes in equipment features and capabilities. This creates a large waste stream of obsolete electronic equipment, electronic waste (e-waste).Even though there are conventional disposal methods for e-waste, these methods have disadvantages from both the economic and environmental viewpoints. As a result, new e-waste management options need to be considered, for example, recycling. But electronic recycling has a short history, so there is not yet a solid infrastructure in place.In this paper, the first half describes trends in the amount of e-waste, existing recycling programs, and collection methods. The second half describes various methods available to recover materials from e-waste. In particular, various recycling technologies for the glass, plastics, and metals found in e-waste are discussed. For glass, glass-to-glass recycling and glass-to-lead recycling technologies are presented. For plastics, chemical (feedstock) recycling, mechanical recycling, and thermal recycling methods are analyzed. Recovery processes for copper, lead, and precious metals such as silver, gold, platinum, and palladium are reviewed. These processes are described and compared on the basis of available technologies, resources, and material input–output systems.     

Comparison of PM2.5 and PM10 in A Suburban Area in Korea During April, 2003

Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003. PM_2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM₁₀ (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM_2.5 and PM₁₀ mass measured were 37.3 ± 16.2 μg m⁻³ and 60.8 ± 29.5 μg m⁻³, respectively. The sum of ionic chemical species concentrations for PM_2.5 and PM₁₀ was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m³, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM_{2.5 − 10}) particles, but less reduction was found for fine (PM_2.5) mass concentration. SO₄ ²⁻, NH₄ ⁺, and K⁺ predominated in fine particulate mode, NO₃ ⁻ and Cl⁻ predominated in fine particle mode and coarse particle mode, but Na⁺, Mg²⁺, and Ca²⁺ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass concentrations of PM₁₀ in daytime and at night were 57.6 and 70.0 μg m⁻³, and those of PM_2.5 were 35.4 and 42.5 μg m⁻³, respectively. NO₃ ⁻ and Cl⁻ in both PM_2.5 and PM₁₀ were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations. In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea, along with a relatively low PM concentration.     

污水生物除磷研究进展

水体富营养化是世界性难题,其中磷通常是主要限制因子.生物除磷工艺简单,污泥产量少,可节约能源,运行费用也较低,便于操作和磷的回收.在介绍水体中磷的来源、污染特点及其造成危害的基础上,着重综述了国内外生物除磷的研究进展,并对生物除磷存在的问题和发展趋势提出了一些看法.     

长江经济带科技创新资源集聚能力空间格局及网络结构

随着科技创新资源由技术推动和需求拉动的线性模式转向合作的空间网络模式,探究其空间格局及网络结构特征,剖析空间格局及网络结构形成的原因,对区域实现科技创新引领发展具有重要意义.基于ArcGIS可视化和社会网络分析法对2004～2017年长江经济带科技创新资源集聚能力的空间格局及网络结构特征进行分析,结果显示:(1)长江经济带科技创新资源集聚能力呈现逐渐增强的态势,两极分化现象严重,由东向西梯次变弱,且具有明显"领导型—追赶型—跟随型"的特征;(2)科技创新资源集聚能力空间网络联系愈来愈密集,网络密度呈现下降趋势,网络等级、网络效率均呈现上升趋势;(3)中心度排名前十位城市的科技创新资源集聚能力与其他城市空间网络联系较多,并在网络中处于中心位置和扮演支配者角色;(4)包含上海、苏州等33个城市的板块一属于"净溢出"板块,包含重庆、成都等26个城市的板块二属于"双向溢出"板块,包含武汉、长沙等41个城市的板块三属于"经纪人"板块,包含贵阳、昆明等29个城市的板块四属于"净受益"板块.鉴于此,从大力发展新型基础设施建设、促进核心城市科技创新驱动和推进科技创新资源合作平台的构建等方面提出了政策建议.     

深圳地铁一期工程施工安全管理概况

我国越来越多城市正在新建、扩建或计划建设地铁,而地铁安全生产文明施工是值得地铁工程建设安全生产责任单位非常关注、重视的课题.结合安全生产有关法律法规,重点针对建设单位在建设工程中的安全责任,介绍深圳地铁一期工程的主要安全管理工作.     

环境科学研究与科研人员的智力结构

本文结合环境科研的全方位交叉和渗透、环境问题的滞后与环境科研的尾随性、环境问题的整体性层次性与科研选题的系统配套、环境问题与环境科研的国际性等特点,分析论证了建立以科研人员个体为基础并以科研群体来完善的四维模型知识结构的必要性。 接着,在讨论知识结构与智力结构的区别和联系之后,作者从环境科研特点和实践经验出发,系统地论述了科研人员应有的智力结构、智力结构优化与个性心理品质、个体智力结构优化与群体智力结构的最佳配置问题。 作者最后强调,为了多水平的科研成果和人才,必须高度重视科研人员的智力发展和智力效应这个根本条件。      

Alleviation of atrazine toxicity to maize seedlings grown in soils with amendment of biochar derived from wheat under different temperatures

Environmental Science and Pollution Research - The effects of different biotransformation temperatures (250, 550, and 850 °C) and different dose (0–1%) of biochar on the physiological...     

Short-term effects of particulate matter exposure on emergency room visits for cardiovascular disease in Lanzhou,China: a time series analysis

Environmental Science and Pollution Research - Cardiovascular disease (CVD) has been the leading cause of death in China. Identifying the relationship between particulate matter (PM) and CVD in...     

Quantitative analysis of the relationship between land use and urbanization development in typical arid areas

Environmental Science and Pollution Research - As the most sensitive and typical oasis city in the arid region of China, Jiayuguan, the role of land use change and urbanization in this region is...     

Use of a broad β-diversity measure of pelagic ciliate communities for assessing vertical heterogeneity of water columns in the Pacific Arctic Ocean

Environmental Science and Pollution Research - Multivariate dispersion has proven to be a broad β-diversity measure that shows the heterogeneity of environmental conditions. The dispersion...