Enhanced 4-chlorophenol biodegradation by integrating Fe2O3 nanoparticles into an anaerobic reactor: Long-term performance and underlying mechanism

• 4-chlorophenol biodegradation could be enhanced in Fe₂O₃ coupled anaerobic system. • Metabolic activity and electron transport could be improved by Fe₂O₃ nanoparticles. • Functional microbial communities could be enriched in coupled anaerobic system. • Possible synergistic mechanism involved in enhanced dechlorination was proposed. Fe₂O₃ nanoparticles have been reported to enhance the dechlorination performance of anaerobic systems, but the underlying mechanism has not been clarified. This study evaluated the technical feasibility, system stability, microbial biodiversity and the underlying mechanism involved in a Fe₂O₃ nanoparticle-coupled anaerobic system treating 4-chlorophenol (4-CP) wastewater. The results demonstrated that the 4-CP and total organic carbon (TOC) removal efficiencies in the Fe₂O₃-coupled up-flow anaerobic sludge blanket (UASB) were always higher than 97% and 90% during long-term operation, verifying the long-term stability of the Fe₂O₃-coupled UASB. The 4-CP and TOC removal efficiencies in the coupled UASB increased by 42.9±0.4% and 27.5±0.7% compared to the control UASB system. Adding Fe₂O₃ nanoparticles promoted the enrichment of species involved in dechlorination, fermentation, electron transfer and acetoclastic methanogenesis, and significantly enhanced the extracellular electron transfer ability, electron transport activity and conductivity of anaerobic sludge, leading to enhanced 4-CP biodegradation performance. A possible synergistic mechanism involved in enhanced anaerobic 4-CP biodegradation by Fe₂O₃ nanoparticles was proposed.     

Impact of anthropogenic heat emissions on meteorological parameters and air quality in Beijing using a high-resolution model simulation

• The Large scale Urban Consumption of energY model was updated and coupled with WRF. • Anthropogenic heat emissions altered the precipitation and its spatial distribution. • A reasonable AHE scheme could improve the performance of simulated PM_2.5. • AHE aggravated the O₃ pollution in urban areas. Anthropogenic heat emissions (AHE) play an important role in modulating the atmospheric thermodynamic and kinetic properties within the urban planetary boundary layer, particularly in densely populated megacities like Beijing. In this study, we estimate the AHE by using a Large-scale Urban Consumption of energY (LUCY) model and further couple LUCY with a high-resolution regional chemical transport model to evaluate the impact of AHE on atmospheric environment in Beijing. In areas with high AHE, the 2-m temperature (T₂) increased to varying degrees and showed distinct diurnal and seasonal variations with maxima in night and winter. The increase in 10-m wind speed (WS₁₀) and planetary boundary layer height (PBLH) exhibited slight diurnal variations but showed significant seasonal variations. Further, the systematic continuous precipitation increased by 2.1 mm due to the increase in PBLH and water vapor in upper air. In contrast, the precipitation in local thermal convective showers increased little because of the limited water vapor. Meanwhile, the PM_2.5 reduced in areas with high AHE because of the increase in WS₁₀ and PBLH and continued to reduce as the pollution levels increased. In contrast, in areas where prevailing wind direction was opposite to that of thermal circulation caused by AHE, the WS₁₀ reduced, leading to increased PM_2.5. The changes of PM_2.5 illustrated that a reasonable AHE scheme might be an effective means to improve the performance of PM_2.5 simulation. Besides, high AHE aggravated the O₃ pollution in urban areas due to the reduction in NO_x.     

冷循环便携式半导体降温服设计及制冷性能分析

为缓解高温环境下劳动人员面临的热害问题,设计1种利用半导体制冷片作为制冷源的便携式冷循环降温服,并在高温环境下测试其降温性能.结果表明:在总电源功率100 W、环境温度30℃的情况下,运行12 min后,制冷水温度降低至15.7℃.降温服稳定运行状态下制冷功率为340.4 W.系统运行环境温度对制冷系统的制冷性能有显著...     

余热锅炉在绿色油田建设中的应用

余热锅炉的运用使得不同品级的能源可以得到充分合理的利用。中国石油塔里木油田公司在生产实践中,采用燃气发电机组—余热锅炉联合循环技术,用不能再发电的燃气尾气生产蒸汽,对天然气中蕴含的能量进行分级利用,实现了发电、供热双重效益,也降低了对周边环境的热污染。文章对该热电联合循环的工艺流程进行介绍,通过对燃气发电机组尾气的能量传递进行计算,用热力学原理进行分析,以期实现对使用余热锅炉后的热电联产经济性进行综合评价的目的。     

A material and energy flow model for co-production of heat and power

Co-production of electricity, district heat and industrial heat/process steam (heat and power, CHP) has been applied to a large, national scale, in only a few countries in the world, Denmark, The Netherlands and Finland. In this production method, the waste energy from electricity production is used in two quality levels. First, industrial process steam requirements can be met with this residual energy. Second, the waste energy is used in local district heating networks for households and other buildings in a city. In this integrated production method, a total fuel efficiency of 85% can be achieved. Through the technique of fluidized bed combustion, modern CHP plants can use coal and oil, and in addition, heterogeneous fuels such as biomass, industrial wastes and recycled fuels from households. In this paper, the CHP method is considered in terms of four categories of material and energy flows. For the purpose of considering the potential environmental gains and the difficulties of this production method when applied to integrated waste management and energy production, the four suggested categories are: matter (biomass) (1), nutrients (2), energy (3) and carbon (4). Corporate environmental management inventory tools, decision-making tools, management, organisational and administrative tools as well as information management tools that could be used in CHP-related material and energy flow management are shortly discussed. It is argued that for CHP energy and environmental management, it can be important to adopt an approach to networks of firms, rather than to an individual firm. The presented material and energy flow model may contribute to assessing, planning and implementing of CHP-based waste management and cleaner energy production.     

高层建筑安全核区域防排烟技术探讨

本文在某高层安全核区域设计了一系列现场实验,通过送风系统和机械排烟的不同开启、关闭组合方式,定性判断送风与排烟的相互作用。结果显示：在送风量略大于排烟量的前提下,烟气层能够稳定在一定的高度,对人员的安全疏散是最有利的。因此,本文提出在满足楼梯间及其前室足够正压值的前提下,改造现有的送风系统,利用多余的正压值进行补气,以优化高层建筑内的防排烟效果。     

潜流湿地处理不同浓度有机污水的差异分析

通过供氧平衡及物质平衡理论分析和实证研究,探讨根系泌氧、水中自带溶解氧、植物吸收营养物在湿地净化中的贡献,并通过落空运行来启动大气复氧.结果表明,当处理Ⅳ类以下地表水时,根系泌氧和水中携氧可使基质内为好氧环境、出水DO>0;植物吸收和介质吸附可使N、P去除稳定.当处理生活污水时,植物供氧不足,基质内为缺氧/厌氧环境、铵氧化细菌和亚硝酸氧化菌数量只有氨化细菌的1/1 000～1/100,出水DO≈0,使基质易堵塞;植物吸收和介质吸附有限,氮去除率≤20%;磷去除率随介质吸附容量的饱和逐渐下降,运行前3个月去除率为54%,运行1a以后降低到5%.潜流湿地处理生活污水时污染负荷远大于植物供氧和吸收营养物的上限,是其存在技术局限的根本原因.启动大气复氧是湿地工艺改进的一个重要方向,预沉-常规湿地对COD、NH₄⁺-N、TN、TP的去除率为79%、34%、36%、34%,预沉-落空湿地则为79%、88%、14%、69%,必须合理利用大气复氧才能实现去除总氮的最终目的.     

Experimental Zn(II) retention in a sandy loam soil by very small columns

The use of column experiments, usually performed to better approximate field conditions, may provide information that is not available from batch experiments. In such experiments heavy metals are often adsorbed until saturation followed by desorption experiments. When the affinity of the metal to soil is high, the retention factor (R) could be greater than thousands and the duration of experiments can become impractically long. In order to use reasonable laboratory time, the flow rate should be increased or the column size decreased. The increase in flow rate produces undesirable kinetic and dispersion effects, so we used very small soil columns (pore volume = 0.31–0.70 ml) and relatively high flow rates (0.03–0.12 ml min⁻¹) in studies of Zn(II) adsorption and retention in soils. Conservative tracer flow column experiments under saturation conditions were carried out to determine flow parameters for different flow rates. Column pore volume (V_p), Peclet numbers (Pe) and longitudinal dispersion coefficients (D_L) were determined from breakthrough curves. The effect of type of electrolyte and ionic strength on the Zn(II) retention onto soil was determined. The influence of flow rate and bed height on the retention coefficient and on the mass transfer zone was also studied. The effect of different influent Zn(II) concentrations on the R values obtained was analyzed. Freundlich parameters from column experiments were compared with batch ones. The leaching efficiency of different electrolytes, salts of weak organic acids and EDTA was also studied.     

南水北调东线水资源配置中的期权契约研究

针对南水北调东线实际和传统水资源配置方法的局限性。借鉴金融工程的理念。引入水期权契约作为市场机制下水资源配置的一种方式．用以提高干旱年水供给保证率、规避水价波动风脸，从而提高东线水资源使用价值。分析期权契约理论用于南水北调水资源配置的可行性。并根据东线受水区流域水资源供求缺口的影响因素分析．得出水价的均值回复特性。在上述分析基础上引入多次执行期权契约。考虑应用动态规划方法对期权价值进行求解。并通过算例分析验证了该方法的可行性．最后根据南水北调东线实际构建了水期权契约在东线的应用流程。     

AN INTEGRATED APPROACH TO WATER RESOURCES DEVELOPMENT OF THE TEHRAN REGION IN IRAN1

ABSTRACT: In this paper, a system approach to water resources development in Tehran Metropolitan Area, with its complex system of water supply and demands, is discussed. Water resources in this region include water storage in the Lar, Latyan, and Karaj reservoirs, the Tehran aquifer, as well as water discharge in local rivers and in drainage channels (mainly supplied by urban runoff and wastewater). This study consists of three phases of long‐term water resources planning and management in the Tehran metropolitan area. In each phase, a different level of details among different components of the system is considered. In the first phase, optimal operating policies for Tehran reservoirs and a decision support system are developed. In the second phase, interactions between surface and ground water resources as well as surface runoffs and wastewater disposal in different subareas are investigated. The water table fluctuations as a result of implementing sewerage collection project was also simulated. In the last phase, long‐term scenarios for water resources and agricultural development in the Southern part of Tehran are defined, and the effects of each scenario on the quality and quantity of surface and ground water resources are studied.