New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals

The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2+and Zn2+in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients(above 0.99 for both metal ions) and insignificant lack of fit(p = 0.0838 and 0.0782 for Pb2+and Zn2+, respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation(between –NH2,-CN and metal ions) and ion-exchange(between –COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.     

农村供水微污染水源特征及处理技术研究

农村水环境状况日益恶化,饮用水水源受到严重威胁,供水水源出现不同程度的微污染,农村微污染水源水的污染指标以高锰酸盐指数和氨氮为主.由于农村供水的特殊性,需要研究适合村镇供水实际的微污染原水处理技术,文章重点分析了目前常用的微污染原水净化的技术,从中提出适合农村微污染水源水处理的技术方案.文章经过分析认为,采用强化混凝和强化过滤,吸附预处理和生物预处理是适合农村微污染水源水处理的技术;深度处理通常不适合农村供水.     

温岭市高架道路交通噪声空间分布规律与防治对策研究

为评价温岭市东环高架道路交通噪声的环境影响,采用实测法对东环高架附近代表性点位及不同时间段进行噪声监测,记录等效连续A声级(Leq),以及同步监测车流量、车型等相关数据.根据《声环境质量标准》(GB 3096-2008),由所得监测数据,推测其交通噪声空间分布规律.结果表明,噪声最大值发生于上下班高峰期,交通噪声则随距离的增加而衰减,而道路两侧高层建筑交通噪声随着高度的增加先由小变大后变小.此外,还为该高架道路交通噪声的防治提供一定的参考依据.     

Methane Emissions and Production Potentials of Forest Swamp Wetlands in the Eastern Great Xing’an Mountains, Northeast China

Measurements of methane flux at a few inundated sites in China have been extrapolated to obtain estimates on a national scale. To enable those national estimates to be refined and to compare flux from geographically separated sites comprising the same wetland types, we used a closed chamber method to measure methane flux in uninundated Betula platyphylla—and Larix gmelinii—dominated peatlands in the Northeast China. Our measurements were taken from both vegetated and bare soil surfaces, and we compared flux with environmental measures including vegetation biomass, soil temperature and soil characteristics. We found that methane flux was low, and that there were no significant differences between wetland types, indicating that environmental influences were dominant. We found that flux was positively correlated to temperature in the surface layers of the soil, the above-ground biomass of the shrub and herb layers, total soil carbon and total soil nitrogen; and we suggest that emissions may be due to anaerobic microcosms in the surface layers. The methane production potentials of the soils were low and similar between both sites but inconsistent with the differences between fluxes, and inconsistent with production potentials and fluxes reported from the same wetland types elsewhere, indicating that there were subtle environmental differences between wetlands classed as being of the same type. Differences between fluxes in vegetated chambers with bare soil chambers were insignificant, indicating that no methane emission through aerenchyma occurred at our sites. We concluded that wetland type was not an accurate predictor of methane flux.     

页岩气开发中压裂返排液的水质污染特征研究

页岩气压裂返排液成分复杂,为了解页岩气开采过程中压裂返排液的污染情况,对四川某页岩气典型井场不同时期的压裂返排液污染物组成进行了分析,采用超滤膜法测定溶解性有机物(DOM)相对分子质量分布特性,通过建立水质矩阵开展污染特性评价,并进行了综合生态毒性研究。结果表明,该区域不同时期压裂返排液中污染物特征相似,主要污染因子为总有机碳(TOC)和氯离子,并且生物毒性高、可生化性差。研究结果可为该区域压裂返排液处理技术的选择提供参考。     

Two-phase modeling of sediment clouds

A sediment cloud release in stagnant ambient fluid occurs in many engineering applications. Examples include land reclamation and disposal of dredged materials. The detailed modeling of the distinct characteristics of both the solid and fluid phases of the sediment cloud is hitherto unavailable in the literature despite their importance in practice. In this paper, the two-phase mixing characteristics of the sediment cloud are investigated both experimentally and theoretically. Experiments were carried out to measure the transient depth penetration and the lateral spread of the sediment cloud and its entrained fluid using the laser induced fluorescence technique, with a range of particle sizes frequently encountered in the field (modeled at laboratory scale). A two-phase model of the sediment cloud that provides detailed predictions of the mixing characteristics of the individual phases is also proposed. The entrained fluid characteristics are solved by an integral model accounting for the buoyancy loss (due to particle separation) in each time step. The flow field induced by the sediment cloud is approximated by a Hill’s spherical vortex centered at the centroid and with the size of the entrained fluid. The particle equation of motion under the effect of the induced flow governs each computational particle. A random walk model using the hydrodynamic diffusion coefficient is used to account for the random fluctuation of particles in the dispersive regime. Overall, the model predictions of the two-phase mixing characteristics are in good agreement with the experimental data for a wide range of release conditions.     

Preparation of various thiol-functionalized carbon-based materials for enhanced removal of mercury from aqueous solution

In this work, biochar (BC), activated carbon (AC), and graphene oxide (GO) were thiol-functionalized using 3-mercaptopropyltrimethoxysilane (3-MPTS) (named as BCS, ACS, and GOS, respectively). BCS, ACS, and GOS were synthesized mainly via the interaction between hydrolyzed 3-MPTS and surface oxygen-containing functional groups (e.g., –OH, O–C=O, and C=O) and π-π interaction. The materials before and after modification were characterized and tested for mercury removal, including sorption kinetics and isotherms, the effects of adsorbent dosage, initial pH, and ionic strength. Pseudo-second-order sorption kinetic model (R² = 0.992~1.000) and Langmuir sorption isotherm model (R² = 0.964~0.998) fitted well with the sorption data of mercury. GOS had the most –SH groups with the largest adsorption capacity for Hg²⁺ and CH₃Hg⁺ (449.6 and 127.5 mg/g), followed by ACS (235.7 and 86.7 mg/g) and BCS (175.6 and 30.3 mg/g), which were much larger than GO (96.7 and 4.9 mg/g), AC (81.1 and 24.6 mg/g), and BC (95.6 and 9.4 mg/g). GOS and ACS showed stable mercury adsorption properties at a wide pH range (2~9) and ionic strength (0.01~0.1 mol/L). Mercury maybe removed by ligand exchange, surface complexation, and electrostatic attraction.

     

在用吊运熔融金属起重机主起升钢丝绳缠绕系统的优化研究

结合最新的相关安全规程要求,通过对在用吊运熔融金属起重机钢丝绳缠绕系统的分析、研究,依据起重机械设计规范,对不同工况下钢丝绳缠绕系统分别提出两套优化方案,并通过实际应用情况验证优化方案的可行性。     

Sustainability of a local government-instituted ecotourism development: Tayak adventure,nature and wildlife Park in Rizal,Laguna, Philippines

Environment, Development and Sustainability - Ecotourism development is a strategy of the Philippine Government. The existence of untapped natural resources and cultural/heritage assets has impeded...     

洪水作用下汽车的起动流速研究

针对洪水作用下汽车的起动条件开展了一系列的研究:首先分析部分淹没状态下汽车的受力情况,结合滑动平衡的临界起动条件建立相关方程,导出了洪水中汽车起动流速公式;然后在室内水槽中对三款模型车进行了一系列的起动试验。试验结果表明:对于同一款模型车,平行于水流方向放置时,起动流速与水深的相关性较好;并且水深越大,起动流速越小。接着运用试验资料率定了起动流速公式中的相关参数。最后采用模型相似率及率定后的计算公式估算了原型车辆在不同水深下的起动流速,两种方法所得的结果较为接近,故预测结果较为可靠。