Removal of mercury from aqueous solutions using activated carbon prepared from agricultural by-product/waste

Removal of mercury from aqueous solutions using activated carbon prepared from Ceiba pentandra hulls, Phaseolus aureus hulls and Cicer arietinum waste was investigated. The influence of various parameters such as effect of pH, contact time, initial metal ion concentration and adsorbent dose for the removal of mercury was studied using a batch process. The experiments demonstrated that the adsorption process corresponds to the pseudo-second-order-kinetic models and the equilibrium adsorption data fit the Freundlich isotherm model well. The prepared adsorbents ACCPH, ACPAH and ACCAW had removal capacities of 25.88 mg/g, 23.66 mg/g and 22.88 mg/g, respectively, at an initial Hg(II) concentration of 40 mg/L. The order of Hg(II) removal capacities of these three adsorbents was ACCPH > ACPAH > ACCAW. The adsorption behavior of the activated carbon is explained on the basis of its chemical nature. The feasibility of regeneration of spent activated carbon adsorbents for recovery of Hg(II) and reuse of the adsorbent was determined using HCl solution.     

Sorption of cadmium and zinc from aqueous solutions by zeolite 4A, zeolite 13X and bentonite

The sorption and desorption of cadmium and zinc on zeolite 4A, zeolite 13X and bentonite has been studied using batch sorption studies. Parameters such as equilibrium time, effect of pH and sorbent dose were studied. The sorbents exhibited good sorption potential for cadmium and zinc with a peak value at pH 6.0 and 6.5, respectively. The sorption followed the Freundlich sorption model. More than 70% sorption occurred within 20 min and equilibrium was attained at around 90 min for the three sorbents. The metals sorption by zeolite 4A was higher than that by zeolite 13X and bentonite. The desorption studies were carried out using NaCl solution and the effect of NaCl concentration on desorption was also studied. Maximum desorption of 76% for cadmium and 80% for zinc occurred with 10% NaCl.     

Controlled release,blind tests of DNAPL characterization using partitioning tracers

The partitioning tracer technique for dense nonaqueous phase liquid (DNAPL) characterization was evaluated in an isolated test cell, in which controlled releases of perchloroethylene (PCE) had occurred. Four partitioning tracer tests were conducted, two using an inverted, double five-spot pumping pattern, and two using vertical circulation wells. Two of the four tests were conducted prior to remedial activities, and two were conducted after. Each test was conducted as a "blind test" where researchers conducting the partitioning tracer tests had no knowledge of the volume, method of release, nor resulting spatial distribution of DNAPL. Multiple partitioning tracers were used in each test, and the DNAPL volume estimates varied significantly within each test based on the different partitioning tracers. The tracers with large partitioning coefficients generally predicted a smaller volume of PCE than that expected based on the actual release volume. However, these predictions were made for low DNAPL saturations (average saturation was approximately 0.003), under conditions near the limits of the method's application. Furthermore, there were several factors that may have hindered prediction accuracy, including tracer degradation and remedial fluid interference.     

生物法处理挥发性有机废气的研究

生物法处理被污染的空气这一技术已经被德国和荷兰成功地运用了 2 0年之久 ,但是在国内还属于一种较新的空气污染治理技术。本文主要概述了有机废气生物处理的 3种主要形式 :生物滤池、生物滴滤塔和生物洗涤器的原理、流程和几种影响反应器性能的因素 ,并比较了以上 3种反应器及其不同支撑材料的优缺点。目前 ,气态生物反应器主要以通用的指导方针、试验性的研究和来自类似应用的经验为基础进行设计的。     

Design of aquifer remediation systems: (2) estimating site-specific performance and benefits of partial source removal

A Lagrangian stochastic model is proposed as a tool that can be utilized in forecasting remedial performance and estimating the benefits (in terms of flux and mass reduction) derived from a source zone remedial effort. The stochastic functional relationships that describe the hydraulic "structure" and non-aqueous phase liquid (NAPL) "architecture" have been described in a companion paper (Enfield, C.G., Wood, A.L., Espinoza, F.P., Brooks, M.C., Annable, M., Rao, P.S.C., this issue. Design of aquifer remediation systems: (1) describing hydraulic structure and NAPL architecture using tracers. J. Contam. Hydrol.). The previously defined functions were used along with the properties of the remedial fluids to describe remedial performance. There are two objectives for this paper. First, is to show that a simple analytic element model can be used to give a reasonable estimate of system performance. This is accomplished by comparing forecast performance to observed performance. The second objective is to display the model output in terms of change in mass flux and mass removal as a function of pore volumes of remedial fluid injected. The modelling results suggest that short term benefits are obtained and related to mass reduction at the sites where the model was tested.     

Monitoring of Hydrocarbon Emissions in a Petroleum Refinery

In a petroleum refinery the hydrocarbon emissions which are mostly fugitive in nature are emitted from process, offsites and periodic accidental releases such as: materials storage & handling, process, equipment leaks, solvent evaporation, combustion sources, waste treatment etc. In India, the monitoring of such emissions in a refinery are limited as also the standards are not set for its limit in ambient air. Hence there is an urgent need for generating a database for such emissions. Recently in India, MoEF/CPCB has set some guidelines under CREP rules for monitoring such emissions in a refinery. A detailed monitoring of the hydrocarbon emissions from different sources in a typical 10.5 MMTPA Indian refinery is undertaken during 1999–2001 and the results are presented. It is observed that the storage tank emissions alongwith process leaks form the major contributor towards fugitive hydrocarbon emissions.     

Effect of particulate matters on inactivation of bacteriophage MS2 under irradiation above 320 nm

Environmental Science and Pollution Research - The inactivation of bacteriophage MS2 under irradiation above 320 nm was investigated, focusing on different solution pH, ionic strength, and...     

Washing of marine coastal sand in a batch reactor: sorption and desorption of BTEX

This study addresses the issues related to decontamination of marine beach sand accidentally contaminated by petroleum products. Sorption and desorption of BTEX (i.e., benzene, toluene, ethylbenzene, and xylene) onto the sand from Uran Beach, located near the city of Mumbai, India, were studied, and isotherms were determined using the bottle point method to estimate sorption coefficients. Alternatively, QSARs (i.e., quantitative structure activity relationships) were developed and used to estimate the sorption coefficients. Experiments for kinetics of volatilization as well as for kinetics of sorption and desorption in the presence of volatilization were conducted in a fabricated laboratory batch reactor. A mathematical model describing the fate of volatile hydrophobic organic pollutants like BTEX (via sorption and desorption in presence of volatilization) in a batch sediment-washing reactor was proposed. The experimental kinetic data were compared with the values predicted using the proposed models for sorption and desorption, and the optimum values of overall mass transfer coefficients for sorption (K(s)a(s)) and desorption (K(d)a(d)) were estimated. This was achieved by minimization of errors while using the sorption coefficients (Kp) obtained from either laboratory isotherm studies or the QSARs developed in the present study. Independent experimental data were also collected and used for calibration of the model for volatilization, and the values of the overall mass transfer coefficient for volatilization (K(g)a(g)) were estimated for BTEX. In these exercises of minimization of errors, comparable cumulative errors were obtained from the use of Kp values derived from experimental isotherms and QSARs.     

Weather integrated malaria prediction system using Bayesian structural time series model for northeast states of India

Environmental Science and Pollution Research - Malaria is an endemic disease in India and targeted to eliminate by the year 2030. The present study is aimed at understanding the epidemiological...     

基于非本地物种毒性数据推导出的水质基准可为本地物种提供适当保护吗？

基于非本地物种的毒性数据推导出的水质基准一直存在争议,质疑者提出应有针对不同生物区系的水质基准。而这个问题在中国尤为突出。本文作者搜集了38种污染物对本地物种和非本地物种的毒性数据,比较了这些生物的HC₅和物种敏感度分布,结果显示,基于非本地物种推导的水质基准有74%的确定性可以有效保护中国的水生态系统。如果采用评价因子(AF=5)来校正基准,那么可以获得90%的确定性。
精选自Xiaowei Jin, Zijian Wang, Yeyao Wang, Yibing Lv, Kaifeng Rao, Wei Jin, John P. Giesy and Kenneth M. Y. Leung. Do water quality criteria based on nonnative species provide appropriate protection for native species? Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2985
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2985/full