A potential new commercial method for processing leather to reduce environmental impact

INTRODUCTION: Current leather processing method involves dehairing and fibre opening employing lime and sulphide, which results in higher negative impact on the environment due to its uncleanness. This method of dehairing and fibre-opening process accounts for nearly 70-80% biochemical oxygen demand and chemical oxygen demand (COD) in tannery wastewater and also the generation of H(2)S gas. MATERIALS AND METHODS: Hence, an attempt has been made to reduce the environmental impact of the leather processing through a biochemical approach, employing proteolytic enzyme and sodium metasilicate for performing the above process more cleanly. RESULTS AND DISCUSSION: The developed process exhibits significant reduction in environmental parametres such as COD and total solid loads by 55% and 25%, respectively. This method completely avoids the formation of lime sludge. CONCLUSION: The functional properties of the leathers are also on par with conventionally processed leathers. Further, the process seems to be commercially viable.     

Temporal variation in the specific growth rate of bacterioplankton in the River Cauvery and its four down stream tributaries in Karnataka State, India

The temporal variation in the Specific Growth Rate (SGR) of natural population of heterotrophic bacterioplankton of the river Cauvery and its four down stream tributaries in Karnataka State was monitored over a period of two years from February 2000 to January 2002. The SGR was calculated by taking into account only the abundance of bacterioplankton at the beginning (0 h) and at the end (48 h) incubation period, at room or river temperature. The mean SGR was less and significantly different in the surface waters of river Kapila, Shimsha, Suvarnavathy and Arkavathy. But it was more and significantly different in river Cauvery when compared to other tributaries. This suggests that the river Cauvery was more favorable habitat for SGR of bacterioplankton than the other four watercourses studied. Investigation of interrelationship between SGR and other bacterial variables showed presence of only one correlation with direct counts of particle bound bacteria in river Arkavathy. Further, the relationship between SGR of bacterioplankton and other environmental variables showed the presence of six correlations in river Shimsha, five in river Suvarnavathy, three in river Cauvery, and two each in river Kapila and river Arkavathy. Negative SGR were recorded on thirteen occasions in river Cauvery followed by eleven in river Shimsha, nine in river Suvarnavathy, seven in river Arkavathy and five in river Kapila, out of fifty SGR determinations. This negative SGR were a result of decrease in the observed bacterial cell counts after 48 h incubation from that of 0 h count. The probable reason for such negative growth rate and dependency of SGR of bacterioplankton and environmental variables has been discussed.     

Dynamic evaluation of a regional air quality model: Assessing the emissions-induced weekly ozone cycle

Air quality models are used to predict changes in pollutant concentrations resulting from envisioned emission control policies. Recognizing the need to assess the credibility of air quality models in a policy-relevant context, we perform a dynamic evaluation of the Community Multiscale Air Quality (CMAQ) modeling system for the “weekend ozone effect” to determine if observed changes in ozone due to weekday-to-weekend (WDWE) reductions in precursor emissions can be accurately simulated. The weekend ozone effect offers a unique opportunity for dynamic evaluation, as it is a widely documented phenomenon that has persisted since the 1970s. In many urban areas of the Unites States, higher ozone has been observed on weekends than weekdays, despite dramatically reduced emissions of ozone precursors (nitrogen oxides [NO_x] and volatile organic compounds [VOCs]) on weekends. More recent measurements, however, suggest shifts in the spatial extent or reductions in WDWE ozone differences. Using 18 years (1988–2005) of observed and modeled ozone and temperature data across the northeastern United States, we re-examine the long-term trends in the weekend effect and confounding factors that may be complicating the interpretation of this trend and explore whether CMAQ can replicate the temporal features of the observed weekend effect. The amplitudes of the weekly ozone cycle have decreased during the 18-year period in our study domain, but the year-to-year variability in weekend minus weekday (WEWD) ozone amplitudes is quite large. Inter-annual variability in meteorology appears to influence WEWD differences in ozone, as well as WEWD differences in VOC and NO_x emissions. Because of the large inter-annual variability, modeling strategies using a single episode lasting a few days or a few episodes in a given year may not capture the WEWD signal that exists over longer time periods. The CMAQ model showed skill in predicting the absolute values of ozone concentrations during the daytime. However, early morning NO_x concentrations were underestimated and ozone levels were overestimated. Also, the modeled response of ozone to WEWD differences in emissions was somewhat less than that observed. This study reveals that model performance may be improved by (1) properly estimating mobile source NO_x emissions and their temporal distributions, especially for diesel vehicles; (2) reducing the grid cell size in the lowest layer of CMAQ; and, (3) using time-dependent and more realistic boundary conditions for the CMAQ simulations.     

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

ABSTRACT

Bench-scale and full-scale investigations of waste stabilization and volume reduction were conducted using spiked soil and ash wastes containing heavy metals such as Cd, Cr, Pb, Ni, and Hg. The waste streams were stabilized and solidified using chemically bonded phosphate ceramic (CBPC) binder, and then compacted by either uniaxial or harmonic press for volume reduction. The physical properties of the final waste forms were determined by measuring volume reduction, density, porosity, and compressive strength. The leachability of heavy metals in the final waste forms was determined by a toxicity characteristic leaching procedure (TCLP) test and a 90-day immersion test (ANS 16.1). The structural composition and nature of waste forms were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.

CBPC binder and compaction can achieve 80-wt % waste loading and 39-47% reduction in waste volume. Compressive strength of final waste forms ranged from 1500 to 2000 psi. TCLP testing of waste forms showed that all heavy metals except Hg passed the TCLP limits using the phosphate-based binder. When Na₂S was added to the binder, the waste forms also passed TCLP limits for Hg. Long-term leachability resistance of the final waste forms was achieved for all metals in both soil and ash wastes, and the leachability index was ~14. XRD patterns of waste forms indicated vermiculite in the ash waste was chemically incorporated into the CBPC matrix. SEM showed that waste forms are layered when compacted by uniaxial press and are homogeneous when compacted by harmonic press.     

Washing of Marine Coastal Sand in a Batch Reactor: Sorption and Desorption of BTEX

ABSTRACT

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_sa_s) and desorption (K_da_d) were estimated.This was achieved by minimization of errors while using the sorption coefficients (K_p) 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_ga_g) were estimated for BTEX. In these exercises of minimization of errors, comparable cumulative errors were obtained from the use of K_p values derived from experimental isotherms and QSARs.     

HSE项目管理体系中环境保护专业的作用

在对比国内建设项目环保管理体系和HSE环保管理体系的基础上，总结了PMC项目环保管理工作的经验，对HSE项目管理运作模式中环保专业的职能和作用进行了一定程度的探讨。     

Biodiesel blends: a comprehensive systematic review on various constraints

Environmental Science and Pollution Research - Biodiesel is a renewable, clean-burning diesel replacement that can be used in existing diesel engines without modification. Biodiesel is among the...     

地方生产安全应急救援体系的建立

1 时代的呼唤:建立地方生产安全应急救援体系势在必行、迫在眉睫 当前我国安全生产形势严峻,各类事故死亡人数居高不下,重特大事故不断发生,给国家经济和人民生命财产造成了重大损失.深刻反思,因生产安全事故造成重大伤亡除了事故频发外,还有一个重要原因,就是应急救援体系特别是地方生产安全应急救援体系尚未建立或不够完善,致使事故发生后不能快速有效地组织救援,造成事故扩大、伤亡人员增加的严重后果.目前在生产安全事故应急救援方面主要存在四个方面的问题:     

天然气输送管道泄漏事故危害定量分析

针对某市天然气利用工程中高压输送管道可能发生的天然气泄漏的危险性进行分析 ,求出了其最大的泄漏流量。通过高斯扩散模式定量计算在大气为中性条件下 ,天然气在大气中的轴向、径向和切向的扩散距离 ,从而计算出该天然气 -空气混合云团的体积。对该体积预混云团的火灾危害进行评估 ,计算形成火球的参数 ,用热辐射剂量准则计算其伤害半径。对该预混云团可能产生的爆轰后果 ,采用超压准则计算其对人员和建筑物的伤害半径。并用热辐射强度准则对可能产生稳态燃烧进行了危害半径的计算     

Analysis of Toxic Air Contaminant Data Containing Concentrations Below the Limit of Detection

Air quality data often contain several observations reported only as below the analytical limit of detection (LOD), resulting in “censored” data sets. Such censored and/or truncated data sets tend to complicate statistical analysis. This paper discusses various procedures for estimating mean concentration and Its 95 percent confidence bounds from air contaminant data sets which contain values that are reported as below the LOD, A quantitative approach for assessing the uncertainty Inherent In the estimated mean concentration due to (a) presence of values below the LOD In the data set, and (b) natural variability of atmospheric concentration data, is described. The utility of this approach In the analysis and interpretation of ambient pollutant concentration data Is demonstrated for both hypothetical and observed singly-censored data sets, and for a multiply-censored, multi-pollutant observed concentration data set. The methodologies discussed here should be particularly useful In verifying compliance with environmental regulations, and In estimating the risks associated with long-term exposure of populations to toxic air contaminants and assessing the uncertainty associated with these estimates.