PAH and soot emissions from burning components of medical waste: examination/surgical gloves and cotton pads

This is a laboratory investigation on the emissions from batch combustion of representative infectious ("red bag") medical waste components, such as medical examination latex gloves and sterile cotton pads. Plastics and cloth account for the majority of the red bag wastes by mass and, certainly, by volume. An electrically heated, horizontal muffle furnace was used for batch combustion of small quantities of shredded fuels (0.5-1.5 g) at a gas temperature of approximately 1000 degrees C. The residence time of the post-combustion gases in the furnace was approximately 1 s. At the exit of the furnace, the following emissions were measured: CO, CO2, NOx, particulates and polynuclear aromatic compounds (PACs). The first three gaseous emissions were measured with continuous gas analyzers. Soot and PAC emissions were simultaneously measured by passing the furnace effluent through a filter (to collect condensed-phase PACs) and a bed of XAD-4 adsorbent (to capture gaseous-phase PACs). Analysis involved soxhlet extraction, followed by gas chromatography-mass spectrometry (GC-MS). Results were contrasted with previously measured emissions from batch combustion of pulverized coal and tire-derived fuel (TDF) under similar conditions. Results showed that the particulate soot) and cumulative PAC emissions from batch combustion of latex gloves were more than an order of magnitude higher than those from cotton pads. The following values are indicative of the relative trends (but not necessarily absolute values) in emission yields: 26% of the mass of the latex was converted to soot, 11% of which was condensed PAC. Only 2% of the mass of cotton pads was converted to soot, and only 3% of the weight of that soot was condensed PAC. The PAC yields from latex were comparable to those from TDF. The PAC yields from cotton were higher than those from coal. A notable exception to this trend was that the three-ring gas-phase PAC yields from cotton were more significant than those from latex. Emission yields of CO and CO2 from batch combustion of cotton were, respectively, comparable and higher than those from latex, despite the fact that the carbon content of cotton was half that of latex. This is indicative of the more effective combustion of cotton. Nearly all of the mass of carbon of cotton gasified to CO and CO2 while only small fractions of the carbon in latex were converted to CO2 and CO (20% and 10%, respectively). Yields of NOx from batch combustions of latex and cotton accounted for 15% and 12%, respectively, of the mass of fuel nitrogen indicating that more fuel nitrogen was converted to NOx in the former case, possibly due to higher flame temperatures. No SO2 emissions were detected, indicating that during the fuel-rich combustion of latex, its sulfur content was converted to other compounds (such as H2S) or remained in the soot.     

An intelligent emissions controller for fuel lean gas reburn in coal-fired power plants

The application of artificial intelligence techniques for performance optimization of the fuel lean gas reburn (FLGR) system is investigated. A multilayer, feedforward artificial neural network is applied to model static nonlinear relationships between the distribution of injected natural gas into the upper region of the furnace of a coal-fired boiler and the corresponding oxides of nitrogen (NOx) emissions exiting the furnace. Based on this model, optimal distributions of injected gas are determined such that the largest NOx reduction is achieved for each value of total injected gas. This optimization is accomplished through the development of a new optimization method based on neural networks. This new optimal control algorithm, which can be used as an alternative generic tool for solving multidimensional nonlinear constrained optimization problems, is described and its results are successfully validated against an off-the-shelf tool for solving mathematical programming problems. Encouraging results obtained using plant data from one of Commonwealth Edison's coal-fired electric power plants demonstrate the feasibility of the overall approach. Preliminary results show that the use of this intelligent controller will also enable the determination of the most cost-effective operating conditions of the FLGR system by considering, along with the optimal distribution of the injected gas, the cost differential between natural gas and coal and the open-market price of NOx emission credits. Further study, however, is necessary, including the construction of a more comprehensive database, needed to develop high-fidelity process models and to add carbon monoxide (CO) emissions to the model of the gas reburn system.     

Heavy metal pollution and forest health in the Ukrainian Carpathians

The Ukrainian Carpathians are characterized by high air pollution caused by emissions from numerous industries. We have been monitoring the state of forests in this region since 1989. The highest levels of tree defoliation (>30%) are found close to industrial emission sources and in the upper mountain forests of the Ivano-Frankivsk and Chernivtsi regions. This is caused by a combination of strong anthropogenic influences (pollution, illegal uses, recreation) as well as poor site and climatic conditions. In the Ivano-Frankivsk region, Cd and Mo accumulate in forest soils; Cr, Mo and Zn soil concentrations are higher than their limit levels; and Pb concentrations exceed toxic levels close to industrial areas (10% of the region territory). Local background levels of heavy metals are greatly exceeded in snow close to industrial regions. Analysis of correlation matrices shows that the chemical elements Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn occur at pollution levels in natural ecosystems in the Ukrainian Carpathians. Maximum concentrations of toxic elements occur in the oak forest zone; the most industrially developed area of the region. Toxic heavy metals in the Ukrainian Carpathians forests enter with precipitation and dustfall, then become fixed in soil and accumulate in leaves, needles of vascular plants and mosses. Concentrations of these metals decrease with altitude: highest in the oak forests, less in beech, and lowest in the spruce forest zones. However, some chemical elements have the highest concentrations in spruce forests; V in needles, As in snow, and Ba and Al in soils.     

Biodegradation of trifluralin in Harran soil

Degradation of trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was investigated in soils taken from three different locations at Harran region of Turkey under laboratory conditions. Surface (0-10 cm) soils, which were taken from a pesticide untreated field Gürgelen, Harran-1 and Ikizce regions in the Harran Plain. were incubated in biometer flasks for 350 days at 25 degrees C. Ring-UL-14C-trifluralin was applied at the rate of 2 microg g(-1) with 78.7 kBq radioactivity per 100 g soil flask. Evolved (14)CO2 was monitored in KOH traps throughout the experiment. Periodically, soil sub-samples were removed and extracted by supercritical fluid extraction (SFE). Unextractable soil-bound 14C residues were determined by combustion. During the 350 days incubation period 6.6, 5.4, and 3.3/' of the applied radiocarbon was evolved as (14)CO2 from the Harran-1, Gürgelen, and Ikizce soil, respectively. At the end of 350 days the SFE-extractable and bound 14C-trifluralin residues were 39.0 and 29.2% of the initially applied herbicide in Gürgelen soil. The corresponding values for Harran-1 and Ikizce soils were 36.2, 28.4% and 41.6, 18.5% respectively.     

印染废水生物强化处理技术研究进展

印染废水是国内外公认的难处理的工业废水之一 ,活性污泥法是目前最常用的处理方法 ,但还存在诸多问题。在分析中 ,主要从生物强化技术、固定化微生物技术和微生物活性增加技术等方面 ,总结了废水生物处理技术强化研究进展 ,并讨论了今后的研究方向。     

城市生活污水厌氧生物处理发展现状

回顾了国内外污水厌氧生物处理工艺的发展情况,着重分析了中国城市污水的特点以及厌氧生物处理工艺在城市生活污水处理中的应用情况。     

Persistence of residues in water and sediment of a fresh-water lake after surface application of technical chlordane

A fresh-water lake, free from detectable pesticide residues before this study, was treated with a commercial formulation of technical chlordane. Water and sediment samples were analysed for chlordane residues 7, 24, 52, 279. and 421 days after treatment. Residues moved rapidly from the water to the lake bottom, supporting earlier results of a laboratory study with other organochlorines. In water, alpha- and gamma-chlordane concentrations remained proportional to total chlordane concentrations, as determined by total-peak area measurements of gas-liquid chromatogrammes. But in bottom sediments, alpha- and gamma-chlordane were more persistent than other constituents of technical chlordane, supporting recent evidence that quantification of technical chlordane residues on the basis of gamma-chlordane quantification only (or that of alpha- and gamma-chlordane only), can lead to incorrect results and that this method, although simple and fast, should no longer be recommended.     

我国生态环境保护重大工程项目管理制度现状及存在的问题

生态环境重大工程项目是中国生态环境保护规划实施的重要抓手,工程实施与管理的科学性和可行性是提高资金使用效率和确保项目发挥环境效益的关键,因此,系统构建生态环境保护重大工程项目管理制度具有必要性和现实意义。结合国家现行政策,在实际调研的基础上,梳理了现有生态环境保护重大工程项目管理制度,分析了地方重大工程项目管理现状,识别了目前生态环境保护重大工程项目管理的存在问题,据此提出了完善生态环境保护重大工程项目制度的建议框架,以期为实现新时代生态环境保护目标提供支撑。     

基于三角随机模拟和ArcGIS的河流水环境健康风险评价模型

基于河流水环境系统中随机性、模糊性等多种不确定性共存或交叉存在的特性,将三角模糊数与随机模拟方法相耦合,构建了三角随机模拟模型,并将其应用到湘江(长沙段)的健康风险评价中。通过将各参数浓度进行三角模糊化和随机模拟,结果表明,各断面污染物造成的健康风险的变化趋势,总体沿湘江上游至下游逐步降低,表现为昭山 > 猴子石 > 五一桥 > 橘子洲 > 乔口 > 三汊矶,且昭山、三汊矶断面和乔口断面均有恶化趋势。相对于常规的确定性方法,本模型能够得出评价区域健康风险的可能值区间及其相应的概率水平等定量信息,更加客观、全面地表征评价区域的风险状态及其空间分布差异,为决策者提供更多有用的信息。