The Microscopic Identification of Atmospheric Particulates

Lime has become the world’s leading reagent for use in the treatment of both water and air pollution and, after sulfuric acid, is the No. 2 basic chemical in commercial use. As a result, the production capacities of the manufacturing plants are being rapidly expanded to meet the increasing demand for liming materials. This paper describes the achievements of the lime industry in developing methods of handling and controlling the various finely divided products which they produce. An extensive survey provides useful data on the availability and performance of many of the control devices that are currently in use, and an analysis is made of the operating efficiencies and costs of this equipment. The environmental control programs which are currently underway in this industry are described and an evaluation is made of these programs. The ultimate goals that are believed to be attainable are presented from the standpoint of emission control from individual processes as well as from operating plant complexes. While the paper deals primarily with practical operating and engineering aspects of the subject, some information is also included on methods of tests and the monitoring systems that are in use.     

SEJF多功能水处理器及其在印染废水处理中的应用

SEJF多功能水处理器是将物化处理与生化处理有机结合在一起的水处理设备,可在一器内完成均质、曝气、混合、反应和固液分离数种功能.采用SEJF多功能水处理器工艺对印染废水进行处理,工程实践表明,该水处理器工艺具有高效、节能、节地、节资等优点,而且处理效果稳定,运行费用低,操作管理方便,灵活性和适应性强.     

High-volume Impactor for Sampling Fine and Coarse Particles

Final design, calibration, and field testing have been completed for a new 1.13 m³/min (40 cfm) High-volume Virtual Impactor (HVVI). Field tests have demonstrated that the new classifier/collector works well as an accessory to the existing PM10 Size Selective Inlet high-volume samplers. The HVVI provides two fractions of PM10 mass, both of which are collected by filtration. The fine fraction (0-2.5 μm aero. dia.) Is collected on the standard 20.3 × 25.4 cm (8- × 10-in) high-volume filter; the coarse fraction (2.5-10 μm aero. dia.) is collected on a 5.1 × 15.2 cm (2- × 6-in) filter. Coarse flow through the receiver tubes is limited to 0.057 m³/min (2 cfm), 5 percent of the total flow.

The operating pressure drop across the HVVI stages Is sufficiently high to make changes In pressure across the collection filters Insignificant. The HVVI filter holder assembly facilitates loading/ unloading samples in the laboratory, thus eliminating damage due to handling filters in the field. Size separation characteristics of the HVVI agree well with those for the 16.7 L/min commercially available dichotomous sampler with the 50 percent effectiveness (cut-point) occurring at 2.5 μm. Applying laboratory-determined particle losses to the typical ambient particle mass size distribution described In Federal Register 49, 40 CFR, Part 53, Table D-3, the HVVI fine fraction total mass loss is less than 0.8 percent for liquid particles and less than 0.1 percent for solid particles; coarse fraction total mass loss is less than 2.5 percent for liquid particles, and less than 0.2 percent for solid particles.     

Chapter one: exposure measurements

Determining human exposure to suspended particulate concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these are typically measured with time-integrated samples on filters that are later submitted to laboratory analyses. This requires substantial sample handling, quality assurance, and data reduction. Newer technologies are being developed that allow in-situ, time-resolved measurements for mass, carbon, sulfate, nitrate, particle size, and other variables. These are large measurement systems that are more suitable for fixed monitoring sites than for personal applications. Human exposure studies need to be designed to accomplish specific objectives rather than to serve too many purposes. Resources need to be divided among study design, field sampling, laboratory analysis, quality assurance, data management, and data analysis phases. Many exposure projects allocated too little to the non-measurement activities.     

环境监测实验室内质量控制体系的设想

环境监测实验室质量控制足环境监测质量保汪的蘑要组成部分。山于实验室内质量控制工作量大，质控工作往往流于形式。因此，有必要建立一套完整又便捷的实验室内质量控制体系，在质控质量上发挥重要作用。对体系建立前提条件和体系建立的，思路进行了阐述。对体系设计基础——计算机网络技术的运用。实验室内质量评价高效、便捷的数字化应用平台的建口进行了设想。     

Organosulfates from glycolaldehyde in aqueous aerosols and clouds: Laboratory studies

Secondary organic aerosol (SOA) formation is enhanced on acidic seed particles; SOA also forms during cloud processing reactions where acidic sulfate is prevalent. Recently several studies have focused on the identification of organosulfates in atmospheric aerosols or smog chamber experiments, and upon the mechanism of formation for these products. We identify several organosulfate products formed during the laboratory OH radical oxidation of dilute aqueous glycolaldehyde in the presence of sulfuric acid. We propose a radical–radical reaction mechanism as being consistent with formation of these products under our experimental conditions. Using a kinetics model we estimate that organosulfates account for less than 1% of organic matter formed from these precursors during cloud processing. However, in wet acidic aerosols, where precursors are highly concentrated and acidic sulfate makes up close to half of the aerosol mass, this radical–radical reaction could account for significant organosulfate production.     

Multi-substrate, multi-option groundwater transport model

A user friendly, finite-difference groundwater transport model, called “Multi-substrate, Multi-option Groundwater Transport Model (MMGTM)”, has been developed to afford users several options in defining a transport sequence. In addition to advective-dispersive transport, the model incorporates a variety of adsorption and biological decay mechanisms. Adsorption can be simulated for linear, Langmuir, or Freundlich isotherms coupled with equilibrium or non-equilibrium mass transfer. Biological decay can be simulated for first-order or Monod-type approaches, and can be linked to oxygen consumption and transport. Aqueous and sorbed phase decay can be simulated.Further, the transport of two substrates and oxygen can be simulated concurrently and the interaction between them can be described as competitive, diauxic-like or simultaneous. The growth of biomass and its effect as an adsorbent can also be simulated by means of a stoichiometric yield coefficient and a biomass/adsorbent conversion factor. Continuous or pulse input of solute in conjunction with either constant-mass-flux or constant-concentration boundaries can be selected. Menu screens allow the user to configure each problem while parameters can be input individually or called from a separate data file. The input data can be viewed, modified or saved before simulation. Output is visually displayed of the screen as breakthrough and profile curves, while also being saved to an ASCII file on a disk for subsequent processing.     

Quantitative analysis of environmental factors in differential weighing of blank Teflon filters

Mass differences less than 100 microg must be correctly measured in gravimetric analysis of particles collected on filters. Even small variations in mass measurement may contribute significant errors to calculated concentrations. In addition to the collected particles, a number of other factors affect the observed mass difference between the measurements before and after sampling. The most often controlled of these factors are static charge, temperature, and humidity. Using 951 laboratory blank filter weights, we have statistically analyzed these and other factors that affect the observed filter weight. Some of these are controllable or correctable; others are not and enter into the final results as errors. The standard deviation of differential blank filter weighing after applying all corrections was 2.7 microg. The most important correctable factors are air buoyancy variation and filter storage time. When weighing blank Teflon filters at relative humidity < 50%, these are an order of magnitude more important than weighing-room humidity. Using field blank filters in each weighing batch could control these three factors but also doubles the errors caused by balance random variation and filter handling contamination, because four weighing measurements and the handling of two filters are needed to obtain one corrected differential mass result.     

An analytical solution for estimating percolation rate by fitting temperature profiles in the vadose zone

We present a simple analytical solution for one-dimensional steady heat transfer with convection and conduction through a multilayer system such as a vadose zone. We assume that each layer is homogeneous and has a constant thermal diffusivity. The mass/heat flow direction is perpendicular to the layers, and the mass flow rate is a constant. The analytical solution presented in this study also assumes constant known temperatures at the two boundaries of the system. Although the analytical solution gives the temperature as a function of a few parameters, we focus on the inverse application to estimate the percolation rate in a vadose zone. Example applications have shown that with reliable field observation data, the solution can be used to determine the percolation rate to high degree of accuracy (e.g., to mm/year). In some other cases, the solution may also be helpful in characterizing potential lateral flow along layer divides.     

Time-resolved measurements of aerosol elemental concentrations in indoor working environments

We have measured the elemental concentrations in aerosols with a 2-h time resolution in two different types of working environment: a chemistry laboratory dealing with the processing of advanced nanoparticulate materials and a medium-sized machine workshop. Non-stop 10-day and 12-day samplings were performed at each location in order to determine the concentration trends during the non-working/working and weekday/weekend periods. Supplementary measurements of PM10 aerosols with a 2-day sample collection time were performed with a standard Gent PM10 sampler to compare the elemental concentrations with the time-averaged concentrations detected by the 2D step-sampler. The concentrations were determined a posteriori by analyzing the x-ray spectra of aerosol samples emitted after 3-MeV proton bombardment. The PM10 samples collected in the chemistry laboratory were additionally inspected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) to determine the chemical compositions of the individual particles. In the workshop, a total PM10 mass sampling was performed simultaneously with a minute resolution to compare the signal with typical outdoor PM10 concentration levels. A factor analysis of the time-resolved dataset points to six and eight factors in the chemistry laboratory and the machine workshop, respectively. These factors describe most of the data variance, and their composition in terms of different elements can be related to specific indoor activities and conditions. We were able to demonstrate that the elemental concentration sampling with hourly resolution is an excellent tool for studying the indoor air pollution. While sampling the total PM10 mass concentration with a minute resolution may lack the potential to identify the emission sources in a “noisy” environment, the time averaging on a day time scale is too coarse to cope with the working dynamics, even if elemental sensitivity is an option.     

Citizen Complaints of Air Pollution In Northeastern Illinois

In 1964, as part of the Northeastern Illinois Metropolitan Planning Commission's Air Resource Management Study, an examination was made of citizen complaints of air pollution registered with air pollution control agencies representing the City of Chicago, outlying Cook County, and the State of Illinois. The complaint files of the City of Chicago were found to contain the addresses of some 9500 air pollution sources specified by complainants in complaints covering the time period from approximately 1954 to 1964. A statistical sample of these sources showed more than 70% to be of a nonindustrial nature, with domestic fuel burning or incineration by neighbors most often specified. There were 1119 industrial process source snamed in the Chicago files; 588 nonmanufacturing and 531 manufacturing. Fabricated metal industries, primary metal industries, chemical manufacturers, and food processing plants were cited more often than other industrial categories. Complaint sources named in complaints filed by citizens with the State of Illinois, and with Cook County, differed with those of Chicago in that industrial sources were specified more often than nonindustrial ones. The reason for this is believed to lie in the reduced residential densities and the relatively great use of pollution-free fuels in the metropolitan area outside of the City of Chicago.     

Sulfur hexafluoride (SF6): global environmental effects and toxic byproduct formation

This work provides information concerning possible global environmental implications and personnel safety aspects that should be considered during the commercial uses of sulfur hexafluoride (SF6). SF6 is an anthropogenically produced compound, mainly used as a gaseous dielectric in gas insulated switchgear power installations. It is a potent greenhouse gas with a high global warming potential, and its concentration in the earth atmosphere is rapidly increasing. During its working cycle, SF6 decomposes under electrical stress, forming toxic byproducts that are a health threat for working personnel in the event of exposure. Several precautions are recommended to avoid personnel exposure to toxic byproducts: oxyfluoride levels or other byproduct concentrations in the operating gas matrix should be traced to predetermine the overall gas toxicity; contaminants should be systematically considered during maintenance, chamber evacuation and system opening process; small SF6 quantities leaking into air or stagnated pollutant concentrations in the operating field should be analyzed and compared to the threshold limit values and permissible exposure levels. New system design rules (i.e., hermetically sealed gas compartments, gas recycling or disposal in the field area) and different handling policies--both during maintenance and final disposal--now should be considered globally to provide for environmental and personnel safety.     

PM2.5 speciation trends network: evaluation of whole-system uncertainties using data from sites with collocated samplers

The objectives of this paper are to contrast the relative variability of replicate laboratory measurements of selected chemical components of fine particulate matter (PM) with total variability from collocated measurements and to compare the magnitudes of the uncertainties determined from collocated sampler data with those currently being provided to U.S. Environmental Protection Agency (EPA)'s Air Quality System (AQS) database by RTI International (RTI). Pointwise uncertainty values are needed for modeling and data analysis and should include all the random errors affecting each data point. Total uncertainty can be decomposed into two primary components: analytical measurement uncertainty and sampling uncertainty. Analytical measurement uncertainties are relatively easy to calculate from routine quality control (QC) data. Sampling uncertainties, on the other hand, are comparatively difficult to measure. In this paper, the authors describe data from collocated samplers to provide a snapshot of whole-system uncertainty for several important chemical species. The components of uncertainty were evaluated for key species from each of the analytical methods employed by the PM2.5 Speciation Trends Network (STN) program: gravimetry, ion chromatography (IC), X-ray fluorescence (XRF), and thermal-optical analysis for organic carbon and elemental carbon. The results show that the laboratory measurement uncertainties are typically very small compared with uncertainties calculated from the differences between samples collected from collocated samplers. These differences are attributable to the "field" components uncertainty, which may include contamination and/or losses during shipping, handling, and sampling, as well as other distortions of the concentration level due to flow and sample volume variations. Uncertainties calculated from the collocation results were found to be generally similar to the uncertainties currently being loaded into EPA's AQS system, with some exceptions described below.     

Filtration Properties of Fly Ash from Fluidized Bed Combustion

Some of the features of the fluidized-bed combustion (FBC) process have a direct bearing on the particulate properties that most strongly influence filtering pressure drop. A laboratory program was conducted to experimentally determine the relative pressure drop characteristics of ashes from the TVA-EPRI 20-MW bubbling bed, atmospheric pressure FBC (AFBC) pilot plant and six pulverized-coal combustion (PC) units. The combined influences of measured particle and dust cake properties on filtering pressure drop were estimated with existing filtration theories. These theories predict a higher pressure drop for a dust cake produced with the AFBC ash than for one consisting of any of the PC ashes. Laboratory measurements were made of the flow resistance of idealized, simulated dust cakes to confirm these predictions. Field operating data from the fabric filters collecting some of the tested ashes were available to validate the laboratory results. The laboratory and field data show relatively good agreement. The AFBC ash must be treated as a special case for fabric filters, and careful selection of cleaning method and fabric must be made to minimize the inherently high pressure drop characteristics of this ash.     

Development and evaluation of a continuous coarse (PM10-PM2.5) particle monitor

In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 microm) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating principle of the monitor is based on enriching CM concentrations by a factor of approximately 25 by means of a 2.5-microm cut point round nozzle virtual impactor while maintaining fine mass (FM)--that is, the mass of PM2.5 at ambient concentrations. The aerosol mixture is subsequently drawn through a standard tapered element oscillating microbalance (TEOM), the response of which is dominated by the contributions of the CM, due to concentration enrichment. Findings from the field study ascertain that a TEOM coupled with a PM10 inlet followed by a 2.5-microm cut point round nozzle virtual impactor can be used successfully for continuous CM concentration measurements. The average concentration-enriched CM concentrations measured by the TEOM were 26-27 times higher than those measured by the time-integrated PM10 samplers [the micro-orifice uniform deposit impactor (MOUDI) and the Partisol] and were highly correlated. CM concentrations measured by the concentration-enriched TEOM were independent of the ambient FM-to-CM concentration ratio, due to the decrease in ambient coarse particle mass median diameter with an increasing FM-to-CM concentration ratio. Finally, our results illustrate one of the main problems associated with the use of real impactors to sample particles at relative humidity (RH) values less than 40%. While PM10 concentrations obtained by means of the MOUDI and Partisol were in excellent agreement, CM concentrations measured by the MOUDI were low by 20%, and FM concentrations were high by a factor of 5, together suggesting particle bounce at low RH.     

High Temperature,High Pressure Electrostatic Precipitation

This paper presents the results of work conducted by Research-Cottrell under EPA contract 68-02-2104. The feasibility of electrostatic precipitation at temperatures and pressures varying from ambient condition to 1366°K and 3550 kPa, respectively, has been demonstrated in a laboratory wire-pipe electrode system. Stable corona discharges are obtained at all temperatures subject to appropriate choices of electrode dimension, polarity, and pressure. Current-voltage characteristics are reported for dry air, a simulated combustion gas, and a substitute fuel gas. The effects of temperature, pressure, electrode geometry and polarity on sparkover voltage, corona-starting voltage, and current are evaluated. A precipitator performance model is included to incorporate this data into a high temperature, high pressure precipitator design. This model has been evaluated for an electrostatic (HTHP) precipitator following a pressurized fluidized bed combustor at 1089 K and 920 kPa. It is recommended that prototype HTHP electrostatic precipitators be applied to pilot coal gasifiers and fluidized bed combustors to obtain detailed design data and to verify the accuracy of the performance model under actual operating conditions.     

Development of a database for chemical mechanism assignments for volatile organic emissions

The development of a database for making model species assignments when preparing total organic gas (TOG) emissions input for atmospheric models is described. This database currently has assignments of model species for 12 different gas-phase chemical mechanisms for over 1700 chemical compounds and covers over 3000 chemical categories used in five different anthropogenic TOG profile databases or output by two different biogenic emissions models. This involved developing a unified chemical classification system, assigning compounds to mixtures, assigning model species for the mechanisms to the compounds, and making assignments for unknown, unassigned, and nonvolatile mass. The comprehensiveness of the assignments, the contributions of various types of speciation categories to current profile and total emissions data, inconsistencies with existing undocumented model species assignments, and remaining speciation issues and areas of needed work are also discussed. The use of the system to prepare input for SMOKE, the Speciation Tool, and for biogenic models is described in the supplementary materials. The database, associated programs and files, and a users manual are available online at http://www.cert.ucr.edu/~carter/emitdb.

Implications: Assigning air quality model species to the hundreds of emitted chemicals is a necessary link between emissions data and modeling effects of emissions on air quality. This is not easy and makes it difficult to implement new and more chemically detailed mechanisms in models. If done incorrectly, it is similar to errors in emissions speciation or the chemical mechanism used. Nevertheless, making such assignments is often an afterthought in chemical mechanism development and emissions processing, and existing assignments are usually undocumented and have errors and inconsistencies. This work is designed to address some of these problems.     

Effect of thermal processing on the characteristics of incineration fly ash

This work investigated the possibilities of immobilizing incineration fly ash by applying different processing methods. Direct sintering of fly ash at 1050 degrees C produced material with increased resistance to leaching; however, the high content of halides prevented the achievement of appropriate strength. Fly ash melting and casting into metallic moulds resulted in the formation of glass with good chemical resistivity and mechanical properties, which were further improved by devitrification, and the formation of glass-ceramics. The most successful combination of strength and resistance to leaching was obtained by a process consisting of fly ash melting, by pouring the melt into water, then grinding, and sintering without additives at 850-950 degrees C. In this way, a material was produced that cannot only be landfilled as a stabilised and non-reactive waste in landfills for non-hazardous wastes, but can also be utilized as a valuable material for manufacturing useful products. This article provided valuable results for policy-makers in Slovenia, about the handling fly ash from incineration plants. Implications: Fly ash from an incineration plant was thermally treated using several processing routes. Ash-melting, by pouring the melt into water and sintering, produced glass-ceramics having an optimal combination of strength and resistance to leaching that can find applications as useful products. These results provide important data for policy makers in Slovenia regarding the building of incineration plants, and handling the solid-waste products, especially fly ash.     

Prediction of some in situ tracer tests with sorbing tracers using independent data

Some recent converging tracer tests with sorbing tracers at the Asp? Hard Rock Laboratory in Sweden, the TRUE tests, have been predicted using only laboratory data and hydraulic data from borehole measurements. No model parameters were adjusted to obtain a better fit with the experiments. The independent data were fracture frequency and transmissivity data obtained in the field and laboratory data on sorption and matrix diffusion. Transmissivity measurements in five boreholes in the rock volume containing the region surrounding the injection and collection points show that there is a high frequency of water conducting fractures. Of 162 packed off sections with 0.5 m packer distances, 112 were found to have a transmissivity above the detection limit. The specific flow-wetted surface (FWS) of the rock mass could be estimated from these data. The transmissivities were found to be reasonably well described by a lognormal distribution. Laboratory data on diffusion and sorption properties together with the hydraulic data were used to "predict" the residence time distribution (RTD) of the sorbing tracers. The results were compared with the experimental breakthrough curves. In these experiments, the water residence time is very small compared to the residence time of the sorbing tracers due to their diffusion and sorption within the rock matrix. We thus could neglect the influence of the water residence time in our predictions. Therefore, no information on water residence times or on "dispersion" was needed. The dispersion of the sorbing tracers is caused by the different sorbing tracer residence times in different pathways. The sorbing tracer residence time is determined by the ratio of flowrate to the flow-wetted surface in the different pathways and not by the water residence time. Assuming a three-dimensional flow pattern and using the observed fracture frequency and flowrate distribution, breakthrough curves for three strongly sorbing tracers were predicted. Only the laboratory data, the transmissivity measurements and the pumping flowrate were used in the predictions. No information on the water residence time as obtained by the nonsorbing tracers was used. The predictions were surprisingly accurate.