Formation, release and control of dioxins in cement kilns

Co-processing of hazardous wastes in cement kilns have for decades been thought to cause increased emissions of PCDD/PCDFs--a perception that has been evaluated in this study. Hundreds of PCDD/PCDF measurements conducted by the cement industry and others in the last few years, on emissions and solid materials, as well as recent test burns with hazardous wastes in developing countries do not support this perception. Newer data has been compared with older literature data and shows in particular that many emission factors have to be reconsidered. Early emission factors for cement kilns co-processing hazardous waste, which are still used in inventories, are shown to be too high compared with actual measurements. Less than 10 years ago it was believed that the cement industry was the main contributor of PCDD/PCDFs to air; data collected in this study indicates however that the industry contributes with less than 1% of total emissions to air. The Stockholm Convention on POPs presently ratified by 144 parties, classifies cement kilns co-processing hazardous waste as a source category having the potential for comparatively high formation and release of PCDD/PCDFs. This classification is based on early investigations from the 1980s and 1990s where kilns co-processing hazardous waste had higher emissions compared to those that did not burn hazardous waste. However, the testing of these kilns was often done under worst case scenario conditions known to favour PCDD/PCDF formation. More than 2000 PCDD/PCDF cement kiln measurements have been evaluated in this study, representing most production technologies and waste feeding scenarios. They generally indicate that most modern cement kilns co-processing waste today can meet an emission level of 0.1ngI-TEQ/m(3), when well managed and operated. In these cases, proper and responsible use of waste including organic hazardous waste to replace parts of the fossil fuel does not seem to increase formation of PCDD/PCDFs. Modern preheater/precalciner kilns generally seems to have lower emissions than older wet-process cement kilns. It seems that the main factors stimulating formation of PCDD/PCDFs is the availability of organics in the raw material and the temperature of the air pollution control device. Feeding of materials containing elevated concentrations of organics as part of raw-material-mix should therefore be avoided and the exhaust gases should be cooled down quickly in long wet and long dry cement kilns without preheating. PCDD/PCDFs could be detected in all types of solid samples analysed: raw meal, pellets and slurry; alternative raw materials as sand, chalk and different ashes; cement kiln dust, clinker and cement. The concentrations are however generally low, similar to soil and sediment.     

An Evaluation of Commercial Hazardous Waste Thermal Destruction Capacity

Thermal destruction capacity for commercial hazardous waste in the United States is examined to determine current and future capacity requirements. This study focuses on commercial incinerators and cement kilns burning conventional hazardous wastes. Aggregate maximum and available capacity estimates are derived using the most recent information. On a national basis, available capacity far exceeds present demand. On a regional basis, capacity appears sufficient with the exception of the California area. However, this shortfall appears insignificant given the overall capacity situation. While incineration demand may increase for solids and sludges as a consequence of Land Ban disposal restrictions and other reasons, capacity for these wastes again appears sufficient to meet current and projected demands. Thus, arguments that additional commercial incineration capacity will be needed to accommodate an expected increase in incinerable hazardous waste cannot be supported by the available information. The analysis raises concerns about the determination of realistic capacity estimates, and the lack of interaction between the capacity assurance process that documents the need for capacity and state siting processes for new waste management facilities. The excess incineration capacity shown in this paper will contribute to the successful implementation of EPA’s goal to reduce national capacity.     

砒霜生产化工厂危险废物处置工程设计

通过对砒霜生产化工厂原场址废渣及污染场地调查的基础上,进行了处置方案比选及技术经济比较,确定了就地安全填埋的处置方案。根据区域性危险废物集中安全填埋场的设计经验,本工程采用先进的HDPE双层防渗的安全填埋方式,并设置了雨水分流系统、渗滤液收集系统、封场处理和填埋气体导排系统,整个场区布置合理,对周围环境的影响小,投资少,取得了良好的社会效益和环境效益,并对危险废物处理处置工程设计中应注意的问题提出了建议。     

安全土地填埋技术在我国的应用

沈阳市固体废物处置中心对工业危险废物采用了安全土地填埋技术 ,它的主要特点是安全、工艺简单、可操作性强。能够杜绝危险废物渗析液下渗污染地下水 ,同时又避免了危险废物污染环境卫生。本文主要以沈阳工业危险废物处置填埋场为例 ,介绍安全土地填埋的技术要求、设计要点等     

A Review of Treatment Alternatives for Wastes Containing Treatment Technologies For Hazardous Wastes: Part V

The Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act direct the Environmental Protection Agency to determine the available treatment technologies for a number of hazardous waste streams, including halogenated organics. If it is determined that existing technology and capacity is sufficient for the safe management of the designated halogenated organic wastes, these wastes will be prohibited from land disposal, effective July 8,1987. This article summarizes the general characteristics and treatment alternatives for this waste category.     

Conversion of chromium-containing solid wastes into value-added products through a plasma-assisted aluminothermic process

Chromium-containing solid wastes have been generated by chemical and leather/tanning industries, and the management and proper disposal of the same wastes have been challenging tasks. A significant fraction of these wastes contains chromium compounds with chromium present in the hexavalent (Cr⁺⁶) form, which is hazardous to human beings, animals, and ecosystems. Since these wastes are discarded largely without proper treatments, soil and groundwater get contaminated and they can cause several health issues to human beings. Conventional methods developed to convert hazardous Cr⁶⁺ to Cr³⁺/Cr metal either generate secondary toxic wastes and unwanted by-products and/or are time-consuming processes. In this work, a plasma-assisted aluminothermic process is developed to convert the toxic waste into non-toxic products. The waste was mixed with aluminium powder and subjected to transferred arc plasma treatment in a controlled air atmosphere. Chemical analysis and Cr leachability studies of the waste material prior to plasma treatment have shown that it is highly toxic. Analysis of the products obtained from the plasma treatment showed that Cr and Fe present in the waste could be recovered as a metallic mixture as well as oxide slag, which were found to be non-toxic. Easy separation of the metallic fraction and the slag from the treated product is one of the merits of this process. Besides converting chromium-containing toxic waste to non-toxic materials, the process is rapid and recovers the metals from the waste completely.

     

Immobilization of metal wastes by reaction with H2S in anoxic basins

Metal wastes are produced in large quantities by a number of industries. Their disposal in isolated waste deposits is certain to cause many subsequent problems, because every material will sooner or later return to the geochemical cycle. The sealing of disposal sites usually starts to leak, often within a short time after the disposal site has been filled. The contained heavy metals are leached from the waste deposit and will contaminate the soil and the groundwater. It is evident that storage as metal sulfides in a permanently anoxic environment is the only safe way to handle metal wastes. The world's largest anoxic basin, the Black Sea, can serve as a georeactor. The metal wastes are sustainably transformed into harmless and immobile solids. These are incorporated in the lifeless bottom muds, where they are stored for millions of years.     

Treatment Technologies For Hazardous Wastes: Part IV A Review of Alternative Treatment Processes for Metal Bearing Hazardous Waste Streams

The U.S. Congress and the U.S. Environmental Protection Agency believe that treatment and recovery techniques should be given maximum priority when considering methods for managing the nation's generated hazardous waste. A prohibition for the disposal of certain categories of hazardous wastes either directly onto or into the land without being treated to an accepted degree prior to such disposal practice has been promulgated.¹ Wastes containing toxic metals and cyanide complexes have been selected as a group to be restricted. Due to the high generation rate associated with this category, a large capacity of waste treatment processing will be required. Existing and emerging treatment alternatives which are or have the potential to be employed for waste treatment of metal bearing wastes are presented in this paper.     

Waste incineration in cement plants: constraints and development opportunities (a French-German comparison)

Is it possible to reconcile economic and ecological concerns? This article examines, through a French-German comparison, the case of obtaining a calorific value for wastes used as substitute fuels in cement kilns. On the one hand, this new strategy for obtaining needed inputs offers to the cement industry an economic opportunity for lowering production costs (the main determinant of competitivity in this sector). On the other hand, the controlled incineration of wastes allows the cement industry to present an 'environmentally friendly' image (savings of primary energy inputs, reductions in solid waste disposal requirements). Commercial decisions to invest in waste incineration options therefore must take account of a variety of supply cost, regulatory, and social factors that render uncertain the economic viability and social legitimacy of the choice.     

Chemical Manufacturers Association 1984 Hazardous Waste Survey

This paper discusses the Chemical Manufacturers Association's 1984 survey of the chemical industry's hazardous waste management practices. The survey data include a breakdown of how the industry's hazardous wastes are managed, detailing generation, treatment and disposal, and cover 725 plants in 81 companies. The 1984 survey is the third CM A hazardous waste survey, and the paper discusses resultant waste treatment trends from 1981- 1984, the period covered by previous surveys. A total of 278.5 million tons of hazardous waste was treated and disposed by survey respondents. Of this, 276.8 million tons was hazardous wastewater and 1.7 million tons was solid hazardous waste. The survey solid hazardous waste total was projected to the entire industry (Standard Industrial Code 2800) and is estimated at 6.9 million tons. The survey showed continued decreasing trends in hazardous waste generation in the chemical industry. It demonstrated changes in hazardous waste management practices, with decreased use of landfills and increased incineration of the solid wastes that are generated.     

Medical Waste Disposal

Medical (biomedical) wastes pose numerous potential health and safety hazards. In addition to their infectious and toxic characteristics, the highly variable and inconsistent nature of medical waste streams has increased public concern about storage, treatment, transportation, and ultimate disposal.

In recent years, techniques have been developed to reduce human exposure to the toxic and infectious components of medical wastes. The most commonly used techniques include internal segregation, containment, and incineration. Other common techniques include grinding, shredding, and disinfection, e.g., autoclaving and chemical treatment followed by landfilling.

Of all the available technologies for medical waste treatment and disposal, incineration has been found to be the most effective method overall for destroying infectious and toxic material, volume reduction, and weight reduction in the medical waste stream, incineration destroys the broadest variety of medical waste constituents and can recover energy from the medical waste stream. Incineration also is an appropriate alternative to burial of human pathological remains.     

Incineration of hazardous wastes from the petroleum industry in Nigeria

Persistent hazardous wastes are produced in the recovery, processing and upgrading of crude petroleum in Nigeria. However, recent developments in environmental pollution control are drawing increasing attention to the problems of hazardous wastes. The ever-increasing need to control these wastes from the petroleum industry often compels the chemical engineer to specify methods of treatment and disposal. Present methods for disposal are becoming increasingly undesirable for a number of reasons, and incineration is being considered as an alternative. This paper reviews the extent of hazardous waste generation from the Nigerian petroleum industry and its environmental implications. It also examines the current disposal methods and the incineration technology option. The major chemical engineering concepts of the incineration process and the principles guiding their operations are discussed. The potential for the use of incineration is examined, as well as information that would aid the choice of incineration system for new applications.     

Afriwaste The fixation and stabilisation of hazardous waste

The disposal of hazardous and toxic wastes is an area where utmost care and responsibility needs to be exercised. A certain (and mostly acceptable) level of care and responsibility has been legislated and is in place in most developed economies (UK, USA, Canada, Europe, etc.). This is, however, generally not the case in under-developed or developing economies, South Africa being no exception. This paper reflects on various disposal methods and describes a potentially economic alternative to existing methods of the disposal of toxic and hazardous wastes. These existing methods are: Disposal in Class I landfill sites and destruction via incineration.     

A Discussion of Regulatory Requirements and Air Dispersion Modeling Approaches Applicable to U.S. Chemical Demilitarization Facilities

ABSTRACT

Owners of hazardous waste treatment, storage, and disposal facilities, and certain major air pollution sources, must conduct several separate ambient air dispersion modeling analyses before beginning construction of new facilities or modifying existing facilities. These analyses are critical components of the environmental permitting and facility certification processes and must be completed to the satisfaction of federal, state, and local regulatory authorities.

The U.S. Army has conducted air dispersion modeling for its proposed chemical agent disposal facilities to fulfill the following environmental regulatory and risk management requirements: (1) Resource Conservation and Recovery Act human health and ecological risk assessment analysis for the hazardous waste treatment and storage permit applications, (2) Quantitative Risk Assessment to support the site-specific risk management programs, and (3) Prevention of Significant Deterioration ambient air impact analysis for the air permit applications. The purpose of these air dispersion modeling studies is to show that the potential impacts on human health and the environment, due to operation of the chemical agent disposal facilities, are acceptable. This paper describes and compares the types of air dispersion models, modeling input data requirements, modeling algorithms, and approaches used to satisfy the three environmental regulatory and risk management requirements listed above. Although this paper discusses only one industry (i.e., chemical demilitarization), the information it contains could help those in other industries who need to communicate to the public the purpose and objectives of each modeling analysis. It may also be useful in integrating the results of each analysis into an overarching summary of compliance and potential risks.     

Emissions behavior and distribution of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) from cement kilns in China

The production of cement in China is accompanied by various emissions, such as fine particulate matter, heavy metals, nitrogen oxides, sulfur oxides, carbon dioxide…. Moreover, cement kiln presents a potential health risk to its surroundings, linking to emissions of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), in brief dioxins. Flue gas samples were collected from five typical cement kilns during twelve runs and were used to evaluate the levels and distribution of PCDD/Fs in the emissions from cement kilns. The PCDD/Fs concentrations (136 congeners) and I-TEQ values ranged from 2.3 to >40 ng/m³ and 9.3?～?90.8?×?10^?3 ng I-TEQ/m³, respectively, which were lower than the emission standard in China (0.1 ng I-TEQ/m³). In weight units, the dominant congeners were OCDD, 1,2,3,4,6,7,8-HpCDF, and OCDF; 2,3,4,7,8-PeCDF is the largest contributor (36–66 %) to the total I-TEQ value of twelve runs. HxCDF and TCDF were the first two most abundant homologue groups (12–85 and 4–52 %), and the homologue concentration decreased with rising chlorine number for PCDDs. In addition, there was no marked difference in homologue profiles when solid wastes (refuse-derived fuel and municipal solid waste) and hazardous wastes (DDT and POPs) were combusted as supplemental fuels. The use of various supplemental fuels had no obvious effect on the fingerprint of PCDD/F homologues. Moreover, there was no significant difference in levels of PCDD/Fs emission due to the diversity of production capacity, which were consistent with reported previously. Air pollution control device had effect on the homologue profiles, and cement system with electrostatic precipitators (ESP) had more fractions of octachloro congeners to the total.     

Avoiding Land Disposal of Hazardous Waste

In response to a growing societal mandate, land disposal of hazardous wastes is gradually being replaced by treatment technologies. This shift to "alternative technologies" is the result of the impacts of past land disposal practices on other environmental media (groundwater, surface water, and air). A prime motivation for adopting alternatives to land disposal is to eliminate these cross-media impacts. Alternative technologies, however, can themselves have cross-media environmental impacts which must be recognized and addressed before such technologies are extensively applied. This paper discusses hazardous waste constituents, common disposal practices, alternative technologies currently being applied, possible cross-media environmental impacts of the alternative technologies, and proposed methods of mitigating these environmental impacts. Case studies from uncontrolled hazardous waste sites and industrial operations are used to illustrate the application of alternative technologies. Case studies include the application of waste treatment technologies as well as the adoption of waste minimization techniques.     

宁波市危险废物管理、处置现状和对策

对宁波市危险废物现状进行了调查,分析了危险废物的来源、产量、特征及存在的主要问题.在此基础上,提出了宁波市危险废物管理处置对策,具体包括:加强危险废物申报登记工作;健全宁波市危险废物管理法律体系和监督管理机构;建立合理的危险废物收费制度;源头控制危险废物污染和建设危险废物集中处置场等.     

Public Policy impacts on the Generation and Disposal of Hazardous Waste in New York State

A number of policies adopted by the federal government and the states have been designed to promote waste reduction or influence the choice of waste disposal technologies employed by generators of hazardous waste. Graphic analysis of smoothed time series data for hazardous wastes manifested in New York State for the period between June 1982 and February 1987 suggests that some of these policies have had the intended effects.

Significant shifts in manifested waste volumes are evident that coincide with the following policy interventions: (1) increased state waste-end tax rates; (2) state and federal landfill bans; (3) federal restrictions on burning hazardous wastes and waste oils for energy recovery; and (4) changes in the federal regulatory definition of hazardous waste. Other changes in waste generation and management appear to be attributable to such factors as state and regional economic conditions and changes in instate treatment and disposal facility capacity. Analysis of the management of specific waste types supports evidence from the graphic analysis that waste generators changed from land disposal to “higher” waste handling technologies in response to several policy interventions.