UV peroxidation with air stripping for optimized removal of VOCs from groundwater

No one remedial technology is best suited to treat every groundwater contaminant plume. This article describes how pilot testing and analytical evaluation targeted selection of two treatment technologies, UV peroxidation and air stripping, to be used in series to create a synergistic, cost-effective pump-and-treat system for the removal of VOCs from groundwater. Pilot plant size equipment was employed to treat the VOC-contaminated groundwater in order to obtain site-specific reaction rates and to develop full-scale design parameters. It was found that by using the two treatment technologies in combination, the influent concentration of 2,000 ppb total VOCs could be reduced to less than 1 ppb, thus meeting drinking water standards.     

Characteristics of ashes from different locations at the MSW incinerator equipped with various air pollution control devices

The characteristics of ashes from different locations at a municipal solid waste incinerator (MSWI) equipped with a water spray tower (WST) as a cooling system, and a spray dryer adsorber (SDA), a bag filter (BF) and a selective catalytic reactor (SCR) as air pollution control devices (APCD) was investigated to provide the basic data for further treatment of ashes. A commercial MSWI with a capacity of 100 tons per day was selected. Ash was sampled from different locations during the normal operation of the MSWI and was analyzed to obtain chemical composition, basicity, metal contents and leaching behavior of heavy metals. Basicity and pH of ash showed a broad range between 0.08-9.07 and 3.5-12.3, respectively. Some major inorganics in ash were identified and could affect the basicity. This could be one of the factors to determine further treatment means. Partitioning of hazardous heavy metals such as Pb, Cu, Cr, Hg and Cd was investigated. Large portions of Hg and Cd were emitted from the furnace while over 90% of Pb, Cu and Cr remained in bottom ash. However 54% of Hg was captured by WST and 41% by SDA/BF and 3.6% was emitted through the stack, while 81.5% of Cd was captured by SDA/BF. From the analysis data of various metal contents in ash and leach analysis, such capturing of metal was confirmed and some heavy metals found to be easily released from ash. Based on the overall characteristics of ash in different locations at the MSWI during the investigation, some considerations and suggestions for determining the appropriate treatment methods of ash were made as conclusions.     

Effluents from MBT plants: Plasma techniques for the treatment of VOCs

Mechanical–biological treatments (MBTs) of urban waste are growing in popularity in many European countries. Recent studies pointed out that their contribution in terms of volatile organic compounds (VOCs) and other air pollutants is not negligible. Compared to classical removal technologies, non-thermal plasmas (NTP) showed better performances and low energy consumption when applied to treat lowly concentrated streams. Therefore, to study the feasibility of the application of NTP to MBTs, a Dielectric Barrier Discharge reactor was applied to treat a mixture of air and methyl ethyl ketone (MEK), to simulate emissions from MBTs. The removal efficiency of MEK was linearly dependent upon time, power and specific input energy. Only 2–4% of MEK was converted to carbon dioxide (CO₂), the remaining carbon being involved in the formation of byproducts (methyl nitrate and 2,3-butanedione, especially). For future development of pilot-scale reactors, acting on residence time, power, convective flow and catalysts will help finding a compromise between energy consumption, desired abatement and selectivity to CO₂.     

Development and evaluation of a mass spectrometer-based continuous emission monitor for volatile organic compound emissions from combustion devices

A mass spectrometer-based continuous emission monitor (MS-CEM) for organic compound emissions from combustion devices was developed and evaluated at the Louisiana State University (LSU) pilot-scale rotary kiln incinerator (RKI). The MS-CEM consists of a stack probe, heat-traced sampling line, vacuum pump, particulate filter, Nafion@ dryer and mass spectrometer. The mass spectrometer includes a computer that controls and optimizes the operation of the unit. The MS-CEM is capable of continuously analyzing up to 40 different volatile organic compounds on a real-time basis. The MS-CEM is capable of analyzing, computing and recording the analytical results for each and up to 40 different organic compounds in less than 0.3 s. Four different volatile organic compounds were mixed together and injected into the baghouse inlet while simultaneously analyzing each organic component exiting the RKI stack gas. The results obtained from MS-CEM were compared with the material balance values. The system response time (including the MS-CEM) varies from 1.1 to 1.5 min.     

An ecotoxicological evaluation of aged bottom ash for use in constructions

Municipal and Industrial Solid Waste Incineration (MISWI) bottom ash is mainly deposited in landfills, but natural resources and energy could be saved if these ash materials would be used in geotechnical constructions. To enable such usage, knowledge is needed on their potential environmental impact. The aim of this study was to evaluate the ecotoxicity of leachates from MISWI bottom ash, aged for five years, in an environmental relevant way using a sequential batch leaching method at the Liquid/Solid-ratio interval 1–3, and to test the leachates in a (sub)chronic ecotoxicity test. Also, the leachates were characterized chemically and with the technique of diffusive gradients in thin films (DGTs). By comparing established ecotoxicity data for each element with chemically analysed and labile concentrations in the leachates, potentially problematic elements were identified by calculating Hazard Quotients (HQ). Overall, our results show that the ecotoxicity was in general low and decreased with increased leaching. A strong correspondence between calculated HQs and observed toxicity over the full L/S range was observed for K. However, K will likely not be problematic from a long-term environmental perspective when using the ash, since it is a naturally occurring essential macro element which is not classified as ecotoxic in the chemical legislation. Although Cu was measured in total concentrations close to where a toxic response is expected, even at L/S 3, the DGT-analysis showed that less than 50% was present in a labile fraction, indicating that Cu is complexed by organic ligands which reduce its bioavailability.     

An overview of the US EPA’s multiple pathway exposure methodology

The US Environmental Protection Agency’s National Center for Environmental Assessment is finalizing its updated approach to assessing the health risks from direct and indirect exposure to combustion emissions. The prior 1990 Indirect Exposure Methodology has been used frequently in the early part of this decade, while the new methodology considers more pathways for agent transfer and exposure. This advanced methodology is not limited to exposure from combustion emissions as the approach lends itself to assessing indirect exposure to other agents in various exposure scenarios. The purpose of this presentation is to alert the user community to the new methodology and discuss its impacts on risk assessment. A brief overview of the exposure pathways, along with the inherent uncertainties of the MPE and the risk characterization, are presented. Other associated documentation is presented and referenced. The paper concludes with a discussion of the planned implementation of the MPE and the Agency program guidance for use with RCRA combustor permitting and risk assessments.     

Chlorinated vapor intrusion indicators,tracers, and surrogates (ITS): Supplemental measurements for minimizing the number of chemical indoor air samples—Part 1: Vapor intrusion driving forces and related environmental factors

Vapor intrusion (VI) assessment is complicated by spatial and temporal variability, largely due to compounded interactions among the many individual factors that influence the vapor migration pathway from subsurface sources to indoor air. Past research on highly variable indoor air datasets demonstrates that conventional sampling schemes can result in false negative determinations of potential risk corresponding to reasonable maximum exposures (RME). While high‐frequency chemical analysis of individual chlorinated volatile organic compounds (CVOCs) in indoor air is conceptually appealing, it remains largely impractical when numerous buildings are involved and particularly for long‐term monitoring. As more is learned about the challenges with indoor air sampling for VI assessment, it has become clear that alternative approaches are needed to help guide discrete sampling efforts and reduce sampling requirements while maintaining acceptable confidence in exposure characterization. Indicators, tracers, and surrogates (ITS), which include a collection of quantifiable metrics and tools, have been suggested as a potential solution for making VI pathway assessment and long‐term monitoring more informative, efficient, and cost‐effective. This review, compilation, and evaluation of ITS demonstrates how even low numbers of indoor air CVOC samples can provide high levels of confidence for representing the RME levels (e.g., 95th percentile) often sought by regulatory agencies for less than chronic effects. A two‐part compilation of available evidence for select low‐cost ITS is presented, with Part 1 focused on introducing the concepts of ITS, meteorologically based ITS, and the evidence from data‐rich studies to support lower cost CVOC VI assessments. Part 1 includes the results of quantitative analyses on two robust residential building VI datasets, where numerous supplemental metrics were collected concurrently with indoor air concentration data. These are supplemented with additional less‐intensive studies in different circumstances. These analyses show that certain ITS metrics and tools, including differential temperature, differential pressure, and radon (in Part 2), can provide benefits to VI assessment and long‐term monitoring. This includes indicators that narrow the assessment period needed to capture RME conditions, tracers that enhance understanding of the conceptual site model, and aid in the identification of preferential pathways and surrogates that support or substitute for CVOC sampling results. The results of this review provide insight into the scientifically supportable uses of ITS.     

An evaluation on the environmental consequences of residual CFCs from obsolete household refrigerators in China

Chlorofluorocarbons (CFCs) contained in household refrigerators consist mainly of CFC-11 and CFC-12, which will be eventually released into the environment. Consequentially, environmental releases of these refrigerants will lead to ozone depletion and contribute significantly to the greenhouse effect, if waste refrigerators are not disposed of properly. In the present paper, the potential release of residual CFCs and their substitutes from obsolete household refrigerators in China is examined, and their contributions to ozone depletion and greenhouse effect are compared with those of other recognized ozone-depleting substances (ODS) and greenhouse gases (GHGs). The results imply that annual potential amounts of released residual CFC-11 and CFC-12 will reach their maximums at 4600 and 2300 tons, respectively in 2011, and then decrease gradually to zero until 2020. Meanwhile, the amounts of their most widely used substitutes HCFC-141b and HFC-134a will keep increasing. Subsequently, the contribution ratio of these CFCs and their substitutes to ozone depletion will remain at 25% through 2011, and reach its peak value of 34% by 2018. The contribution to greenhouse effect will reach its peak value of 0.57% by 2010. Moreover, the contribution ratio of these CFCs to the total global release of CFCs will steadily increase, reaching its peak of 15% by 2018. Thus, this period from 2010 to 2018 is a crucial time during which residual CFCs and their substitutes from obsolete household refrigerators in China will contribute significantly to ozone depletion.     

An evaluation of legislative measures on electrical and electronic waste in the People's Republic of China

With the increasing number of recycling mishaps in connection with waste electronic and electrical equipment (WEEE) in the People's Republic of China, it is imperative that the handling and recycling of WEEE be sufficiently regulated in China. Regulations covering three major issues, namely, take-back issues, controls on hazardous substances in WEEE and the assurance of good environmental management in WEEE plants, were promulgated between 2006 and 2008. The evaluation in this country report shows that few of these regulatory measures have performed satisfactorily in terms of enforcement, of public acceptance and of environmental concerns. In brief, the take-back requirements and the associated financial responsibilities are only vaguely defined; the control on hazardous substances and the so-called "environmental expiry date" requirements cannot be properly enforced, and the resources needed to ensure the satisfactory enforcement of the environmental abatement and pollution control requirements in WEEE plants are overwhelming. In addition, the use of a "multiple enforcement body" approach to the control of hazardous substances in WEEE is an indication that the Chinese government lacks the determination to properly enforce the relevant legal requirements.     

An evaluation of substrate degradation patterns in the composting process. Part 2: temperature-corrected profiles

In this paper, the patterns of 44 substrate degradation profiles obtained from the composting literature are examined following their correction to a constant temperature of 40 degrees C, using a new procedure presented in this work. The applicability of a single exponential model, a double exponential model and a non-logarithmic Gompertz model in describing their behaviour is then evaluated. Multi-phase profiles were most commonly seen, with convex shapes observed in only a relatively small proportion of the profiles. Convex shapes were also embedded within other profiles, either preceeded by a lag phase, or followed by non-convex behaviour. Sigmoidal patterns were relatively rare. Of the temperature-corrected data sets examined, 33 were found to be either not well modelled by, or inappropriate for, any of the above models. Two fits rated as good were obtained when using the single exponential model, and one fit rated as excellent, plus one fit rated as good, were obtained when using the double exponential model. A single fit rated as excellent was found when using the non-logarithmic Gompertz model. The lag phase, which was observed in many data sets, was successfully modelled using the non-logarithmic Gompertz function where excellent and good fits were obtained, but as expected this phase of the profile could not be modelled by either the single or double exponential functions. When the lag phase or post-convex curve data was removed from 20 data sets, use of the single exponential function resulted in three fits rated as excellent and two rated as good. When a double exponential model was applied to these data sets, three fits rated as good were obtained, whilst application of the modified Gompertz model gave one fit rated as good. The remainder of the fits were rated as moderate to fair. It is concluded that the evidence supporting the use of the single exponential model, the double exponential model or the non-logarithmic Gompertz model to describe full substrate degradation profiles in composting following their adjustment for temperature effects is limited. Further work is suggested in order to investigate the nature of those profiles which were not well modelled, to more precisely ascertain the cardinal temperatures for composting used in the function of Rosso et al. (1993) [Rosso, L., Lobry, J.R., Flandrois, J.P., 1993. An unexpected correlation between cardinal temperatures of microbial growth highlighted by a new model. J. Theor. Biol 162, 447-463.], which was employed in the present temperature correction procedure, and to incorporate correction for varying moisture and oxygen concentrations.     

Evaluation of the available air pollution control technologies for achievement of the MACT requirements in the newly implemented new source performance standards (NSPS) and emission guidelines (EG) for hospital and medical/infectious waste incinerators

After many years of research and debate, in August of 1997 the United States Environmental Protection Agency (EPA) issued New Source Performance Standards (NSPS) and Emission Guidelines (EG) for medical/infectious waste incinerators in the United States. These new emissions and operational standards establish considerably more restrictive limitations on air emissions for medical/infectious waste incinerators and will undoubtedly have a significant impact on the over 2300 hospitals presently operating an incinerator on-site. This paper will explore the options available to these facilities, and those facilities which may be considering installation of an incinerator, relative to achieving compliance with the NSPS and EG for medical/infectious waste incinerators.     

Toxicological evaluation of the chemical oxidation methods for landfill stabilization

As the stabilization criteria for landfill sites, only chemical criteria for the leachate discharges from the landfill sites have been used in Japan and many other countries. Recently, chemical oxidation has been developed as a method for the early-stabilization of landfills. However, by-products that are difficult to detect by chemical analysis can be produced by this method. Therefore, toxicity tests are useful tools for detecting the changes of leachate quality after application of this method. The heat source in the A landfill was analyzed by organic position inquiry technology, and ozone-treated leachate was sprayed back to the heat source in the landfill. Toxicity changes of the leachate after the spray were monitored using Microtoxtrade mark, ToxScreen-II, and DaphTox tests. The hardly-degradable organic matter was efficiently removed and toxicities of the leachate in the heat source decreased after the application. These toxicity results were significantly related to chemical oxygen demand (COD) changes. Thus, it was concluded that the toxicity tests were effective for monitoring the leachate quality after applying the chemical oxidation method for landfill stabilization, and its incorporation to establish the criteria for early-stabilization of landfill sites needs to be considered.     

Techniques for the evaluation of maturity for composts of industrially contaminated lake sediments

Composting was applied as a bioremediation methodology for the reclamation of dredged sediments of Isnapur, Khazipally and Gandigudem lakes polluted with industrial wastes. The present study is an attempt to elaborate upon organic matter transformations and define the parameters for product maturity adapting chemical and spectroscopic methods during composting. The stability and maturity of sediments were evaluated by assessing parameters like C/N ratio, nitrification index (NH(4)-N/NO(3)-N), water-soluble organic carbon concentration, CO(2) evolution rate, cation exchange capacity and indices such as humification index, E4/E6 ratio, compost mineralization index (ash content/oxidizable carbon), germination index, dehydrogenase, polyphenoloxidase activities and FTIR spectroscopy. The results showed that the changes in the above chemical and biological parameters can be employed as reliable indicators of stability and maturity. The FTIR spectra revealed enrichment in the aromatic groups and a degradation of the aliphatic groups indicating stabilization of the final compost.     

Calculation of carbon balances for evaluation of the biodegradability of polymers

Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO₂ release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

A model for evaluating the social performance of construction waste management

It has been determined by existing literature that a lot of research efforts have been made to the economic performance of construction waste management (CWM), but less attention is paid to investigation of the social performance of CWM. This study therefore attempts to develop a model for quantitatively evaluating the social performance of CWM by using a system dynamics (SD) approach. Firstly, major variables affecting the social performance of CWM are identified and a holistic system for assessing the social performance of CWM is formulated in line with feedback relationships underlying these variables. The developed system is then converted into a SD model through the software iThink. An empirical case study is finally conducted to demonstrate application of the model. Results of model validation indicate that the model is robust and reasonable to reflect the situation of the real system under study. Findings of the case study offer helpful insights into effectively promoting the social performance of CWM of the project investigated. Furthermore, the model exhibits great potential to function as an experimental platform for dynamically evaluating effects of management measures on improving the social performance of CWM of construction projects.     

燃煤电厂灰场环评技术评估中存在的问题与建议

在比较我国一般工业固体废物贮存处置场、生活垃圾填埋、危险废物贮存和危险废物填埋污染控制标准的基础上,结合欧共体和德国对固体废物的分类和填埋要求、德国灰场的防渗实例和我国燃煤电厂实际运行灰场对地下水的环境影响,分析了《一般工业固体废物贮存、处置场污染控制标准》(GB 18599-2001)存在的问题,并建议在干灰场环评技术评估中,燃煤电厂的灰渣和脱硫石膏除非按GB 5086规定方法进行浸出试验获得的浸出液中第一类污染物超过GB 8978最高允许排放浓度外,均应按第I类一般工业固体废物处理;同时对燃煤电厂的干灰场场址选择等方面的环保要求提出了建议.     

Development of a MSW classification system for the evaluation of mechanical properties

To date, sparse information is available on the mechanical properties of municipal solid waste and the results of published work are often hard to compare due to differences in waste composition and therefore properties. To allow comparison, a unified classification system for waste is deemed crucial. Existing classification systems are presented and discussed. For a geotechnical classification, mechanical properties, size, shape and degradability potential of waste components have to be taken into account. A new and improved classification system for waste components is proposed, which complies with the requirements of a geotechnical classification system. It classifies waste components based on: (1) their material engineering properties (e.g., shear, compressive and tensile strength), (2) a size distribution of the components, (3) the component shape (reinforcing, compressible and incompressible), and (4) the degree of degradability. The proposed classification system is applied to data from the literature and methods for presenting classification information are demonstrated. Further work required to develop a full classification system for waste bodies is highlighted.     

Application of the rescue number to the evaluation of remediation technologies for contaminated ground

An improved rescue number, RN_SOIL, which is an indicator for evaluating remediation technologies for contaminated ground that is based on both the risk and the remediation cost, is proposed as a tool of risk communication. The risk posed by contaminated ground is indicated by the figure of treatment priority at time t, FTP(t), which represents the human health risk as the number of people affected by the contaminated ground at time t during the remediation process. The calculation of the value of FTP(t) is based on exposure to contaminants that have migrated through environmental media from the contaminated ground, and is estimated by using a CalTOX model and the Monte Carlo method. The integration of FTP(t) with time, which represents the cumulative number of people affected by the contaminated ground, is used to estimate the performance of individual remediation technologies in risk reduction. The figure of unprocessibility for waste (FUW), which represents difficulties in remediation, is expressed as the remediation cost. FUW is estimated by using actual costs per unit volume of remediated soil. As an overall performance value, the rescue number for each remediation technology for contaminated ground (RN_SOIL) is calculated by multiplication of the integral FTP(t) by FUW. Smaller values of RN_SOIL are judged to indicate a better technology. The rescue index (RI), calculated as the ratio of the reduction of the integral FTP(t) to FUW, indicates the cost-effectiveness of the remediation technologies. Successful estimation of the indices (FTP(t), integral FTP(t), FUW, RN_SOIL and RI) demonstrate the usefulness of these indices in risk communication.Part of this paper was presented at 13th meeting of Japan Society of Waste Management Experts (2002)     

The evaluation of an analytical protocol for the determination of substances in waste for hazard classification

The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC–MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of ‘pools’ of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved ‘mass’ during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved ‘pools’) should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited.