Efficient waste-to-energy system as a contribution to clean technologies

This paper deals with the problem of efficient energy utilization in the field of thermal processing of waste (waste-to-energy). An up-to-date incineration plant cannot be considered as only waste disposal facility. The waste combustion (incineration) processes are accompanied by release of large amount of energy, that shall be effectively utilized (e.g. steam production and its export to consumers, power generation, cogeneration). In addition to the main purpose of incineration, i.e. treating the specified amount of waste, waste-to-energy systems are able to some extent substitute conventional energy production plants fired by fossil fuel and thus to contribute to solving global environmental problems. For example, methodology presented in Reference Document on the Best Available Techniques for Waste Incineration (BREF) can be used for assessment of plant performance from the view of energy utilization. This approach is based on evaluation of criterion Plant Efficiency. An existing incineration plant has been evaluated and results are presented and discussed. In the future, it has been expected that evaluation like this will be obligatory for every plant. The arrival of more and more sweeping environmental limits represents a driving force for retrofit. At the same time maximum heat recovery and efficient energy utilization should be required. Influence of different operational modes (type of waste incinerated, combustion temperature, air-preheating etc.) and lay-out of heat recovery system (e.g. cogeneration) on plant performance has been investigated. A mathematical model based on combination of basic auxiliary operations and simple thermodynamic models of heat engines has been created with the aid of a specific computational tool. Its conception is based on both requirements and experience coming from industry. The most serious problem of effectively running incineration plants consists in economical utilization of energy produced. Examples of integration into existing energy systems are shown and discussed. An erratum to this article can be found at     

Automotive shredder residue (ASR): reviewing its production from end-of-life vehicles (ELVs) and its recycling, energy or chemicals' valorisation

ASR is in Europe classified as hazardous waste. Both the stringent landfill legislation and the objectives/legislation related to ELV treatment of various countries, will limit current landfilling practice and impose an increased efficiency of the recovery and recycling of ELVs. The present paper situates ASR within the ELV context. Primary recovery techniques recycle up to 75% of the ELV components; the remaining 25% is called ASR. Characteristics of ASR and possible upgrading by secondary recovery techniques are reviewed. The latter techniques can produce a fuel- or fillergrade ASR, however with limitations as discussed. A further reduction of ASR to be disposed of calls upon (co-)incineration or the use of thermo-chemical processes, such as pyrolysis or gasification. The application in waste-to-energy plants, in cement kilns or in metallurgical processes is possible, with attention to the possible environmental impact: research into these impacts is discussed in detail. Pyrolysis and gasification are emerging technologies: although the sole use of ASR is debatable, its mixing with other waste streams is gradually being applied in commercial processes. The environmental impacts of the processes are acceptable, but more supporting data are needed and the advantage over (co-)incineration remains to be proven.     

Treatment of hazardous sorbents generated from the adsorption of heavy metals during incineration

The emission of heavy metals during waste incineration can be effectively reduced through the practice of employing non-toxic sorbents. These sorbents can react with toxic metals at high temperatures and create metal binding between them by various physical and chemical mechanisms. After the adsorption process, the used sorbents, which contain heavy metals, need to be desorbed to reduce their potential environmental hazards or provide reusable sorbents for economical aspect. The sorbent's adsorption efficiency is affected by different operating conditions and waste elemental compositions during incineration, which, in turn, affect their desorption characteristics. However, the effects of operating condition and waste elemental composition on the stability of heavy metals in the sorbents and the desorption efficiencies have been little studied. This study investigates the desorption characteristics of heavy metals (Cr, Pb, Cu, and Cd) from the hazardous sorbents with different extracting reagents (H(2)O, HCl, EDTA, and Na(2)S(2)O(5)). The hazardous sorbents were generated under different adsorption time and various input waste elemental compositions during incineration process.     

Incineration and gasification technologies completed with up-to-date off-gas cleaning system for meeting environmental limits

It is shown how gasification can be used for processing wastes including “waste to energy” system. First, an analysis of incineration of wastes taking into account environmental limits is performed. This analysis is aimed at a typical arrangement of a conventional oxidizing incineration plant consisting of waste storage and feeding systems, two-stage incinerator (primary and secondary combustion chambers), heat recovery system involving co-generation and off-gas cleaning system. It is also focused on a new arrangement where the primary combustion chamber (rotary kiln) is substituted by gasification reactor. The proposed concept with a fluidised bed reactor utilizes results of experimental research with various mixtures of wastes (e.g. shredded textile and rubber) considering typical conditions of operation. Experiments provide us with various important characteristics (heat value of produced syngas vs. temperature in the gasification reactor, temperature in the secondary combustion chamber vs. oxygen concentration in outlet flue gas and heat value of syngas, etc.). Then it is possible to make a comparison of conventional incineration and gasification for a concrete industrial process involving a unit for thermal treatment of hazardous industrial waste mixed with municipal solid wastes with capacity of 10,000 t/year. The application of gasification technology brings about the whole range of benefits like minimizing the consumption of auxiliary fuel and decreasing size of the secondary combustion chamber and other subsystems of the incineration plants. Involving such a system with energy and investment cost reduction into an industrial process contributes to meeting cleaner production and environmental legislation regulations.     

Carbon fibre reinforced composite waste: An environmental assessment of recycling,energy recovery and landfilling

The environmental benefits of recycling are assessed against other end-of-life (EOL) treatments for Carbon Fibre Reinforced Plastic (CFRP) waste. Recycling via pyrolysis, incineration with energy recovery, and disposal via landfilling are compared. To account for physical changes to materials from use and recycling, equivalence between recycled and virgin materials is calculated based on the ability to produce a short fibre composite beam of equivalent stiffness. Secondary effects of using Recycled Carbon Fibre (RCF) in a hypothetical automotive application are also analysed. Results underline the ecological constraints towards recycling CFRPs and demonstrate that benefits from recycling are strongly linked to the impacts of the selected recovery process, the materials replaced by RCF in a secondary application, and also to the type of secondary application in which they are used.     

Applying industrial ecosystem indicators: case of Pielinen Karelia,Finland

This paper presents an industrial ecological insight into local waste management in Pielinen Karelia, Finland. There local system is experiencing major changes because of tightening EC waste legislation including the directives on waste incineration (2000/76/EC) and landfilling of wastes (1999/31/EC). Small local landfills are closing and most of municipal wastes will be transported 120–180 km to large-scale waste management centre in Kuopio. The paper applies three industrial ecosystem indicators, based on environmental, economic and employment impacts of different waste management technologies. Environmental indicator is CO₂ equivalent emission, economic indicator is based on costs and revenues of waste management, and social (i.e. employment) indicator includes new jobs generated. The results indicate that waste incineration option in forthcoming regional cooperation could create emission savings up to 117–394 kg CO₂ eqv./ton of municipal waste when compared to local landfilling. As economic impacts, new regional cooperation and long-distance transportations will increase the costs from previous 45.6–55.2 €/ton in local landfilling to 97.4 €/ton in regional landfilling and 120.8–126.9 €/ton in regional REF-III incineration. In terms of employment, the new cooperation could create 2–6.5 new jobs. The regional cooperation results to rising operational costs but avoids investments to new local infrastructure. It also creates significant emission savings, maintains current employment in waste handling and creates new jobs in long-distance transportation.

A study on the chemical and mineralogical characterization of MSWI fly ash using a sequential extraction procedure

The presence of heavy metals in municipal solid waste incineration (MSWI) fly ash is of environmental concern due to their leaching potential in landfill environments. Sequential chemical extraction was performed on fly ash samples from a large-scale municipal solid waste incineration plant in East China. The transformation of the mineralogical species of fly ash during the sequential extraction was studied using X-ray fluorescence (XRF) and X-ray powder diffraction (XRD). The leaching behavior of heavy metals such as zinc, lead, cadmium and copper in MSWI fly ash was considered to have a dependency relationship with the components of calcium, such as aphthitalite, calcite, anhydrite and calcium aluminate or calcium aluminosilicate.     

Incineration of municipal and assimilated wastes in France: assessment of latest energy and material recovery performances

Incineration has an important place in waste management in France. In 2003, around 130 incineration plants have treated 12.6 Mt of non-dangerous waste, mainly composed of household waste (10.8 Mt), non-dangerous waste from industry, business, services (1.0 Mt), sewage sludge (0.2 Mt) or clinical waste (0.1 Mt). The incineration of these wastes generated 3.0 Mt of bottom ash of which 2.3 Mt were used for roads construction and 0.2 Mt of ferrous and non-ferrous metal were recycled. It also produced 2,900,000 MWh of electricity, of which 2,200,000 MWh were sold to Electricité de France (EDF) and 9,100,000 MWh of heat, of which 7,200,000 MWh were sold to private or public users. These French incinerators of non-hazardous waste are currently being thoroughly modernized, thus making possible the consolidation and the enhancement of their environmental and energy performance. This process is related to the implementation of the European Directive 2000/76/CE whose expiration date is 28 December 2005. Upon request of ADEME, the engineering company GIRUS has realised the first technical and economical evaluation of works necessary to bring incinerators into compliance. The financial estimations, carried out in 30 June 2003, show that the investments to be devoted could reach 750 million euros. This assessment shed new light on the situation of non-hazardous waste incinerators, including an identification and a rank ordering for each incinerator of the most frequent and the most complex non-conformities to be solved in term of cost and delay. At last, this assessment gives the solutions for each non-compliance.     

Emissions investigation for a novel medical waste incinerator

Medical waste constitutes one of the waste streams that should be dealt with special priority due to its potential negative impact on public health and on the environment. Incineration is a process that is widely used for the treatment of medical waste. However, self-supporting combustion of medical waste cannot avoid releasing many hazardous pollutants into our environment. The most favored solutions are firing additional fuels of high calorific value and direct purification by air pollution control devices (APCD). This process entails not only large first time investment but also an increase in the operation cost. A novel incinerator is proposed for better utilization of energy of the incineration process. Its originality is essentially due to combining a feeder, a rotary grate, a cylindrical gasifier and a “coaxial” secondary combustion chamber into a unique unit. The structure of the incinerator as well as the principle of the incineration process is presented in this paper. A full-scale trial of the novel incinerator with APCD was carried out from March to May 2008 to investigate how the distinct configuration influenced the incineration process. Data on PM, CO, NO_X, O₂ were recorded by a continuous emission monitoring system during the study period. Heavy metals and PCCD/Fs were also sampled and measured. Measuring results were compared with the China and U.S. EPA guidelines. The concentrations of contaminants were below their respective limits in emission control standards. Results from testing the novel medical waste incinerator confirmed that this technology has a good suitability for neutralization of medical wastes and purification of flue gases.     

Environmental life-cycle comparisons of two polychlorinated biphenyl remediation technologies: incineration and base catalyzed decomposition

Remediation action is critical for the management of polychlorinated biphenyl (PCB) contaminated sites. Dozens of remediation technologies developed internationally could be divided in two general categories incineration and non-incineration. In this paper, life cycle assessment (LCA) was carried out to study the environmental impacts of these two kinds of remediation technologies in selected PCB contaminated sites, where Infrared High Temperature Incineration (IHTI) and Base Catalyzed Decomposition (BCD) were selected as representatives of incineration and non-incineration. A combined midpoint/damage approach was adopted by using SimaPro 7.2 and IMPACTA2002+ to assess the human toxicity, ecotoxicity, climate change impact, and resource consumption from the five subsystems of IHTI and BCD technologies, respectively. It was found that the major environmental impacts through the whole lifecycle arose from energy consumption in both IHTI and BCD processes. For IHTI, primary and secondary combustion subsystem contributes more than 50% of midpoint impacts concerning with carcinogens, respiratory inorganics, respiratory organics, terrestrial ecotoxity, terrestrial acidification/eutrophication and global warming. In BCD process, the rotary kiln reactor subsystem presents the highest contribution to almost all the midpoint impacts including global warming, non-renewable energy, non-carcinogens, terrestrial ecotoxity and respiratory inorganics. In the view of midpoint impacts, the characterization values for global warming from IHTI and BCD were about 432.35 and 38.5 kg CO(2)-eq per ton PCB-containing soils, respectively. LCA results showed that the single score of BCD environmental impact was 1468.97 Pt while IHTI's score is 2785.15 Pt, which indicates BCD potentially has a lower environmental impact than IHTI technology in the PCB contaminated soil remediation process.     

Energy recovery from heavy ASR by co-incineration in a fluidized bed combustor

Automotive shredder residue (ASR) is a heterogeneous waste stream with varying particle size and elemental composition. Owing to its complexity and hazardous characteristics, landfilling of ASR is still a common practice. Nevertheless, incineration with energy recovery of certain ASR fractions (Waste-to-Energy, WtE) emerges as an interesting alternative. In a full scale experiment, a waste mix of 25 % heavy ASR, 25 % refuse derived fuel (RDF), and 50 % waste water treatment (WWT) sludge was incinerated in the SLECO fluidized bed combustor (FBC) at the Indaver site in Antwerp, Belgium. Input and output streams were sampled and analyzed to make an inventory of the most important pollutants and toxics. The inventory was further used to determine the environmental impact. Results are compared to those of two other scenarios: incineration of the usual waste feed (70 % RDF and 30 % WWT sludge) and co-incineration of 39 % ASR with 61 % WWT sludge. It can be concluded that co-incineration of heavy ASR in an existing FBC is a valid and clean technology to increase current reuse and recovery rates. In the considered FBC, 27 % of the energetic value of ASR can be recovered, while all emissions remain well below regulatory limits and only 12.6 % of the heavy ASR needs to be landfilled. The proportion of ASR in the input waste mix is however limited by the heavy metal concentration in the ASR and the generated ashes.     

国内外生活垃圾焚烧发电技术进展

随着人们对环境方面要求的日益增长,垃圾合理处理在践行绿色发展理念和推动生态文明建设进程中发挥着越来越重要的作用。生活垃圾焚烧发电技术作为固废资源利用的一种方法,如今已经演变成为一种成熟的资源利用技术。分别从垃圾焚烧发电行业的上、中、下游,即从垃圾焚烧的原料性质、燃烧发电技术以及烟气控制方面对国内外生活垃圾焚烧技术进行了比较分析,认为随着生活垃圾量日益增长,生活垃圾焚烧技术仍是一种实现减量化、资源化必不可少的手段,但是需要提升焚烧技术,改进国产焚烧工艺,严格控制焚烧烟气中污染物的排放,建立实时监测点,避免造成二次污染。     

废旧油墨的再生处理与利用的研究

目前废弃的油墨越来越多,对废弃物大多采取焚烧和掩埋的方式进行处理,对环境造成了极大的污染。采用对废旧油墨进行共沸蒸馏的方法,去除废弃油墨中大量的溶剂和水(润版液),经研磨、调色等加工处理,使废弃的油墨变为黑色油墨,进行再利用,并减少废弃物对环境的污染。     

Sequential extraction for evaluating the leaching behavior of selected elements in municipal solid waste incineration fly ash

A sequential extraction method has been applied for the determination of binding forms of trace elements in the municipal solid waste incineration (MSWI) fly ash and evaluating their leaching behavior in view of their potential environmental impact. The elemental determinations in the different leachates are performed by ICP-AES and ICP-MS, respectively. The morphology and mineralogical phases after extraction step were performed by scanning electron microscopy (SEM). Total of 20 elements in the samples are investigated. A reference material of city waste incineration fly ash (BCR No. 176) is also tested to examine the applicability as well as accuracy of the proposed method. The sum of most elements present in the individual fractions shows a good agreement with the total elemental concentrations. The extraction efficiencies are generally higher than 80% except for that of Cr and V. The extractable data of most elements give information about the binding forms of various elements in both incineration fly ashes. It was found that the elements such as Ca, K, Na, Pb, Zn, Cd, Cu and Sr have exhibited a remarkable mobility in fly ash. More than half of them would be dissolved or exchanged under a mild leaching condition. The toxic elements such as Pb, Cd, Zn and Cu have a great potential to be released into the environment under normal conditions.     

A comparision of regulated chemicals versus emitted PICs and PICs for risk analysis

In general, toxic combustion byproducts (TCBs) are the unwanted residues remaining in flue gases, combustion ashes, and wastewaters from the operation of an incineration or combustion facility. If a combustor is not well designed and operated, it may emit too high a level of TCBs. Categories of TCBs and some example constituents are as follows:

1. 1. Acid gas: HCl, NO_x and SO₂;

2. 2. Organics: Hydrocarbons such as dioxins and furans (PCDDs and PCDFs);

3. 3. Particulates: Trace metals (conventional metals and radioactive metals) and soots;

4. 4. Contaminants in ash; and

5. 5. Contaminants in spent wastewater.

Pollutants in Category (2) above are generally considered to be the products of incomplete combustion (PICs) in the field of hazardous waste incineration.

TCBs has been one of the major technical and sociological issues surrounding the use of incineration as a waste treatment alternative. Because of the complexity and controversy, the U.S. EPA issued a draft “Combustion Strategy” on May 18, 1993. The objective of the “Combustion Strategy” was to address the needs of and to outline the approaches for upgrading the existing incineration standards to better control TCB emissions.

This article lists those chemicals and metals which are regulated by two major U.S. environmental laws, namely, the Clean Air Act Amendments (CAAA) of 1990 and the Resource Conservation and Recovery Act (RCRA) of 1976. The CAAA is to regulate the air emissions from major sources, and the RCRA is to protect human health and the environment from the management of solid wastes, particularly from waste incineration. This paper also lists the PIC chemicals that were studied under U.S. EPA incineration research programs in the 1980s and the PIC chemicals that EPA permit writers are considering be the subject of risk analyses during the process of industry's applying for an incinerator operating permit.     

Application of methods (sequential extraction procedures and high-pressure digestion method) to fly ash particles to determine the element constituents: a case study for BCR 176

Sequential extraction procedures and the high-pressure digestion method were selected to determine the element constituents of fly ash samples. Sequential extraction is one of the most useful methods used to measure the various elements from municipal solid waste incineration ash and contaminated soils. The extract from each step is analyzed using various techniques and equipment, and the results are then evaluated. In this work, a six-step extraction procedure modified from that of Tessier et al. and Wang et al. was performed and applied to the certified reference material BCR 176 (city waste incineration ash). Analyses were carried out by various techniques such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), and X-ray powder diffraction (XRPD) to evaluate the characteristics of fly ash. The extraction efficiency of many elements was higher than 80%, and the relative standard deviations (RSD) for recovery of most elements were within 10%. In addition, an H(2)O(2)+HNO(3)+HF mixed acid digestion solution processed using a low-temperature evaporation procedure was selected as the optimal process for fly ash digestion. The results of this work provide information on the chemical composition, distribution, and potential mobility of the investigated elements.     

A life cycle assessment of destruction of ammunition

The Swedish Armed Forces have large stocks of ammunition that were produced at a time when decommissioning was not considered. This ammunition will eventually become obsolete and must be destroyed, preferably with minimal impact on the environment and in a safe way for personnel. The aim of this paper is to make a comparison of the environmental impacts in a life cycle perspective of three different methods of decommissioning/destruction of ammunition, and to identify the environmental advantages and disadvantages of each of these destruction methods: open detonation; static kiln incineration with air pollution control combined with metal recycling, and a combination of incineration with air pollution control, open burning, recovery of some energetic material and metal recycling. Data used are for the specific processes and from established LCA databases. Recycling the materials in the ammunition and minimising the spread of airborne pollutants during incineration were found to be the most important factors affecting the life cycle environmental performance of the compared destruction methods. Open detonation with or without metal recycling proved to be the overall worst alternative from a life cycle perspective. The results for the static kiln and combination treatment indicate that the kind of ammunition and location of the destruction plant might determine the choice of method, since the environmental impacts from these methods are of little difference in the case of this specific grenade. Different methods for destruction of ammunition have previously been discussed from a risk and safety perspective. This is however to our knowledge the first study looking specifically on environmentally aspect in a life cycle perspective.     

Energy recovery from waste incineration: economic aspects

If we consider the desirability of reducing fossil fuel consumption, together with the increasing production of combustible solid wastes, there is clearly a need for waste treatment systems which achieve both volume reduction and energy recovery. Direct incineration method is one such system. The aim of this work was to analyze the municipal solid waste incineration situated in the Province of Turin (Piedmont, North Italy), especially its economical effects in consequence of the energy recovery that can be achieved. In order to perform this analysis, two kinds of energy recovery have been studied: electric energy (electrical configuration) only, and both electric and thermal energy (cogenerative configuration). So after a reconstruction of the economic situation, by considering all the costs and revenues, for both the possible energetic configurations the correspondence between the environmental convenience (that was evaluated in a previously work) and the economic convenience has been defined. The main obtained results highlight that currently the environmental convenience corresponds to the cogenerative configuration; instead the economical convenience in the actual condition corresponds to the only electric configuration. Anyway, by working on the thermal energy price, it is possible to obtain at the same time an environmental and economic convenience.     

Utilization of municipal solid waste incineration ash in Portland cement clinker

Municipal solid waste incineration (MSWI) ash is used in part as raw materials for cement clinker production by taking advantage of the high contents of SiO₂, Al₂O₃, and CaO. It is necessary for environmental reasons to establish a material utilization system for the incineration waste ash residue instead of disposing these ashes into landfill. The aim of this paper is to study the feasibility of replacing clinker raw materials by waste ash residue for cement clinker production. MSWI bottom ash and MSWI fly ash are the main types of ashes being evaluated. The ashes were mixed into raw mixture with different portions of ash residue to produce cement clinker in a laboratory furnace at approximately 1400°C. X-ray diffraction and X-ray florescence techniques were used to analyze the phase chemistry and chemical composition of clinkers in order to compare these ash-based clinkers with commercial Portland cement clinker.     

罐装薯片包装的生命周期评价

对罐装薯片包装进行了生命周期评价,包括从原材料的获取、生产加工,工厂、消费者的运输,到包装容器的使用、二次回收使用,废弃物处理等包装的生命周期环节,对其能量消耗、环境影响等进行了评价。分析结果表明:纸铝塑复合包装的环境负荷主要体现在原材料的获取阶段,集中在燃料能源的消耗,其中纸材料加工的环境负荷要大于塑料与铝;填埋、焚烧、再利用这3种处置方式对环境的影响主要集中在化石燃料的消耗、土地占用和无机物对人体的损害上。因此,在维持现有结构的情况下,实行材料减量化和容器轻量化是提高包装环保适性最直接、有效的途径。