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     

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.     

风力发电复合材料叶片废弃物的几种处理方法分析

在简述风电叶片发展历史同时,对叶片制造特点及其相关废弃物来源、后期数量、处理必要性与可行性等进行了详细阐述。随后根据风力发电复合材料叶片废弃物相关特点等,从环境影响、处理费用、处理所得物用途三方面,对物理粉碎法、材料再循环与能量回收结合法、水泥制造法、焚烧热能法四种可能处理方法进行了深入分析;分析得出因废弃物本身及处理后可替代物价值较低,进而致使处理时环境效益或有一定优势,但经济效益不理想。最后根据该类废弃物特点及处理分析结论,并结合我国实际情况,建议后期优先发展水泥制造法,适时适地适当发展焚烧热能法、物理粉碎法。     

聚合物基碳纤维复合材料废弃物的几种处理方法分析

从环保和可持续发展角度出发,并结合我国碳纤维(CF)生产与使用实际情况,对聚合物基碳纤维复合材料(CFRP)废弃物处理必要性作了较为详尽的阐述。根据CFRP废弃物种类,提出了机械材料再循环法、材料再循环与能量回收法、能量回收焚烧法三种可行处理方法,并从处理费用、环境影响、替代用途三方面对多种处理方案进行了合理评估。综合考虑处理环境影响、经济效益及替代物使用性能等因素,材料再循环与能量回收法为处理CFRP废弃物最合适的方法。此外,为推进其后期处理工作的顺利进行,还从内部、外部因素两方面提出相关建议。     

Waste-to-energy is compatible and complementary with recycling in the circular economy

Clean Technologies and Environmental Policy - This paper reviews the role of conventional waste-to-energy, i.e. incineration of (mainly) municipal solid waste with energy recovery, in the circular...     

Metallurgical recovery of metals from electronic waste: a review

Waste electric and electronic equipment, or electronic waste, has been taken into consideration not only by the government but also by the public due to their hazardous material contents. In the detailed literature survey, value distributions for different electronic waste samples were calculated. It is showed that the major economic driver for recycling of electronic waste is from the recovery of precious metals. The state of the art in recovery of precious metals from electronic waste by pyrometallurgical processing, hydrometallurgical processing, and biometallurgical processing are highlighted in the paper. Pyrometallurgical processing has been a traditional technology for recovery of precious metals from waste electronic equipment. However, state-of-the-art smelters are highly depended on investments. Recent research on recovery of energy from PC waste gives an example for using plastics in this waste stream. It indicates that thermal processing provides a feasible approach for recovery of energy from electronic waste if a comprehensive emission control system is installed. In the last decade, attentions have been removed from pyrometallurgical process to hydrometallurgical process for recovery of metals from electronic waste. In the paper, hydrometallurgical processing techniques including cyanide leaching, halide leaching, thiourea leaching, and thiosulfate leaching of precious metals are detailed. In order to develop an environmentally friendly technique for recovery of precious metals from electronic scrap, a critical comparison of main leaching methods is analyzed for both economic feasibility and environmental impact. It is believed that biotechnology has been one of the most promising technologies in metallurgical processing. Bioleaching has been used for recovery of precious metals and copper from ores for many years. However, limited research was carried out on the bioleaching of metals from electronic waste. In the review, initial researches on the topic are presented. In addition, mechanisms and models of biosorption of precious metal ions from solutions are discussed.     

Bury,burn, or gasify: assessing municipal solid waste management options in Indian megacities by exergy analysis

With increasing consumption propelled by economic prosperity, waste generation per capita in developing countries is growing quickly. Traditional approaches of open dumping and landfilling are encountering physical constraints, particularly in megacities, and the need for alternate municipal solid waste (MSW) management strategies is urgent. Among alternatives that are commonly considered are waste-to-energy technologies including incineration and plasma gasification. Previous studies convey the benefits of such technologies, but most do not consider the waste and environmental conditions in tropical megacities such as Mumbai, India, making these studies of limited use to developing countries. This article evaluates the exergetic potential of converting MSW to useful work by thermal and biochemical conversion technologies in the Indian context, considering the facts that the scale of production, composition, climate, segregation practices, moisture content of MSW, etc. in a developing tropical country like India differ significantly from those in developed societies in temperate climate locations. Both, exergy and economic analysis find gasification to be attractive in terms of its monetary return and thermodynamic efficiency. However, this analysis also identifies major hurdles in adopting advanced waste-to-energy technologies including lack of waste segregation, high moisture content, and high capital cost of the most thermodynamically efficient technology.     

沼气机压缩式热泵系统的构建与经济性分析

由沼气发动机驱动的热泵（BHP）除能够保证一般热泵功能外,还能够充分回收利用沼气发动机的余热。根据对BHP的系统构建及一次能源利用率（PER）的计算结果,分析BHP系统的经济性及其对环境保护的作用。结果表明：BHP系统在经济性及环保方面都具有明显的经济价值和现实意义。     

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.     

Logistic model-based tool for policy-making towards sustainable waste management

The aim of this paper is to introduce a novel approach which supports facility planning in the field of waste management. Only 23 % of municipal solid waste (MSW) was thermally treated in the EU 27 in 2011. The increased exploitation of its potential for energy recovery must be accompanied by massive investments into highly efficient and reliable incineration technologies. Therefore, the challenge is to be efficient and use the technology to its optimal level. Feasibility studies of all plants providing a service for a region create a large and complex task. Gate fee (the charge for waste processing in the facility) represents one of the most crucial input parameters for the assessment. The gate fee is driven by configuration of the technology, competition, market development, environmental taxation and costs of waste transport to satisfy the plant’s capacity. Valid prediction of the gate fee thus presents a demanding task. In this paper, first, an advanced tool called NERUDA is introduced, which addresses logistic optimization and capacity sizing. The key idea is to focus on the problem of competition modelling among waste-to-energy plants, landfill sites, and mechanical–biological treatment plants producing refuse-derived fuel. Then, the main theoretical concepts are discussed, followed by the development of a suitable mathematical model. The goal is to obtain a minimized cost of MSW treatment for waste producers (municipalities). The application of the developed tool is demonstrated through a case study, where uncertain parameters entering the calculation are handled by a repetitive Monte Carlo simulation based on real-world data.     

Thermal plasma technology for the treatment of wastes: a critical review

This review describes the current status of waste treatment using thermal plasma technology. A comprehensive analysis of the available scientific and technical literature on waste plasma treatment is presented, including the treatment of a variety of hazardous wastes, such as residues from municipal solid waste incineration, slag and dust from steel production, asbestos-containing wastes, health care wastes and organic liquid wastes. The principles of thermal plasma generation and the technologies available are outlined, together with potential applications for plasma vitrified products. There have been continued advances in the application of plasma technology for waste treatment, and this is now a viable alternative to other potential treatment/disposal options. Regulatory, economic and socio-political drivers are promoting adoption of advanced thermal conversion techniques such as thermal plasma technology and these are expected to become increasingly commercially viable in the future.     

Production of green energy from co-digestion: perspectives for the Province of Cuneo, energetic balance and environmental sustainability

In Italy and many European countries, energy production from biomass is encouraged by strong economic subsidies so that biomass energy plants are getting large diffusion. Nevertheless, it is necessary to define the environmental compatibility taking into account global parameters as well as environmental impacts at regional and local scales coming from new polluting emissions. The environmental balances regarding new energy plants are of primary importance within very polluted areas such as Northern Italy where air quality limits are systematically exceeded, in particular for PM₁₀, NO₂, and ozone. The paper analyzes the renewable energy scenario relating to manure anaerobic digestion and biogas production for the Province of Cuneo, N–W Italy, and the environmental sustainability of the possible choices. The study is focused on energy producibility, heat and power, nitrogen oxides and ammonia emissions, GHG (greenhouse gases) balances dealing also with indirect releases of CH₄ and N₂O, as well as emissions due to energy crops production. The most important conclusion that can be drawn is that the production of renewable energy from anaerobic digestion could cover up to 13 % of the Province electricity consumption, but sustainability in terms of CO₂ emissions can be reached only through an overriding use of agricultural waste products (manure and by-products instead of energy crops) and cogeneration of thermal energy at disposal; the application of the best available techniques to waste gas cleaning, energy recovery, and digestate chemical–physical treatments allows positive emissive balances.     

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.     

Hydrogen recovery from the thermal plasma gasification of solid waste

Thermal plasma gasification has been demonstrated as one of the most effective and environmentally friendly methods for solid waste treatment and energy utilization in many of studies. Therefore, the thermal plasma process of solid waste gasification (paper mill waste, 1.2 ton/day) was applied for the recovery of high purity H(2) (>99.99%). Gases emitted from a gasification furnace equipped with a nontransferred thermal plasma torch were purified using a bag-filter and wet scrubber. Thereafter, the gases, which contained syngas (CO+H(2)), were introduced into a H(2) recovery system, consisting largely of a water gas shift (WGS) unit for the conversion of CO to H(2) and a pressure swing adsorption (PSA) unit for the separation and purification of H(2). It was successfully demonstrated that the thermal plasma process of solid waste gasification, combined with the WGS and PSA, produced high purity H(2) (20 N m(3)/h (400 H(2)-Nm(3)/PMW-ton), up to 99.99%) using a plasma torch with 1.6 MWh/PMW-ton of electricity. The results presented here suggest that the thermal plasma process of solid waste gasification for the production of high purity H(2) may provide a new approach as a future energy infrastructure based on H(2).     

Hybrid absorption heat pump with ammonia/water mixture – Some design guidelines and district heating application

An ammonia/water mixture can be used as an efficient working fluid in industrial-type heat recovery heat pumps and heat transformers. Several configurations of such systems are possible depending on the availability of the waste (thermal) and primary (thermal or electrical) energy sources. This article presents the configurations, the main thermodynamic and hydraulic parameters, and some design guidelines and operating experiences of a medium-temperature, ammonia/water-based compression/re-sorption heat recovery system for district domestic hot water production. In-field experiments have proven the advantages of the concept and its applicability limits in a particular economical environment, while hot water was produced at 55 °C with industrial cooling water at 36 °C as a waste heat source.     

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.     

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.     

Co-landfilling of pretreated waste: disposal and management strategies at lab-scale

The present paper deals with the possible advantages that can be obtained by co-landfilling of municipal solid waste organic fraction (MSWOF) and bottom ash (BA) from the incineration of municipal solid waste. In particular, the aim of the research hereby presented is to check the effect exerted by different disposal (mixed or layered) and management strategies (anaerobic or semiaerobic conditions) for landfills in which MSWOF and BA are co-disposed. Three lab-scale reactors were set-up: the reactor A with mixed BA and MSWOF in anaerobic conditions, the reactor B with mixed BA and MSWOF in semiaerobic conditions, the reactor C with layered BA and MSWOF in anaerobic conditions. The results obtained showed that the aeration at the beginning of the experimental period for about 60 days led to a more rapid biodegradation of the organic matter and to an improved leachate quality in terms of both organic load and nitrogen content. Also a significant increase in the settling rate was observed at the end of the aeration phase. Therefore, the aerobic management can be advised as the most available strategy providing a more rapid biological and mechanical stabilization of the bulk waste. Otherwise, the disposal strategy did not exert any significant effect on the leachate characteristics; however, the layered configuration may be adopted in order to accelerate the main settlements.     

空气源热泵耦合太阳能及余热用于升压站供暖的研究

风电场、光伏发电站等工程的升压站,一般远离集中热源,冬季多采用“电暖气+热水器”的传统方案,能源利用效率低,增加了电能消耗,降低了项目收益。提出“空气源热泵耦合太阳能及余热”的供暖方案,为升压站提供了可靠的热源,并提高了能源利用效率,降低了运行费用。升压站内电气设备间有大量的40℃左右的排风,可以作为空气源热泵的低温热源,解决了空气源热泵低温时效率低的弊病;空气源热泵生产出热水,并设置太阳能热水器进一步提高水温满足供暖要求;设置单独的蓄热水箱适应供暖负荷变化并解决一部分生活热水需求。以北京某风电场工程为例,阐述了这一系统的优缺点以及推广的必要性和可行性。分析表明,在最冷时该系统仍可以高效、稳定的运行,投资回收期短,为寒冷地区空气源热泵的应用提供了参考依据。