Modelling and analysis of a symbiotic waste management system

A municipal solid waste management system is symbiotic when there exists physical exchange of material or by-products between different treatment units. We propose a mathematical model for studying the interactive behaviour of different waste treatment operators in a symbiotic environment. Each operator is a self-interested entity, who sets his gate fee charge to maximise his own payoff. We study the properties and gate fee strategies of the operators, and also perform sensitivity analysis on various model parameters to discuss the local operator behaviour and the effects of various intervention strategies. We also propose a numerical algorithm to solve the model, yielding the optimal equilibrium gate fee charges, payoff and market share levels of different operators. Finally, computational studies based on a two-unit scenario in a case study of organic waste recycling is performed to demonstrate the interactive and dynamic behaviours of different operators. Our results strongly suggest that, to improve new treatment technology utilisation, subsidising the operating cost of the new treatment unit is more effective in the long-run than exerting control on the gate fee upper bounds of the operators by the system regulator. Furthermore, providing residual post-treatment discounts for treatment units can benefit the service users, rather than the waste treatment operators.     

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。     

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.     

Modification of MSW fly ash by anionic chelating surfactant

This paper elucidates a study on the re-utilization and stabilization of municipal solid waste (MSW) fly ash in producing a high value-added product by the surface modification of anionic chelating surfactant on the particles. After modification, MSW fly ash can be expected using as a filler of ultra-high molecular weight polymers. The effects of anionic chelating surfactants (ACS) on surface modification of MSW fly ash and fixing capacity for heavy metals were explored. Meanwhile, the interaction mechanism between surfactants and MSW fly ash was suggested. The results showed that anionic chelating surfactants can be used to effectively modify MSW fly ash particles and achieve a high active ratio. At the same time, they also exhibited a strong fixing capacity for heavy metals. Of the two modified MSW fly ash, ED3A-modified MSW fly ash has a much higher active ratio than MAP-modified MSW fly ash at over 95%, although its fixing capacity for heavy metals was a shade lower than MAP-modified MSW fly ash.     

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     

城市生活垃圾压缩设备的压头及箱体设计与分析

 针对目前城市生活垃圾压缩设备普遍存在压缩效果不够理想的问题,提出一种新型压头和箱体结构,给出一种压缩效果和密闭性较好的城市生活垃圾压缩方式．通过优化传统垃圾压缩设备压头的结构,设计一种推铲形新型压头装置,提高垃圾压缩设备的压缩倍数,改善垃圾的压缩效果．对现有压缩设备箱体的结构和污水排放口进行了改进,设计一种与推铲形压头相匹配的垃圾压缩设备新型箱体．采用有限元分析方法,对设计的推铲形压头装置和箱体进行了分析．分析结果表明,同目前垃圾压缩设备使用的平压头和楔形压头相比较,设计的推铲形压头具有更好的压缩效果,为城市生活垃圾压缩设备压缩装置的设计和制造提供了理论基础．     

In search of a reliable technique for the determination of the biological stability of the organic matter in the mechanical-biological treated waste

The biological stability determines the extent to which readily biodegradable organic matter has decomposed. In this work, a massive estimation of indices suitable for the measurement of biological stability of the organic matter content in solid waste samples has been carried out. Samples from different stages in a mechanical-biological treatment (MBT) plant treating municipal solid wastes (MSW) were selected as examples of different stages of organic matter stability in waste biological treatment. Aerobic indices based on respiration techniques properly reflected the process of organic matter biodegradation. Static and dynamic respirometry showed similar values in terms of aerobic biological activity (expressed as oxygen uptake rate, OUR), whereas cumulative oxygen consumption was a reliable method to express the biological stability of organic matter in solid samples. Methods based on OUR and cumulative oxygen consumption were positively correlated. Anaerobic methods based on biogas production (BP) tests also reflected well the degree of biological stability, although significant differences were found in solid and liquid BP assays. A significant correlation was found between cumulative oxygen consumption and ultimate biogas production. The results obtained in this study can be a basis for the quantitative measurement of the efficiency in the stabilization of organic matter in waste treatment plants, including MBT plants, anaerobic digestion of MSW and composting plants.     

Municipal solid waste management and greenhouse gas emission control through an inexact optimization model under interval and random uncertainties

Rapid increases in the amounts of untreated municipal solid waste (MSW) and discharged greenhouse gases (GHGs) from waste treatment processes have caused great challenges to urban development and environmental protection. This study aimed to develop an integrated interval-stochastic optimization model to support regional MSW management in China, where the parameters which show large variations were expressed as birandom variables, whereas the parameters with small fluctuation were assumed to be interval numbers. The main objective of this optimization model was to minimize the total cost with simultaneous considerations of MSW treatment and GHG control requirements. The stochastic equilibrium-based chance constrained programming technique and interactive two-step algorithms were used to solve this model. Among many types of solutions with various constraint-violation levels, the solutions with balanced characteristics were recommended as the decision basis. Compared with existing management schemes, the model solutions showed advantages in cost reduction and climate-change impact mitigation.     

Optimization of municipal solid waste leaching test procedure: assessment of the part of hydrosoluble organic compounds

Despite national recycling campaigns, the amount of municipal solid waste (MSW) to be treated remains very important in France with almost 39% of the waste produced going to landfills. Therefore with the increasing concern over sustainable development and energy valorization, it seems essential to optimize current treatment methods and develop new preparation techniques of the waste. Nevertheless an important first step to take into account is to evaluate the waste using a different method than biogas production. In this perspective, the leaching test (LT) could be used as a tool to evaluate the ability of a waste to mobilize organic and mineral compounds. This research aims at optimizing a leaching test protocol mainly adapted to organic waste in order to be used on MSW to assess the fractions of both fast and slow mobilized organic matter. Several leaching tests have thus been implemented, optimized and compared in terms of accessible organic matter in the waste. Results have shown that the test conditions have a great influence on the mobilization of pollutants. The duration of the test affects mainly the quantity and quality of organic molecules extracted. The renewal of the eluent does not properly simulate the conditions of a landfill. The results would be used to assess the performance and the efficiency of new ways of waste pretreatment.     

A study of system characteristics in a manufacturing cell

Using a comprehensive simulation model, a number of important parameters relating to manufacturing cells are investigated. These include: (i) the proposal by Burbidge that ‘period batch control’ is more appropriate for group technology cells, (ii) the effects of different numbers of tool set-up types or part families, (iii) the comparative merits of a larger 18-machine cell and 3 parallel 6-machine cells and (iv) the effects of inter-operation transit time within cells. System performance obtained showed that, with an efficient scheduling rule, the smaller batches product better facility utilization and job throughput. The results also suggest that, expect for extremely small, restrictive cells (with one or two tool setup types), the addition of further part families does not cause a serious deterioration in the productivity of the cell. The larger cells were found to be more effective than the small cells placed in parallel in all the system performance characteristics recorded.     

废旧冰箱回收工厂设施布置设计的研究

分析了废旧冰箱回收处理现状,建立了废旧冰箱回收工艺路线,介绍了废旧冰箱回收工厂设施布置设计的一般方法和过程．采用系统布置法（sip）对废旧冰箱回收工厂总平面布置和车间布置进行了设计;利用时间Petri网对车间物流系统建模并给予优化,得出回收工厂详细布置图,并用E—Factory对该回收厂三维仿真．     

Membrane–sorption technology for reprocessing liquid radioactive waste from nuclear reactors

The need for developing liquid radioactive waste (LRW) reprocessing technologies oriented on autonomous reprocessing at research and production enterprises that are equipped with nuclear reactors and/or use radionuclides in the research and production activity is substantiated. Membrane–sorption technology of LRW reprocessing is suggested as a universal solution. An installation implementing this technology in the modular version, ensuring its low-cost transportation from one facility to another, is described. The developed modular membrane–sorption installation ensures efficient treatment of radioactively contaminated waters with the decontamination factor of 10³–10⁴, irrespective of the physicochemical forms of the radionuclides (ionic, colloidal, molecular), with obtaining LRW concentrates for the subsequent cementation.     

Optimization of the solidification/stabilization process of MSW fly ash in cementitious matrices

The solidification/stabilization (S/S) process of municipal solid waste (MSW) fly ash in cementitious matrices was investigated in order to ascertain the feasibility of a washing pretreatment of fly ash with water as a means of maximizing the ash content of cementitious mixtures. Four types of fly ash resulting from different Italian MSW incineration plants and ASTM Type III Portland cement were used in this study. Ash-cement mixtures with different fly ash/cement (FA/C) ratios were made using untreated and washed fly ash. Washing of fly ash with water was realized by a two-stage treatment (liquid/solid=25; mixing time=15 min for each stage). The cementitious mixtures were characterized for water demand, setting time, mechanical strength, and heavy metals leachability. Comparison between the above properties of mixtures incorporating untreated and washed fly ash (particularly, setting characteristics), coupled with economical evaluation of the S/S process when applied to untreated and washed fly ash, proved the feasibility of washing pretreatment as a means of maximizing the incorporation of MSW fly ash in cementitious matrices (ash content up to 75%-90% by weight of total solid).     

低温法小型空分设备:技术进步、与液体输送的竞争和对策

统计了我国空分行业历年已生产的 80 0m3 /h (O2 )以下小型空分设备的数量。介绍了10多年来小型空分设备的技术进步 ,特别是低能耗小空分设备的出现。统计了各种液氧生产方法的制氧单位电耗。分析了低温法小型空分设备与液体输送单位氧气的成本比较 ,并讨论了低温法小型空分设备在与液体输送的市场竞争中如何取胜的对策。     

Persistent pollutants emission abatement in waste-to-energy systems

The paper is focused on analyzing methods, which enable a substantial reduction of persistent organic pollutants (POP) emissions to meet the environmental limits. Technologies based on adsorption of harmful compounds using activated carbon, technologies DeNOx/DeDiox as well as technology of catalytic filtration using a special material REMEDIA D/F are considered and compared. The latter technology consists in using a bag-house with bags manufactured from a special material (two layers—membrane from expanded PTFE and felt with bound in catalyst) called REMEDIA, which has successfully been used for the removal of PCDD/F during recent period. An optimum design is based on the computational support concerning the bag-house. It is illustrated through an industrial application of the municipal solid waste (MSW) incinerator with capacity of 15 t/h (96.000 t/year) of waste treated which is operated as a waste-to-energy system. Based on the experience from operating this incineration plant it has been proved that even after more than 3 years operation the activity of filtration material was not decreased and efficiency of dioxins removal from flue gas ranges from 97 to 99%. These facts come from complex measurements where concentration of PCDD/F toxic congeners in both flue gas and separated flying ash was measured. We arrived at confirming expected assumptions that various congeners are not decomposed uniformly in the dioxin filter and the stage of their decomposition depends on their representation in the gas phase. It is strongly influenced by their molecular weight. Their results and experience contribute to further improving the system.     

Municipal solid waste compost application improves productivity, polyphenol content, and antioxidant capacity of Mesembryanthemum edule

Organic wastes were successfully used as soil amendment to improve agrosystems productivity. Yet, the effectiveness of this practice to enhance plant antioxidant capacities has received little attention. Here, we assess the effect of municipal solid waste (MSW) compost (at 40 t ha(-1)) on growth, polyphenol contents and antioxidant activities of Mesembryanthemum edule. MSW compost application significantly increased the soil contents of carbon, nitrogen, calcium, phosphorus and potassium. This was associated with higher nutrient (N, P, and K) uptake, which likely led to the significant improvement of the plant biomass and relative growth rate (RGR) (+93% on average) as compared to the control. In the same way, the fertilizing effect of the added organic matter significantly enhanced the antioxidant potential M. edule, assessed by radical scavenging activity, iron reducing power and β-carotene bleaching capacity. This was associated with significantly higher antioxidant contents, mainly total phenols and flavonoids. Heavy metal (Pb, Cd, Cu, and Zn) concentrations were slightly increased upon compost application, but remained lower than phytotoxic values. Overall, our results point out that short-term MSW compost application at 40 t ha(-1) is efficient in enhancing the productivity together with the antioxidant potentiality of M. edule without any adverse environmental impact.     

Evaluation of PCDD/Fs emission from fluidized bed incinerators co-firing MSW with coal in China

The levels and homologue profile of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from stack gas of three typical fluidized bed incinerators co-firing municipal solid waste (MSW) with Chinese coal were measured. The PCDD/Fs emission was in the range of 0.0054-0.1961 ng I-TEQ/N m(3). Comparison of PCDD/Fs detection results by HRGC/HRMS and HRGC/LRMS suggested that it was feasible to detect fly ash with high PCDD/Fs concentration by HRGC/LRMS. Several factors on PCDD/Fs emission were discussed. The primary reason for the lower PCDD/Fs emission was the inhibition mechanism of relatively high sulfur in feeding coal on PCDD/Fs formation. The emission results also showed that there was no directly correlation between PCDD/Fs levels and CO, O(2) and HCl concentration in flue gas. It was estimated that about 0.1034 g I-TEQ was annually emitted to atmosphere from the tested three MSW incinerators (total daily treatment capacity is 800 tonnes MSW).     

Sintering of MSW fly ash for reuse as a concrete aggregate

The sintering process of municipal solid waste (MSW) fly ash was investigated in order to manufacture sintered products for reuse as concrete aggregates.Four types of fly ash resulting from different Italian MSW incineration plants were tested in this study. A modification of the chemical composition of MSW fly ash--through a preliminary four-stage washing treatment of this material with water--was attempted to improve the chemical and mechanical characteristics of sintered products.The sintering treatment of untreated or washed fly ash was performed on cylindrical compact specimens (15 mm in diameter and 20mm in height) at different compact pressures, sintering temperatures and times.The sintering process of untreated MSW fly ashes proved to be ineffective for manufacturing sintered products for reuse as a construction material, because of the adverse chemical characteristics of these fly ashes in terms of sulfate, chloride, and vitrifying oxide contents.A preliminary washing treatment of MSW fly ash with water greatly improved the chemical and mechanical characteristics of sintered products and, for all the types of fly ash tested, the sintered products satisfied the Italian requirements for normal weight aggregates for use in concretes having a specified strength not greater than 12 and 15N/mm(2), when measured on cylindrical and cubic specimens, respectively.A compact pressure of 28 N/mm(2), a sintering temperature of 1140 degrees C, and a sintering time of 60 min were the best operating conditions for manufacturing sintered products of washed MSW fly ash.     

城市生活垃圾的工程特性及填埋场的岩土工程问题

填埋法是目前处理城市固体废弃物(MSW)的主要方法。从沉降、稳定、渗透、扩散四个方面分析了在城市固体废弃物填埋场中存在的问题。总结了国内外城市固体废弃物的工程特性,并给出了浙江大学岩土工程研究所对杭州市某填埋场的固体废弃物试样进行室内和现场试验的结果。填埋体的工程性质与其组成成分、填埋方式、环境条件有关、并随不同地点及时间有关。由于MSW工程性质的复杂性,这里所给出的各个工程指标仅供参考使用,对于在正式进行填埋场设计时,还需根据当地固体废弃物进行专门试验。     

Research output analysis of municipal solid waste: a case study of China

Municipal solid waste (MSW) management in China draws particular attention as China has become the largest MSW generator in the world. The paper analyzed the growth and development of MSW research productivity in China in terms of publication output as reflected in science citation index for the period 1997–2011. The study revealed that the output of MSW research in China has rapidly increased over the 15 years in contrast with USA. Chinese authors contributed 730 publications out of which 708 were journal articles, 17 reviews, 3 editorial materials, 1 correction and 1 meeting abstract, from 421 institutions. About 13.70 % of publications were contributed by Chinese Academy of Sciences, followed by Tongji University, Shanghai (13.15) and Tsinghua University, Beijing (11.10 %). That impact factors of the top 20 journals publishing most papers were between 0.30 and 4.63. Leading 20 authors in the area of MSW research published at least 13 articles per person. The annual share of publications varied from 0.27 to 20.96 % per year. The share was highest in the year 2009 at 20.96 %. An analysis of the title-words showed that “landfill”, “incineration” and “management” were recent major topics of municipal solid waste research in China. The results could help researchers understand the characteristics of research output and search hot spots of MSW field in China.