A systems analysis tool for construction and demolition wastes management

Managing construction and demolition (C&D) wastes has challenged many municipalities with diminishing waste disposal capacity. Facing such challenges, the Massachusetts Department of Environmental Protection proposed a policy restricting the landfill disposal of certain C&D waste materials, if unprocessed. This research is to study the potential economic impact of such restriction on construction contractors and C&D waste processors. A spreadsheet-based systems analysis model has been developed to assist the cost-benefit evaluation for various C&D waste management scenarios. The model, developed based on the mass balance principle, is designed to track a C&D waste stream through the various stages of a waste management system, i.e. generation, source separation, processing, recycling, and final disposal. This model, by incorporating the material flow data with the cost/revenue data associated with each management activity, can then provide an economic analysis for a proposed C&D waste management scenario. A case study illustrating the application of this model for Massachusetts is also presented.     

Evaluation of investments in recycling centres for construction and demolition wastes in Brazilian municipalities

There are very few construction and demolition (C&D) waste recycling centres in Brazil. To encourage the building and operation of new units, data were collected and analysed relating to C&D waste management and recycling in Brazil. Based on the results of this analysis, a conceptual model is presented for conducting viability studies of future C&D waste recycling centres. Applying this model to verify the viability of private recycling centres, the results show that under current market conditions in Brazil, C&D waste recycling centres are not financially feasible based solely on revenue from the sale of processed products. Nevertheless, under the same market conditions, the recycling centres could be economically viable for public authorities depending on the particular circumstances of each municipality. The feasibility, however, depends on continuity and the production volume reached. The conceptual model, the results of its applications and the discussions about the experiences of existing centres can strongly support public authorities and private initiatives in their decision-making about investments in Brazil and in other developing countries.     

用循环经济的理念彻底治理污染

全球性的金融危机发生已有大半年了,以美国为首的发达国家的经济遭受了沉重打击。在全球化的今天,我国自然不能独善其身而不受影响。我们要以人为本,坚持科学发展观,树立循环经济理念,贯彻落实《循环经济促进法》,坚决保护环境,彻底治理污染,保证我国经济平稳较快地发展。     

A dynamic model for assessing the effects of management strategies on the reduction of construction and demolition waste

During the past few decades, construction and demolition (C&D) waste has received increasing attention from construction practitioners and researchers worldwide. A plethora of research regarding C&D waste management has been published in various academic journals. However, it has been determined that existing studies with respect to C&D waste reduction are mainly carried out from a static perspective, without considering the dynamic and interdependent nature of the whole waste reduction system. This might lead to misunderstanding about the actual effect of implementing any waste reduction strategies. Therefore, this research proposes a model that can serve as a decision support tool for projecting C&D waste reduction in line with the waste management situation of a given construction project, and more importantly, as a platform for simulating effects of various management strategies on C&D waste reduction. The research is conducted using system dynamics methodology, which is a systematic approach that deals with the complexity - interrelationships and dynamics - of any social, economic and managerial system. The dynamic model integrates major variables that affect C&D waste reduction. In this paper, seven causal loop diagrams that can deepen understanding about the feedback relationships underlying C&D waste reduction system are firstly presented. Then a stock-flow diagram is formulated by using software for system dynamics modeling. Finally, a case study is used to illustrate the validation and application of the proposed model. Results of the case study not only built confidence in the model so that it can be used for quantitative analysis, but also assessed and compared the effect of three designed policy scenarios on C&D waste reduction. One major contribution of this study is the development of a dynamic model for evaluating C&D waste reduction strategies under various scenarios, so that best management strategies could be identified before being implemented in practice.     

Construction and demolition waste management in Kosovo: a survey of challenges and opportunities on the road to circular economy

Managing Construction and demolition waste (CDW) is a severe and growing urban challenge, particularly in post-conflict countries. Though Kosovo has significantly rebuilt and developed after the Liberation War, these initiatives have accompanied suboptimal waste management. This research evaluates CDW management in Kosovo by assessing current practices and operations vis-a-vis the legal framework and EU requirements. It identifies instruments and policies capable of ameliorating gaps and proposes a more sustainable and circular CDW management system for Kosovo. Information was primarily collected during on-site visits to Pristina and the surroundings by a cohort of Urban Management Students from the Technische Universität Berlin, students from Kosovo, and the local office of the Gesellschaft für Internationale Zusammenarbeit, GIZ. The analysis identified gaps in Kosovo's CDW management and its observance and enforcement of existing CDW legislation, including an ambiguous licensing system impeding sustainable demolition, storage, and transport; the absence of approved CDW storage options leading to uncontrolled disposal; and an underdeveloped market for recycling and reuse, deterring stakeholders from further pursuit of circular practices. These gaps were compounded by poor recordkeeping, obscuring precise information on CDW streams. Possible instruments and incentives to support Kosovo's transition to a more sustainable CDW management system were then identified.

     

Comparison of batch leaching tests and influence of pH on the release of metals from construction and demolition wastes

Construction and demolition wastes are suitable for use in road construction. However, leaching characterization of recycled materials is required to determine their pollutant potential and the consequence of their application in different scenarios. The motivation of this paper is derived from the increasing use of different leaching test methods. In Europe, the confusion resulting from the wide variety of tests used to evaluate environmental properties of construction materials implies that an evaluation of the current practices and the attempt to consolidate the approaches are required.Two equilibrium-based leaching tests (the Dutch test and the European standard) were conducted to assess the environmental impact of four recycled aggregates. Three natural limestone aggregates were used as controls. Both tests measure the potential release of hazardous elements under extreme conditions using different leaching parameters (L/S ratio, pH value and contact time). The results proved that pH is the most relevant factor on the assessment of the differences between leaching methods due to its strong control on the pollutant release.To classify the materials according to their environmental effects, the concentration limit values of the metals imposed by Council Decision 2003/33/EC were used as a reference. The comparison allowed the classification of the recycled aggregates as inert wastes, with the exception of the MR-2 aggregate, which was classified as non-hazardous material.     

Correlation analysis between sulphate content and leaching of sulphates in recycled aggregates from construction and demolition wastes

In some recycled aggregates applications, such as component of new concrete or roads, the total content of soluble sulphates should be measured and controlled. Restrictions are usually motivated by the resistance or stability of the new structure, and in most cases, structural concerns can be remedied by the use of techniques such as sulphur-resistant cements. However, environmental risk assessment from recycling and reuse construction products is often forgotten. The purpose of this study is to analyse the content of soluble sulphate on eleven recycled aggregates and six samples prepared in laboratory by the addition of different gypsum percentages. As points of reference, two natural aggregates were tested. An analysis of the content of the leachable amount of heavy metals regulated by European regulation was included. As a result, the correlation between solubility and leachability data allow suggest a limiting gypsum amount of 4.4% on recycled aggregates. This limit satisfies EU Landfill Directive criteria, which is currently used as reference by public Spanish Government for recycled aggregates in construction works.     

汨罗市循环经济发展调研及其财税对策研究

以国家循环经济试点单位汨罗市的循环经济产业为研究样本,在对汨罗循环经济试点的现状、存在的问题和困难进行深入调研的基础上,从税收和财政政策的角度,提出了具体的税收政策建议和财政支持措施,从而推动汨罗发展循环经济.     

汩罗市循环经济发展调研及其财税对策研究(续)

(接上期) 4 汨罗发展循环经济面临的困难和问题 4.1 汨罗再生资源产业自身面临的困难和问题 (1)再生资源交易市场容量小,产业集群度低.     

基于生态效率的循环经济重点行业评估

以产业物质代谢模型和生态效率理论为基础,采用权重分析法对我国2009年38个重点行业的资源环境效率和经济效率进行了评估。研究表明：机械设备制造相关行业可作为我国产业结构调整优先发展的领域,化工、钢铁等重工业行业是我国循环经济的重点。     

Preliminary study for the management of construction and demolition waste

This paper refers to the management of the construction and demolition (C&D) waste since, according to the EU Waste Strategy, C&D waste is considered to be one of the priority waste streams and appropriate actions need to be taken with respect to its effective management. Initially, the paper presents the state-of-the-art of the problem of C&D waste, including the amount and composition of C&D waste in EU countries, differences in the characteristics of this waste stream depending on its origin, as well as collection and management practices that are applied. A methodology is described for the estimation of the quantities of the waste stream under examination, since in most cases quantitative primary data is not available. Next, the fundamentals for the development of an integrated scheme for the management of C&D waste are presented and discussed, such as appropriate demolition procedures and location of waste management (off-site waste management, on-site waste management, direct on-site recovery, centralized on-site recovery). Finally, taking into consideration all relevant parameters, alternative systems that could be applied for the management of the C&D waste are suggested.     

Construction demolition wastes, Waelz slag and MSWI bottom ash: a comparative technical analysis as material for road construction

The objective of the study is to analyze the technical suitability of using secondary materials from three waste flows (construction and demolition waste (CDW), Waelz slag and municipal solid waste incineration (MSWI) bottom ash), under the regulations and standards governing the use of materials for road construction. A detailed technical characterization of the materials was carried out according to Spanish General Technical Specifications for Road Construction (PG3). The results show that Waelz slag can be adequate for using in granular structural layers, while CDW fits better as granular material in roadbeds. Likewise, fresh MSWI bottom ash can be used as roadbed material as long as it does not contain a high concentration of soluble salts. This paper also discusses the adequacy of using certain traditional test methods for natural soils when characterizing secondary materials for use as aggregates in road construction.     

Emergy analysis of the recycling options for construction and demolition waste

Construction and demolition (C&D) waste is becoming a major contributor to environmental pollution. In Shanghai, China, the quantity of C&D waste is 2.11E+07 t/yr, which accounts for 45% of the total quantity of solid waste. There has been a growing promotion of recycling C&D waste as an effective way to solve this waste problem. However, the evaluation of the efficiency of recycling C&D waste as a potential source of resources is largely based on traditional economic analysis. The economic analysis emphasizes money instead of the harmony between economic benefit and environmental effects. There is a need for a new strategic approach to investigate the efficiency of recycling C&D waste to achieve the integration between economic, social and environmental effects. Emergy theory can be employed to analyze different recycling options for C&D waste. With reference to the Chinese construction industry, this paper demonstrates that the close-loop recycling option is better than the open-loop recycling option for C&D waste in terms of the integration of social, environmental and sustainable aspects. To evaluate different technology solutions for C&D waste recycling, the emergy theory and method is not limited to a cost-benefit balance but can include economic, social, environmental and sustainable effects.     

从美、德、日3国铅工业的特点看我国发展循环经济的重要性

作为对人体有害的金属铅,其生产、消费和再生受到世界各国,特别是美国、德国和日本等发达国家的重视.从分析世界铅的生产和消费入手,指出含铅废料(主要是电池)回收及铅再生的重要性;着重介绍了美、德、日3国废铅酸蓄电池的回收、铅再生产业的现状和特点;通过分析与研究我国铅工业目前存在的问题,指出我国发展循环经济的重要意义,并对如何发展循环经济提出建议.     

A review of waste prevention through 3R under the concept of circular economy in China

The large waste generation has become one of the worldwide environmental problems. Circular economy has been seen as a way to tackle its urgent problems of environmental degradation and source scarcity. In recent years, under the concepts of circular economy, waste prevention through “Reduce, Reuse and Recycle” (3R) rules have attracted a broad concern in China. China has made some great achievements on waste management, and at the same time is facing many challenges. It is very necessary to share the management experiences and practices with the scholars and managers in other countries. This review covered the current situation and progress of circular economy development from the perspective of the legal regime and project practices, and the recycling practices of typical waste. The typical household wastes, including municipal solid wastes (MSW), e-waste, and end of life vehicles (ELV), were studied as the typical cases. Based on an examination of the statistical results, we also identified the potential problems and challenges for waste prevention through 3R in China. Finally, we provided some effective measures to further improve the waste management and recycling in China.     

基于生命周期的干电池回收及其循环经济模型

介绍了产品全生命周期和循环经济的概念,提出了产品的资源循环模型.对干电池全生命周期的生命过程及阶段进行了划分,并分析了干电池的材料组成,提出了可应用于实践的干电池回收循环利用模型,计算出3种类型回收材料各自所占比重,为我国干电池回收业提供了决策理论和实践指导.     

基于沼气综合利用的乳业循环经济模式探讨与实践

为了解决乳业快速发展带来的环境污染和资源浪费问题,运用循环经济理论,分析探讨乳业循环经济模式,以镇江市长江乳业有限公司为例,建立"奶牛-沼气-种植-奶牛"的良性生态循环经济模式,企业的年运行效益为24.51万元,静态投资回收期为7.7年.研究结果对于实现乳业可持续发展,为相关企业节能减排,提高效益,探索畜禽粪便资源化利用的技术途径,建设乳业循环经济模式提供了参考.     

基于熵值法新疆循环经济发展综合评价分析

根据循环经济理论,针对新疆循环经济的发展,从资源可承载能力、环境发展、社会经济发展三个方面考虑建立新疆循环经济发展的综合评价指标体系,运用熵值法对新疆10年循环经济的发展水平进行综合评价,进而提出了相应的措施,包括完善法律法规体系、加快产业结构调整、加大政策鼓励力度、促进产业集聚等.     

按照循环经济发展理念建设宁东能源化工基地

宁东能源化工基地被列为国家13个规划建设的特大型煤炭基地之一,是全国能源基地的重要组成部分.介绍了宁东能源化工基地开发总体规划的基本情况,提出规化建设过程中存在的问题,并针对这些问题,提出具体的改进建议.