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

Comparison of environmental impacts related to municipal solid waste and construction and demolition waste management and recycling in a Latin American developing city

Construction and demolition waste (CDW) and municipal solid waste (MSW) are the waste flows mostly generated at a global level. In developing countries, most of these waste streams are disposed of in open dumps. Policy-makers should be informed in which priorities should be established in order to improve the quality of the environment. The current research compares the environmental impacts generated by the MSW and CDW management system of La Paz (Bolivia). The aim is to evaluate (1) which environmental impact indicators are more important per waste flow and (2) if recycling can be considered a good option for mitigating such environmental footprint. A life cycle assessment (LCA) of the formal MSW management and the CDW mismanagement (i.e., open dumping) were conducted. The analysis of the management system (2019) is compared with future developments in recycling that counts with the support of an international cooperative project financed by the Italian cooperation. Results reported that, at a municipal level, CDW mismanagement contributes more than 60% to the freshwater aquatic ecotoxicity, which represents the most relevant impact generated by this waste stream. Recycling allows achieving avoided impacts higher than the ones produced for three of six environmental impacts, suggesting MSW and CDW recovery as an important option for preventing environmental degradation. The research is the first attempt to highlight the importance of organizing appropriate CDW management systems into an integrated waste management scheme for mitigating environmental impacts in developing cities.

Physical process to sort construction and demolition waste (C&DW) fines components using process water

Modern societies are generating considerable volume of Construction and Demolition Wastes (C&DW) annually. Most recycling facilities offers viable sorting and recycling options for the coarser particles of the different materials found in those wastes. However, usual dry mechanical sorting and human sorting are not efficient on C&DW fines particles (C&DF, <10 mm) representing the third of the C&DW produced and being composed of similar materials. Recent environmental issues related to the landfilling of C&DF have pointed out the need to develop innovative alternative and adapted recycling paths for the C&DF. This study presents an efficient sorting process train based on physical separation steps used in the mining and the soil treatment industries. The use and recirculation of process water allowed to segregate and concentrate the gypsum from the 2-12 mm C&DF into a specific fraction (55-65% gypsum content) representing 40% of the total mass. Other constituents were sorted based on their relative density, size and shapes; thanks to hydraulic classification and physical sorting forming four more fractions with high recycling potential: coarse aggregates (15%), fine aggregates (9.4%), organic and inorganic fibers (10.8%) and light organic compounds (24.8%). The process has been designed to be integrated in existing sorting facilities and the process costs were evaluated to 38 CAN$/t.

Evaluation of the Techno-Economic Feasibility for Excavated Soil Recycling in Shenzhen, China

The existing recycling chain of construction and demolition waste generally considers soil inert solid waste to be sent to landfills. As the most significant component of C&D (construction and demolition) waste, excavated soil occupies approximately half of landfills. Currently, excavated soil is a big issue in China’s Pearl River Delta. This paper investigated the composition and quantity of excavated soil in Shenzhen, China. In particular, the potential market demand for critical recycled sand (a key recycled material extracted from the excavated soil) was estimated. Furthermore, the technical analysis for excavated soil recycling takes an entire excavated soil recycling process’s perspective, delving into the process flow for the excavated soil and the recycled sand’s physicomechanical properties. Then, two mainstream and legitimate models of excavated soil recycling were considered: stationary plant recycling and on-site recycling. Each model’s financial and economic viability was assessed. The financial analysis focuses on investors’ perspectives, whose primary goal is to assess their investment profitability. The economic feasibility of the excavated soil stationary plant recycling and on-site recycling models in Shenzhen were then compared via benefit and cost analysis during the lifetime of the recycling equipment. A comprehensive, complete cost calculation and investment analysis revealed that Shenzhen’s excavated soil recycling business is profitable under the current market conditions. This study investigates scaled and effective excavated soil recycling and gives a technically and economically viable reference to the global excavated soil issue.

The urbanisation-environment conflict: Insights from material stock and productivity of transport infrastructure in Hanoi, Vietnam

Developing regions experience rapid population growth and urbanisation, which require large quantities of materials for civil infrastructure. The production of construction materials, especially for urban transport systems, however, contributes to local and global environmental change. Political agendas may overlook the environmental implications of urban expansion, as economic growth tends to be prioritised. While elevating the standard of living is imperative, decision-making without careful environmental assessments can undermine the overall welfare of society. In this study, we evaluate the material demand and in-use stock productivity for the large-scale development plan for transport infrastructure in the city of Hanoi, Vietnam, from 2010 to 2030, combining geospatial and socioeconomic data with statistics on roads and railways. The results show that the total material stock could rise threefold from 66 Tg in 2010 to 269 Tg in 2030, which roughly translates to an addition of 30 Empire State Buildings per year by mass. The materials we account are required for construction exceed the availability of local sand and will need to be gathered farther away. Furthermore, the material stock productivity of the transport infrastructure appears to have been declining overall since 2010, and this trend may continue to 2030. These findings demonstrate the importance of informing urban planning with a comprehensive assessment of construction materials demand, supply capacity, and environmental impacts. Policy priorities for improving the in-use stock productivity are also recommended towards achieving a more efficient utilisation of natural resources.

Characterization of Demolished Concretes with Three Different Strengths for Recycling as Coarse Aggregate

This paper presents a physical characterization for the recycling into new concretes of three comminuted concretes: C16/20 (“ordinary concrete”), C50/60 (“high strength concrete”), and C70/85 (“very high strength concrete”). The top size of the crushed concretes was 19.1 mm and the size range was 4.75 to 19.1 mm. The characterization was carried out with coarse aggregate liberation, to be prepared and concentrated in a gravity concentration process. The density distribution of the coarse aggregate, cement paste, and sand was carried out in different size ranges (4.75/19.1 mm; 4.75/8.0 mm; 8.0/12.5 mm; and 12.5/19.1 mm) for the three concretes studied. The form factor of the samples, as well as the porosity determination of particles in different density ranges, are presented. The obtained results indicate that the coarse aggregate liberation was more intensive for the low resistance concrete (C16/20), but a reasonable coarse aggregate recovery is possible for all concretes.

Decision-making interaction among stakeholders regarding construction and demolition waste recycling under different power structures

The market power and competition scenario of recycling enterprises and landfills may change in the future due to the environmental pressure caused by landfills and the environmental potential of construction and demolition waste (C&DW) recycling. In this context, how these changes will affect the economic performance of enterprises and the environmental performance of the whole society remains unclear, along with how the willingness to pay and the environmental awareness of contractors will affect the pricing decisions of recycling enterprises and landfills. This study investigates the charging and recycling problem under different power structures in the reverse supply chain of C&DW, which is composed of waste generators (construction contractors) and two disposers (recycling enterprises and landfills). The interactive decisions of three stakeholders are discussed and the optimal charge fee, profit, and recycling ratio are obtained. Results indicate the following (i) The environmental preference of contractors directly increases the charge fee of recycling enterprises, and indirectly increases the charge fee of landfills. (ii) An increase in contractors' environmental preference will reduce the recycling ratio of C&DW and increase landfill and illegal dumping ratios. (iii) From the perspective of environmental benefits, illegal dumping and recycling ratios experience the worst scenario in the Recycling-Stackelberg game model and the best scenario in Nash game model because recycling enterprises take advantage of their dominant market position and set higher charges than those that contractors can afford. This theoretical study bridges the research gap on the effects of the market power on the environmental and economic performance of stakeholders in the field of C&DW management. The findings also help policy makers understand the behavior of stakeholders under different power structures to formulate the most effective intervention strategies.

Financial and economic evaluation of construction and demolition waste recycling in Hanoi, Vietnam

Increasing waste generation and the absence of a formal recycling industry are exacerbating the inadequacy of Construction and Demolition Waste (CDW) management in Hanoi, Vietnam. This study assesses potential CDW recycling in Hanoi by estimating the prospective supply of and demand for CDW recycling plants and evaluating their likely costs and benefits. Supply of concrete waste was calculated based on the weight-per-construction-area method whilst demand for recycled concrete aggregates (RCA) was determined by estimating the amount of aggregates for road construction in Hanoi from 2013 to 2017. Two potential models of CDW recycling plants were considered: a stationary plant and a mobile plant, with capacities of 1,000 and 360 tons/day, respectively. Our findings reveal that demand for RCA exceeds waste concrete supply, suggesting a promising market for RCA. Positive Net Present Value and Internal Rate of Return values of the stationary plant indicate its feasibility as an investment option. Meanwhile, the introduction of mobile recycling plants might require governmental intervention to internalize recycling positive externalities. Supporting policies might include a combination of a virgin material tax, green public procurement, and quality standard development.

Developing efficient circularity for construction and demolition waste management in fast emerging economies: Lessons learned from Shenzhen, China

Proper management of construction and demolition (C&D) waste is a key challenge amid global advocacy of the circular economy. This is of particular urgency in fast-emerging economies, where economic development induces massive construction without the capacity to manage the associated waste. This paper reports lessons learned from Shenzhen, China, which has witnessed exciting economic growth in the past few decades but also been compelled to rapidly develop an effective C&D waste circular economy from a low base. The research adopts a mixed-method approach combining case study, site investigations, and interviews in Shenzhen. It is discovered that Shenzhen's success can be attributed to (a) implementing strong governmental interventions; (b) developing a thriving C&D waste recycling market; (c) introducing advanced recycling technologies; and (d) enacting responsive institutional arrangements. Further improvements related to (1) recycled product certification, (2) land use and economic subsidies, and (3) changing circular economy philosophies, inter alia, are desired to sustain the long-term prosperity of this circular economy. The research provides a reference which can be adapted to the unique context of other emerging economies in developing effective circularity.

Construction and demolition waste applications and maximum daily output in Spanish recycling plants

The pursuit of construction sustainability has driven the use of partially or wholly waste-based eco-materials. New applications are being sought for recycled aggregate (RA) to further the use of this material and ensure the survival of the construction and demolition waste (C&DW) industry. RA, currently used in the construction of pavements, fills and embankments and only incipiently to manufacture structural or non-structural concrete, is a mere 8.99% of the total aggregate extracted in EU countries where RA is produced. Against this backdrop, the utility of this study lies in the overview afforded of RA typology, the application of the product in bound or unbound materials, the pursuit of new applications, structural or otherwise, and the assessment of daily maximum output by C&DW recycling facilities in Spain. The findings show that irrespective of its origin, RA most commonly adopts the form of wet mix macadam, gravel or sand used primarily in unbound applications with only dubious quality standards. Plant managers contend that RA from clean waste can feasibly be used in bound applications that require higher-performance materials. Maximum daily output varies widely, with capacity under 200 t d^-1 in 30% of the plants. One of the conclusions drawn is that the current business model is in need of revision, with an emphasis on aggregate quality control (certification) and the adoption of technology for separating out impurities, pollutants and undesirable materials to improve the quality of RA.

Assessing the role and use of recycled aggregates in the sustainable management of construction and demolition waste via a mini-review and a case study

Rapid industrial development, mega construction projects and increased immigration are some of the reasons that the State of Qatar has recently generated an unprecedented amount of construction and demolition (C&D) waste in the country. The State is racing towards the Fédération Internationale de Football Association World Cup 2022, a fact that requires additional construction, for which it is expected to increase its rate of waste generation. Compared to other regions, there are relatively few studies in the literature that report on the C&D waste management issues of Qatar. The present work begins to address this gap by providing insights into the current state of C&D waste management practices in Qatar and by providing a mini-review on the benefits of using recycled aggregates which have only recently been allowed locally by Qatar Construction Standards. A Strengths, Weaknesses, Opportunities, and Threats analysis has been implemented, using data and information from various sources including governmental reports, industries, local waste management companies, as well as reported interviews with relevant stakeholders. Finally, several strategies were proposed and developed that could potentially be implemented by stakeholders and decision-makers, so as to improve the current status by encouraging more sustainable and viable practices.

Information-based quality management in reverse logistics supply chain

Purpose

The purpose of this paper is to explore the synergies among reverse logistics supply chain (RLSC), quality management (QM) and information management (IM) concepts to enhance the effectiveness of demolition waste management (DWM) practices.

Design/methodology/approach

A systematic literature review was conducted using 70 articles published between the years of 2006 and 2017, which were subjected to descriptive and thematic analysis.

Findings

The descriptive analysis established that the RLSC concept was dealt within the majority of the publications (61 per cent), followed by concepts related to quality in RLSC (24 per cent). Only 14 per cent of the articles were based on IM concepts related to RLSC. Quality and information are interrelated in the effective implementation of RLSC. The thematic analysis demonstrated that there is a need for using quality parameters in a regulatory environment in an information-based environment. Based on the findings, future research directions were developed.

Research limitations/implications

The study encourages researchers to identify novel directions by combining these three concepts. The study developed a future research agenda regarding use of building information modelling (BIM) for existing buildings under novel technologies; analysis of secondary market demand and supply; and assessment of cost and safety management with quality in a BIM-enabled environment.

Practical implications

The practical implications include the application of sustainable management principles based on stakeholders and the regulatory environment.

Originality/value

Integration of the three concepts is an emerging area. This integration developed a robust approach to achieve QM in RLSC operations under a sound information flow enabling the optimisation of DWM.

Framework for economic assessment of concrete waste management strategies

Unlike developing countries, most developed countries address the problem of construction and demolition wastes (CDW) accumulation. In Egypt, CDW recycling plants are minimal. This study is devoted to understanding the economic aspects of constructing and operating a construction and demolition concrete waste recycling plant in Egypt. This includes accounting for several factors such as location, design of the recycling plant, the equipment used, and the material entering and leaving the plant. This is followed by implementing a detailed economic viability analysis that assesses the savings resulted from recycling concrete waste to produce recycled aggregate. CDW recycling plants give rise to economic viability as they seem economically viable even in the absence of specific government policies. A comprehensive case study of an actual project in New Cairo City in Egypt is presented in order to demonstrate the process of CDW disposal and illustrate the practical features of the proposed model.

Managerial Areas of Construction and Demolition Waste: A Scientometric Review

In past decades, the massive generation of construction and demolition waste (CDW) was increasingly threatening the public environment and humanity health worldwide. A large amount of research has been devoted to the CDW from difference perspectives. However, few scholars have attempted to summarize and review the extant studies, especially in the managerial areas of CDW (MA-CDW). This paper fills this gap via a systematic and quantitative review in the CDW management field. Employing the scientometric analysis method, a total of 261 articles published from 2006 to 2018 were collected to construct the knowledge map and comprehensive framework for MA-CDW. Results show that the overall evolutionary trend of MA-CDW was from basic management concepts to internal and external challenges analysis, to organizational strategy and innovative management practices. The major MA-CDW knowledge domains were identified and summarized into four pillars, namely: (1) factor and challenge; (2) composition and quantification; (3) assessment and comparison; and (4) technology and method. Based on the trend, knowledge gaps and future research directions were found out and discussed. This study contributes to the existing MA-CDW knowledge by presenting a comprehensive knowledge framework. Furthermore, these findings can provide the researchers and practitioners with an in-depth understanding for the sustainable governance of CDW.

Productivity improvement in solid waste recycling centres through lean implementation aided by multi-criteria decision analysis

Purpose

The purpose of this paper is to investigate, through a comparative analysis, the applicability of lean manufacturing practices, such as value stream mapping (VSM), for productivity improvement in recycling centres (RCs) aided by multi-criteria decision analysis.

Design/methodology/approach

The study is carried out in five RCs that sort the municipal solid waste of Porto Alegre, one of the main cities in Brazil. Since all of the centres present their labour composed by poor communities’ members, cultural and social characteristics may represent an incremental challenge for lean implementation. Further, these centres are organised in cooperatives, in which decisions are taken through a participatory way and all their members are entitled to vote, undermining and retarding the decision-making process.

Findings

The integration of a multi-criteria decision-making tool to the lean practices enables the prioritisation of improvements, complementing the final stage of VSM. In particular, this contribution becomes especially important in cooperatives managed by community, where decisions are often complex and time-consuming. Finally, despite the increasing pressure for better performance of RCs, the existent mindset is still far from the private sector, where lean practices were conceived. Further, the findings suggest that, despite processes similarities, it is not feasible to declare the existence of a one-best practice to such scenario.

Originality/value

In theoretical terms, the authors demonstrate through a multi-case study the adequacy of analytic hierarchy process as a decision analysis tool complementary to the VSM, enabling a broader perspective about this subject. Concerning the practical contribution, the comprehension of the adaptation needs for lean practices implementation within the production context of solid waste RCs provides a framework with guidelines for this sector, when incorporating lean activities. Lean practitioners and eventual municipal authorities involved in improving productivity of community-managed RCs might benefit from this framework, since they will be able to emphasise the development of recommended and already tested lean practices that tend to improve their operational performance.

GIS-based planning system for managing the flow of construction and demolition waste in Brazil

The objective of this article was to plan a network for municipal management of construction and demolition waste in Brazil with the assistance of a geographic information system, using the city of Recife as a case study. The methodology was carried out in three stages. The first was to map the illegal construction and demolition of waste disposal points across Recife and classify the waste according to its recyclability. In sequence, a method for indicating suitable areas for installation of voluntary delivery points, for small waste generators, are presented. Finally, a method for indicating suitable areas for the installation of trans-shipment and waste sorting areas, developed for large generators, is presented. The results show that a geographic information system is an essential tool in the planning of municipal construction and demolition waste management, in order to facilitate the spatial analysis and control the generation, sorting, collection, transportation, and final destination of construction and demolition waste, increasing the rate of recovery and recycling of materials.

Downcycling versus recycling of construction and demolition waste: Combining LCA and LCC to support sustainable policy making

Urgent solutions are needed in Europe to deal with construction and demolition waste (CDW). EU policy has contributed to significantly reducing the amount of CDW going to landfill, but most of the effort has been put in downcycling practices. Therefore, further policies are needed to stimulate high-quality recycling of CDW. The present paper presents a combined life cycle assessment (LCA) and life cycle costing (LCC) methodologies to analyse the environmental and the economic drivers in four alternative CDW end-of-life scenarios in the region of Flanders, in Belgium. The four analysed alternatives are (i) landfilling, (ii) downcycling, (iii) advanced recycling and (iv) recycling after selective demolition. LCA results show that landiflling is the scenario having the highest environmental impacts in terms of person equivalent (PE), followed by downcycling and recycling (-36%) and recycling after selective demolition (-59%). The decrease in environmental impacts is mostly due to the avoided landfilling of CDW and the recovery of materials from selective demolition. LCC results indicate that landfilling is the scenario bearing the highest total economic costs. This is due to the high landfill tax in Flanders. The recycling after selective demolition bears the second highest cost. The increase of high-quality CDW recycling can significantly reduce the overall environmental impact of the system. Implementing a high landfill tax, increasing the gate fee to the recycling plant, and boosting the sales price of recycled aggregates are the most effective drivers to facilitate a transition towards a more sustainable CDW management system. The paper demonstrates that the combined LCA and LCC results can highlight the environmental and economic drivers in CDW management. The results of the combined analysis can help policymakers to promote the aspects contributing to sustainability and to limit the ones creating a barrier.

An economic analysis of the processing technologies in CDW recycling platforms

This paper proposes an economic analysis of three different types of processing in CDW (construction and demolition waste) recycling platforms, according to the sophistication of the processing technologies (current advanced, advanced and advanced sorting). The methodology that is adopted is in the economic evaluation concept of projects and is classified with a scoping study phase. In these contexts, three levels of CDW processing capabilities for recycling platforms are analyzed (100, 300 and 600 thousand tons per year). This article considers databases obtained from similar projects that have been published in the specialized literature; the data sources are primarily from the European continent. The paper shows that current advanced process has better economic performance, in terms of IRR, related to the other two processes. The IRR associated with advanced and advanced sorting processes could be raised by, (i) higher price of secondary primary material, and/or (ii) higher capacity of platforms, and/or (iii) higher sharing of secondary primary material in the total production. The first two points depend on the market conditions (prices and total quantity of CDW available) and (potential) fiscal or incentive policies. The last one depends on technological progress.

Forecasting of construction and demolition waste in Brazil

The objective of this article is to develop a computerised tool (software) that facilitates the analysis of strategies for waste management on construction sites through the use of indicators of construction and demolition waste generation. The development involved the following steps: knowledge acquisition, structuring the system, coding and system evaluation. The step of knowledge acquisition aims to provide subsidies for the representation of them through models. In the step of structuring the system, it was presented the structuring and formalisation of knowledge for the development of the system, and has two stages: the construction of the conceptual model and the subsequent instantiation of the model. The coding system aims to implement (code) the conceptual model developed in a model played by computer (digital). The results showed that the system is very useful and applicable in construction sites, helping to improve the quality of waste management, and creating a database that will support new research.

Pilot-based assessment of the economics of recycling construction demolition waste

The significant amount of waste generated from construction demolition has become a chronic problem in many developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) to serve as a decision support tool in countries suffering from the lack of national CDW management guidelines. The framework is then demonstrated through a case study in the city of Beirut, Lebanon, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis showed that in order for a facility to be feasible, a gate fee should be charged in the presence of a market for recycled aggregates. The results confirm the significance of instigating and implementing legislation to control illegal dumping, constructing, and managing engineered landfills, and establishing markets for recycled CDW.

A study on the attitudes and behavioural influence of construction waste management in occupied Palestinian territory

As a step towards comprehending what drives the management of construction waste in the occupied Palestinian territory, this paper quantifies construction waste generation and examines how the local contractors' waste management attitudes and behaviour are influenced. Collection of data was based on a survey, carried out in the southern part of the West Bank between April and May 2010. The survey targeted contractors who specialized in the construction of buildings. A logistic regression model was used to investigate the relationship between various attributes and the attitudes and behaviour that the local contractors demonstrate towards waste management. The results showed that during the construction of buildings, 17 to 81 kg of construction waste are generated per square metre of building floor. Although the area of a building is the key factor determining 74.8% of the variation of construction waste generation, the employment of labour-intensive techniques in the study area means that human factors such as the contractor's attitude and behaviour towards waste management, exert a key influence on waste generation. Attitudes towards the 3Rs of waste minimization and behaviour towards waste disposal are generally positive with smaller contractors exhibiting more positive attitudes and more satisfactory behaviour towards waste management. Overall, while contractors' behaviour towards waste sorting and disposal tends to be more satisfactory among contractors who are more conscious about the potential environmental impacts of construction waste, it was generally observed that in the absence of a regulatory framework, the voluntary attitudes and behaviour among the local contractors are mostly driven by direct economic considerations.

Construction and demolition waste as a source of PVC for recycling

Construction and demolition waste can contain considerable amounts of polyvinyl chloride (PVC). This paper describes a study of the recycling of PVC pipes collected from such waste materials. In a sorting facility for the specific disposal of construction and demolition waste, PVC was found to represent one-third of the plastics separated by workers. Pipes were sorted carefully to preclude any possible contamination by poly(ethylene terephthalate) (PET) found in the waste. The material was ground into two distinct particle sizes (final mesh of 12.7 and 8 mm), washed, dried and recycled. The average formulation of the pipes was determined based on ash content tests and used in the fabrication of a similar compound made mainly of virgin PVC. Samples of recycled pipes and of compound based on virgin material were subjected to tensile and impact tests and provided very similar results. These results are a good indication of the application potential of the recycled material and of the fact that longer grinding to obtain finer particles is not necessarily beneficial.

Characteristics of fine processed construction and demolition waste in Japan and method to obtain fines having low gypsum component and wood contents

A method to obtain processed residue from mixed construction and demolition waste (mixed C&D-W) - free from environmental pollutants - for deposition in landfill is discussed. In particular, additional sieving, the presence of gypsum board in mixed C&D-W at the first stage of manual presorting, and the color of processed residue were studied for the basic characterization of the different fractions. Considerable precautions should be taken to prevent leaching of hazardous substances, such as T-Hg, Pb, Cr(6+), As, and fluoride and its compounds, when processed residue, particularly in crushed fraction at an intermediate treatment facility, is used as construction material. A relatively high content of gypsum was noted in processed residue generated at demolition work compared to that generated at construction work in processed residue from mixed C&D-W in which the presence of gypsum board was observed at the first stage of manual presorting, and in white processed residue. Additional sieving for removal was ineffective because gypsum and wood have wide particle size distributions. To obtain processed residue having low gypsum and wood contents, white processed residue should be removed to eliminate gypsum (content, 59% of initial sample), and brown or brown and yellow processed residue should be removed to eliminate wood (content, 32% of initial sample) without mixing with processed residue containing other colors at stockyards. The removed residue should be deposited in a controlled-type landfill site.