A model for cost-benefit analysis of construction and demolition waste management throughout the waste chain

Economic instrument is indubitably perceived as effective for encouraging or forcing contractors to conduct environmentally friendly construction practices. Previous studies in relation to this topic mainly put emphasis on economic analysis of construction and demolition (C&D) waste management from a static point of view, which failed to consider its dynamics nature by integrating all essential activities throughout the waste chain. This paper is thus intended to highlight the dynamics and interrelationships of C&D waste management practices and analyze the cost-benefit of this process using a system dynamics approach. Data related to concrete and aggregate of a construction project in Shenzhen was collected for the application of the proposed model. The findings reveal that net benefits from conducting C&D waste management will occur, but a higher landfill charge will lead to a higher net benefit, as well as an earlier realization of the net benefit. In addition, the general public under a higher landfill charge will suffer from a higher environmental cost caused by illegal dumping. The simulation results also suggest that current regulation in Shenzhen should be promoted to facilitate a dramatic increase in net benefit from the implementation of C&D waste management. This research is of value in facilitating better understanding on the dynamics of C&D waste management activities throughout the waste chain, as well as providing a tool for simulating the cost-benefit of C&D waste management practices over the project duration.     

Best practice measures assessment for construction and demolition waste management in building constructions

Currently the construction and demolition (C&D) waste collection system in Spain is managed in a decentralized manner by each sub-contracted company. This lack of comprehensive strategy for C&D waste management causes a confusing and sometimes individual attitude regarding the different measures for C&D waste. Therefore effective waste management should be enforced. Construction stakeholders have wide range of best practices in C&D waste management that can be implemented, so they need to be assessed for their effectiveness.The aim of this research study is to assist construction stakeholders in making a decision on C&D waste management. This paper carries out a survey conducted among the construction agents in order to evaluate the effectiveness of 20 best practice measures regarding C&D waste management, identifying the most suitable types of building constructions to implement these practices and also the advantages and drawbacks of their performance in a building construction project.Results of this study show that among the highly effective best practices are: the use of industrialized systems and the contract of suppliers managing the waste. In addition, distributing small containers in the work areas is also another high valued practice, although only 36% of respondents usually implement this measure in their works.     

Analysis of the implementation of effective waste management practices in construction projects and sites

In this paper, the implementation of effective waste management practices in construction projects and sites is analyzed, using data from a survey answered by 74 Spanish construction companies based in Catalonia. Most commonly implemented practices were found to be on-site cleanliness and order, correct storage of raw materials, and prioritization of the nearest authorized waste managers. The least widespread practices were the use of a mobile crusher on site, the creation of individualized drawings for each construction site, and the dissemination of the contents of the waste management plan to all workers, to help them to meet its requirements. Waste regulations for construction and demolition, and the corresponding construction waste management facilities, were designed before the recession in the Spanish construction sector. Current waste generation rates are still below predicted levels, and the infrastructure was designed for five times more waste generation. Even so, the percentage of reused and recycled waste currently amounts to 43%. Survey respondents highlighted various instruments and measures that would make the management of construction and demolition waste more sustainable. Most of the opportunities identified by construction firms are within the scope of government and related to a combined system of bonus and penalties and the establishment of environmental awareness and training programmes for all the stakeholders. Within the scope of authorized waste managers, firms suggested improvements such as the standardization of fees, a reduction of the time until the issue of waste management certificates, a higher number of inspections, and a change in the current model of a few large construction waste management facilities. This research is useful to better understand the current status of construction and demolition waste management in construction projects and sites. Thus, the results of this research will guide policy makers and relevant stakeholders such as contractors, clients, architects and engineers to achieve the EU target of recovering 70% of construction and demolition waste in 2020. In this sense, reliable information can help governments and professional associations to set future C&D waste management regulations, training programmes and dissemination tools, inspections, etc.     

Assessing the accumulation of construction waste generation during residential building construction works

The difficulty of dealing with construction and demolition waste (CDW) on construction sites is not new and continues to be an environmental problem. Understanding the waste generated in a construction work is essential to optimize CDW management. Therefore, any tool used for establishing an estimation of the CDW that will be generated should be considered as an alternative to achieve real solutions pursuing sustainability. This paper presents the evolution of CDW flow generation in the construction of new residential buildings, and has identified that the construction activity is increasing the waste generation. In an attempt to find some solutions and provide improved alternatives, several building sites have been analysed in order to quantify the estimation of CDW generated. Results show that when using plasterboard walls the CDW generation, per m² of built surface can be reduced up to 15.94% compared to the use of traditional brick partitions. In addition, a model describing the accumulation of CDW throughout the project duration is proposed. This model states that CDW mainly accumulates in the middle stages of the project. This study allows an estimation of the amount of CDW to be generated in a building construction site, helping to plan the number and size of containers required at any moment of the construction process, as well as the space required for a proper CDW management.     

Municipal solid waste generation in Kathmandu, Nepal

Waste stream characteristics must be understood to tackle waste management problems in Kathmandu Metropolitan City (KMC), Nepal. Three-stage stratified cluster sampling was used to evaluate solid waste data collected from 336 households in KMC. This information was combined with data collected regarding waste from restaurants, hotels, schools and streets. The study found that 497.3 g capita(-1) day(-1) of solid waste was generated from households and 48.5, 113.3 and 26.1 kg facility(-1) day(-1) of waste was generated from restaurants, hotels and schools, respectively. Street litter measured 69.3 metric tons day(-1). The average municipal solid waste generation rate was 523.8 metric tons day(-1) or 0.66 kg capita(-1) day(-1) as compared to the 320 metric tons day(-1) reported by the city. The coefficient of correlation between the number of people and the amount of waste produced was 0.94. Key household waste constituents included 71% organic wastes, 12% plastics, 7.5% paper and paper products, 5% dirt and construction debris and 1% hazardous wastes. Although the waste composition varied depending on the source, the composition analysis of waste from restaurants, hotels, schools and streets showed a high percentage of organic wastes. These numbers suggest a greater potential for recovery of organic wastes via composting and there is an opportunity for recycling. Because there is no previous inquiry of this scale in reporting comprehensive municipal solid waste generation in Nepal, this study can be treated as a baseline for other Nepalese municipalities.     

Waste minimisation in practice

One of the major hindrances to waste minimisation on a construction site is the difficulty in establishing a methodology and using this methodology to benchmark future construction projects. This paper introduces SMARTWaste, a software tool that has been used to audit, reduce and target waste arisings on a construction site. This tool tries to link the construction process and the waste hierarchy. That is reducing waste on a construction site rather than landfilling it. Three applications of the SMARTWaste software will be discussed using case studies from three different types of construction. An evaluation of these case studies shows that, by implementing a waste minimisation scheme on-site, you can improve material recovery for reuse. Also, by using the waste arisings as a benchmark you can reduce your waste arisings on future sites. Application of SMARTWaste or a similar waste minimisation tool on a wider basis could reduce waste arisings and could result in a built environment that consumed less natural resources and energy, and also produced less pollution and waste. Such a built environment would be environmentally and socially more responsive and responsible.     

An overview of waste materials recycling in the Sultanate of Oman

Various wastes and by-product materials are generated in the Sultanate of Oman including reclaimed asphalt pavement (RAP) aggregate, demolition concrete, cement by-pass dust (CBPD), copper slag, petroleum-contaminated soils (PCS), discarded tires, incinerator ash, and others. Recycling of such materials in construction is not practiced. Research data are also minimal into the potential use of selected materials in construction applications. This paper will present the results of several laboratory studies conducted into the use of PCS in asphalt concrete mixtures; on the use of CBPD in soil stabilization and flowable fill mixtures; on the utilization of copper slag and CBPD as cementitious materials; on the use of incinerator ash in cement mortars; and on the use of RAP aggregate in road bases and sub-bases. Laboratory data generally indicate that it is feasible to partially reuse some of these materials in construction provided that economic incentives and environmental concerns are taken into consideration.     

The influence of institutions and organizations on urban waste collection systems: an analysis of waste collection system in Accra, Ghana (1985-2000)

Urban waste collection system is a pivotal component of all waste management schemes around the world. Therefore, the efficient performance and the success of these schemes in urban pollution control rest on the ability of the collection systems to fully adapt to the prevailing cultural and social contexts within which they operate. Conceptually, institutions being the rules guiding the conduct of public service provision and routine social interactions, waste collection systems embedded in institutions can only realize their potentials if they fully evolve continuously to reflect evolving social and technical matrices underlying the cultures, organizations, institutions and social conditions they are designed to address. This paper is a product of an analysis of waste collection performance in Ghana under two different institutional and/or organizational regimes; from an initial entirely public sector dependence to a current mix of public-private sector participation drawing on actual planning data from 1985 to 2000. The analysis found that the overall performance of waste collection services in Ghana increased under the coupled system, with efficiency (in terms of total waste clearance and coverage of service provision) increasing rapidly with increased private-sector controls and levels of involvement, e.g. for solid waste, collection rate and disposal improved from 51% in 1998 to about 91% in the year 2000. However, such an increase in performance could not be sustained beyond 10 years of public-private partnerships. This analysis argues that the sustainability of improved waste collection efficiency is a function of the franchise and lease arrangements between private sector group on the one hand and public sector group (local authorities) on the other hand. The analysis therefore concludes that if such franchise and lease arrangements are not conceived out of an initial transparent process, such a provision could undermine the overall sustainability of private sector initiatives in collection services delivery in the long term, as in the case of the Accra example.     

Critical factors for waste management in office building retrofit projects in Australia

Office building retrofit is a sector being highlighted in Australia because of the mature office building market characterised by a large proportion of ageing properties. The increasing number of office building retrofit projects strengthens the need for waste management. Retrofit projects possess unique characteristics in comparison to traditional demolition and new builds such as partial operation of buildings, constrained site spaces and limited access to as-build information. Waste management activities in retrofit projects can be influenced by issues that are different from traditional construction and demolition projects. However, previous research on building retrofit projects has not provided an understanding of the critical issues affecting waste management.This research identifies the critical factors which influence the management of waste in office building retrofit projects through a literature study and a questionnaire survey to industry practitioners. Statistical analysis on a range of potential waste issues reveals the critical factors, as agreed upon by survey respondents in consideration of their different professional responsibilities and work natures. The factors are grouped into five dimensions, comprising industry culture, organisational support and incentive, existing building information, design, and project delivery process. The discussions of the dimensions indicate that the waste management factors of office building retrofit projects are further intensified compared to those for general demolition and construction because retrofit projects involve existing buildings which are partially operating with constrained work space and limited building information. Recommendations for improving waste management in office building retrofit projects are generalised such as waste planning, auditing and assessment in the planning and designing stage, collaboration and coordination of various stakeholders and different specialists, optimised building surveying and BIM technologies for waste analysis, and new design strategies for waste prevention.     

Environmental accounting for waste management: A study of local governments in Australia

Local governments in Australia, especially in large urban areas, have faced a challenge of the growing quantity of waste generated and the diminishing space for waste disposal in recent years. The central government has demonstrated the importance of developing strategies to make full environmental costs and impacts of waste disposal and material recovery accountable for waste management decision-making. However, research into this field is limited. This paper investigates environmental accounting practices in local government waste management. From a survey conducted with local government authorities in New South Wales (NSW) Australia, it is found that overall the level of direct waste flow and activity accounting is higher than the level of hidden and external environmental cost accounting, though local governments tend to identify and use more physical information associated with waste flows and activities than relevant monetary information. External environmental impacts of waste disposal are often overlooked and show the lowest level of practices. The survey results also indicate that urban local governments have taken more environmental information into account than rural local governments, but such difference is not significant between local governments of different sizes. The complexity of waste technical services and operations is confirmed to have a positive and significant effect on the level of environmental accounting for waste management across local governments surveyed.     

A system dynamics model for evaluating the alternative of type in construction and demolition waste recycling center - The case of Chongqing, China

This paper presents a system dynamics computer model to evaluate alternative type of recycling center under different policy and economy environments through comparison on the economic feasibility of recycling centers and ratio of savings to costs in C&D waste management. A case study for the City of Chongqing, China is selected. Simulated results show three key factors can contribute to the economic feasibility of recycling and the ratio of savings to costs in C&D waste management: (a) profit; (b) unit recycling cost; (c) extra revenue from location advantage (It was assumed that the mobile centers can attain extra revenue from the location advantage compared with fixed recycling centers). The sensitive analysis and comparison on ratios between public and private sector indicate that to achieve the optimum ratio of savings to costs, design of recycling centers and selection of governmental instruments are determined by the priority list: (1) low extra revenue from location advantage; (2) low profit; (3) low unit recycling cost. Meanwhile, the fluctuation of the three factors must be prior to achieve economic feasibility of corresponding recycling centers.     

Recycling — an environmentally friendly and income generating activity towards sustainable solid waste management. Case study — Dar es Salaam City, Tanzania

Traditionally solid waste management has evolved as mainly the removal of municipal wastes by hauling them out of the city boundaries and dumping them ‘there’. This is in conformity with the ‘out of sight out of mind’ philosophy. However, with the ever increasing tonnage of refuse due to the expansion of urban centers, which implies increased collection, transportation and disposal costs, recycling is currently accepted as a sustainable approach to solid waste management. This paper reports on the findings of a study, conducted in the city of Dar es Salaam between the years 1993 and 1995, on the scavenging activities and recycling trends of some selected items in Dar es Salaam. Apart from the discussions on existing solid waste generation rates (2000 tonnes/day), composition (60% being organic/or vegetable matter) and their management in Dar es Salaam, the paper also presents data obtained through a survey of Vingunguti dump site and other waste collection centers. It was established that there are currently about 600 solid waste scavengers in Dar es Salaam, approximately 109 of whom operate at Vingunguti dump site and others at 14 different collection centers. Many of them opted for scavenging due to unemployment. The study findings indicate that their average monthly income exceeded the official minimum wage (at the time of study) enabling them to support their families. This demonstrates the potential of recycling to generate gainful employment with implied lower crime rates among the unemployed. Recycling activities in the city were observed to be not only a critical source of raw materials for small-scale industries, in the absence of which they would cease to operate, but also a widely accepted environmentally friendly technology for solid waste management. Out of 294 tonnes of studied waste materials (paper, metal, plastic, glass and textiles) only 4 tonnes are recovered and recycled. The remaining 290 tonnes/day of recyclable material are left to pollute the environment or are collected and transported for final disposal and, therefore, unnecessarily contribute to the shortening of the life span of the dump site. Finally, the paper gives some recommendations for improved recycling activity so as to make it an important means of reducing the overall volume of waste materials to be transported and deposited in the dump site and at the same time provide a potential opportunity for employment for unskilled workers.     

Utilization of waste foundry sand (WFS) in concrete manufacturing

Due to ever increasing quantities of waste materials and industrial by-products, solid waste management is the prime concern in the world. Scarcity of land-filling space and because of its ever increasing cost, recycling and utilization of industrial by-products and waste materials has become an attractive proposition to disposal. There are several types of industrial by-products and waste materials. The utilization of such materials in concrete not only makes it economical, but also helps in reducing disposal concerns. One such industrial by-product is waste foundry sand (SFS). Waste foundry sand is a by-product of ferrous and nonferrous metal casting industries. Foundries successfully recycle and reuse the sand many times in a foundry. When the sand can no longer be reused in the foundry, it is removed from the foundry and is termed as waste foundry sand.Published literature has shown that WFS could be used in manufacturing Controlled Low-Strength Materials (CLSM) and concrete. This paper presents an overview of some of the research published on the use of WFS in concrete. Effect of WFS on concrete properties such as compressive strength, splitting tensile strength, modulus of elasticity, freezing-thawing resistance, and shrinkage are presented.     

废弃电池能否进入废弃电器电子产品处理目录(第二批)管理的筛选评估分析

2009年2月,国务院发布《废弃电器电子产品回收处理管理条例》,成为我国废弃电器电子产品回收处理的纲领性文件。在《废弃电器电子产品处理目录(第一批)》中,明确将电视机、电冰箱、洗衣机、房间空调器、微型计算机等5种产品纳入第一批目录。同时,为了为了能够及时、客观地与经济发展、技术进步以及电器电子产品行业的发展变化等相适应,《目录》管理委员会起草了《制订和调整废弃电器电子产品处理目录的若干规定》,明确随着经济发展变化及电子产品废弃形势调整电器电子产品处理目录的原则。废弃电池在近几年来在我国增长速度很大,将来的管理形势十分紧迫。本文在此分析我国几种废弃电池(铅酸电池、镍氢电池及锂电池)的产生量、再生处理处置情况及管理政策导向。并在目录一批筛选原则的基础上利用权重分析法,筛选评估废弃电池能否进入废弃电器电子产品处理目录(第二批)管理的可能,研究显示铅酸电池已具备进入管理目录的资质。     

Personality, individual differences, and demographic antecedents of self-reported household waste management behaviours

The present study sought to extend recent conceptual frameworks of waste management behaviours by examining personality, individual differences, and socio-demographic antecedents of self-reported waste recycling, reuse, and reduction behaviours. A total of 203 participants from a British community sample completed a questionnaire consisting of measures of their self-reported waste management behaviour, Machiavellianism, political cynicism, the Big Five personality traits, and socio-demographics. The results of structural equation modelling showed that individuals who were less Machiavellian, less politically cynical, older, and more conscientious were more likely to report positive waste management behaviours. In combination, these predictors explained 22.0% of the variance in waste management behaviours. Thus, these variables may improve the predictive validity of existing conceptual models of waste management behaviours. The results are discussed in relation to those models.     

Valuation of externalities of selected waste management alternatives: A comparative review and analysis

Accessible and transparent data on the social costs of externalities is crucial to waste management researchers, decision-makers, and managers, if waste management strategies are to be successfully analyzed and implemented. The primary objective of this study, which is based on a thorough review of existing literature and research, was to assist the abovementioned in their decision-making with reliable recent data, by mapping, gathering, analyzing, and comparing different valuation results of external costs associated with various types of pollution and disamenities related to landfilling and incineration of solid waste.The second objective was to assess the suitability and reliability of various valuation methods and techniques that were implemented in the reviewed valuation studies, as well as the transferability of valuations across sites.The paper focuses on studies conducted since 1990, because in dynamic fields such as the waste sector, externalities, and valuation, it is essential to stay current with the most recent information and valuations.We discuss the issues and the limits of the valuation techniques and analyze the estimates of all the studies, presenting the results in the form of intervals and averages of damage costs. In spite of the inconsistencies evident in the variability in the results we reviewed, the outcome of this first comprehensive critical analysis is significant and the valuations obtained in this study provide estimates of orders of magnitude of external costs that can be used by decision makers in the waste sector to address important policy questions associated with social welfare.     

Evaluation of environmental management resources (ISO 14001) at civil engineering construction worksites: a case study of the community of Madrid

In recent years, significant advances have been made in business organization and management. The growing demands of clients as well as the globalization of world markets are among the many factors that have led to the establishment of systems of quality control and environmental management as a competitive strategy for businesses. When compared to other professional sectors, the construction sector has been slower to respond to environmental problems and to adopt Environmental Management Systems (EMS). In the world today the ISO 14001 standard is currently the main frame of reference used by construction companies to implement this type of management system. This article presents the results of a general study regarding the evaluation of the application of the ISO 14001 standard at civil engineering construction worksites in the Community of Madrid (Spain), specifically pertaining to requirement 4.4.1, Resources, roles, responsibilities, and authority. According to requirement 4.4.1, company executives should appoint people responsible for implementing the EMS and also specify their responsibilities and functions. The personnel designated for supervising environmental work should also have sufficient authority to establish and maintain the EMS. The results obtained were the following: - EMS supervisors did not generally possess adequate training and solid experience in construction work and in the environment. Furthermore, supervisors were usually forced to combine their environmental work with other tasks, which made their job even more difficult. - Generally speaking, supervisors were not given sufficient authority and autonomy because productivity at the construction site had priority over environmental management. This was due to the fact that the company management did not have a respectful attitude toward the environment, nor was the management actively involved in the establishment of the EMS. - Insufficient resources were allocated to the Environmental Management Unit. As a result, the application of EMSs in construction projects often appeared to be more of a formality, which was merely a way of maintaining the certification of the Environmental Management System. It was more a means of meeting the requirements for submitting a tender to contracting organisms rather than an indicator of any real commitment to improving the environmental performance of construction companies.     

Sustainable management of demolition waste—an integrated model for the evaluation of environmental, economic and social aspects

A model is presented for evaluating waste management systems for their contribution to a sustainable development, including environmental, economic and social aspects. The model was tested in a case-study, where groups of long-term unemployed people were offered both education on environmental issues and practical work with the recovery and recycling of building and demolition waste as a form of vocational development. Application of the suggested model revealed the overall effects on sustainability of different methods of waste management. In addition, negative aspects of the systems analysed were identified, which led to discussions about possible improved practices within the waste management systems. Two of the waste management systems investigated (the recycling of steel and re-use of sanitary porcelain) showed a potential contribution to sustainable development in all of the aspects studied. Preparing bricks for re-use showed the largest potential for eco-efficiency, but had negative effects on sustainability from the social perspective of health and the working environment. The possibility of further use of the model and the remaining obstacles to such analyses are discussed. One observation is that the data collection needed to perform this kind of sustainability analysis is resource-demanding, and that it would therefore be better to identify a smaller number of key indicators.     

Critical analysis of the waste management performance of two uranium production units in Brazil--part II: Caetite production center

This paper discusses the environmental waste management of the Heap-Leach Uranium Production Facility of Caetité located in a semi-arid region in Brazil. A comparison is made with the first uranium production site of the country located in Poços de Caldas. It is demonstrated that differences in the operational process along with different environmental conditions can lead to different impacts. In the present case groundwater is the potential most sensitive environmental medium despite the well-established consensus in the literature that radon and aerosol emissions may turn-out to be the most relevant environmental aspects of an installation located at this type of region. Most of the ²²⁶Ra content in the ore remains in the leached ore that is deposited with the waste rock. A lack in appropriate prediction of the hydrological balance has been causing unanticipated emissions of liquid effluents into the environment. Chemical treatment of this effluent may be needed. Contamination of groundwater in the short term by the waste ponds is not to be expected but it can be a relevant issue in the long term. As a consequence, careful closure schemes will need to be put in place. Finally, the overall costs with remediation in the Caetité production center are lower than those observed at the Poços de Caldas mining site.