Showing papers in "Resources Conservation and Recycling in 2008"

Overview of electronic waste (e-waste) management practices and legislations, and their poor applications in the developing countries

Abstract: The developing countries are facing huge challenges in the management of electronic waste (e-waste) which are either internally generated or imported illegally as ‘used’ goods in an attempt to bridge the so-called ‘digital divide’. E-waste contains hazardous constituents that may negatively impact the environment and affect human health if not properly managed. In these countries, because of lack of adequate infrastructure to manage wastes safely, these wastes are buried, burnt in the open air or dumped into surface water bodies. Crude ‘backyard’ recycling practices, which are not efficient and are highly polluting are also used in material recovery activities. Most developed countries have in place legislation mandating electronic manufacturers and importers to take-back used electronic products at their end-of-life (EoL) based on the principle of extended producer responsibility (EPR). In this paper, we review the concept of EPR, and discuss selected frameworks. The aim has been to find a mid point for the implementation of even an ‘abridged’ form of EPR in the developing countries. Implementation of EPR in the developing countries has become necessary in the light of the present high level of trans-boundary movement of e-waste into the developing countries and the lack of basic or state-of-the-art recycling and waste disposal facilities. Change in attitude by governments, appropriate legislation dealing specifically with e-waste, control of electronic waste dumping, implementation of EPR and transfer of technology on sound recycling of e-waste are the key issues in effective management of e-waste in developing countries.

Utilization of copper slag in cement and concrete

Abstract: Copper slag is a by-product obtained during matte smelting and refining of copper. The common management options for copper slag are recycling, recovering of metal, production of value added products such as abrasive tools, roofing granules, cutting tools, abrasive, tiles, glass, road-base construction, railroad ballast, asphalt pavements. Despite increasing rate of reusing copper slag, the huge amount of its annual production is disposed in dumps or stockpiles to date. One of the greatest potential applications for reusing copper slag is in cement and concrete production. Many researchers have investigated the use of copper slag in the production of cement, mortar and concrete as raw materials for clinker, cement replacement, coarse and fine aggregates. The use of copper slag in cement and concrete provides potential environmental as well as economic benefits for all related industries, particularly in areas where a considerable amount of copper slag is produced. This paper reviews the characteristics of copper slag and its effects on the engineering properties of cement, mortars and concrete.

Exploring e-waste management systems in the United States

Abstract: Quantities of end-of-life electronics (or e-waste) around the world keep growing. More than 1.36 million metric tons of e-waste were discarded, mainly in landfills, in the U.S. in 2005, and e-waste is projected to grow in the next few years. This paper explores issues relating to planning future e-waste regulation and management systems in the U.S. It begins by reviewing the existing U.S. recycling systems in the U.S. to establish the importance of developing public responses. Other countries and regions around the world have already legislated and implemented electronic takeback and recycling systems. To establish the context of existing experience, e-waste management systems in the European Union, Japan, South Korea and Taiwan are explored. The paper then discusses what specific conditions are expected to influence the acceptability and implementation in the U.S. A key consideration is the cultural imperative in the U.S. for market-driven solutions that enable competition. Given this context, a solution is proposed that is designed to ensure a proper end-of-life option while at the same time establishing a competitive market for reuse and recycling services. The solution, termed e-Market for Returned Deposit , begins with a deposit paid by consumers to sellers at the time of purchase, electronically registered and tracked via a radio-frequency identification device (RFID) placed on the product. At end-of-life, consumers consult an Internet-enabled market in which firms compete to receive the deposit by offering consumers variable degrees of return on the deposit. After collection of the computer by the selected firm, the cyberinfrastructure utilizes the RFID to transfer the deposit to the winning firm when recycled. If the firm chooses to refurbish or resell the computer in lieu of recycling, the transfer is deferred until true end-of-life processing. Finally the paper discusses the domestic and international consequences of the implementation of the proposed design.

Recycling and reuse of waste concrete in China: Part I. Material behaviour of recycled aggregate concrete

Abstract: From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse waste concrete as recycled concrete aggregate (RCA) for new concrete, often referred to as recycled aggregate concrete (RAC). In the recent years, intensive researches on this topic have been carried out in China and several successful applications of RAC in practical engineering were also performed. This paper provides an introduction of the background information for the recycling of waste concrete in China and a critical review of the related studies and achievements on the material behaviour of RAC. The following aspects are mainly focused on: the production of RCA, the mechanical behaviour of RAC (both strength and deformation characteristics) and the durability aspects of RAC. Furthermore, a brief introduction to the provisions for RCA and material behaviour of RAC specified in the first standard for RAC in China—Technical Code for Application of Recycled Aggregate Concrete (DG/TJ07-008), issued in 2007, was also presented.

Energy and environmental indicators related to construction of office buildings

Abstract: Buildings’ construction has a major determining role on the environment through consumption of land and raw materials and generation of waste. It is also a significant user of non-renewable energy and an emitter of greenhouse gases and other gaseous wastes. As environmental issues continue to become increasingly significant, buildings become more energy efficient and the energy needs for their operation decreases. Thus, the energy required for construction and consequently, for the material production, is getting of greater importance. The present paper investigates the role of different construction materials and quantifies them in terms of the embodied energy and the equivalent emissions of CO 2 and SO 2 in contemporary office buildings. It also assesses the importance of the embodied energy of the building's structure as compared to the operational energy of the building. It was shown that the embodied energy of the structure's building materials (concrete and reinforcement steel) represents the largest component in the building's total embodied energy of the examined buildings, varing from 66.73% to 59.57%, while the embodied energy of the building envelope's materials represents a lower but significant proportion of the building's total embodied energy. When the construction elements are examined, the slabs have the higher contribution at the embodied energy of the studied buildings and from the envelope elements, the external wall is contributing the maximum in the overall embodied energy of the building. The embodied energy correspondence varies between 12.55 and 18.50% of the energy needed for the operation of an office building over a 50 years life.

Does privatization of solid waste and water services reduce costs? A review of empirical studies

Abstract: Cost reduction was the key benefit claimed by privatization. We conduct a review of all published econometric studies of water and waste production since 1970. Little support is found for a link between privatization and cost savings. Cost savings are not found in water delivery and are not systematic in waste. Reviewed studies build from public choice, property rights, transaction costs and industrial organization theories. We conclude public choice theory is too focused on competition, which is typically not present in quasi-markets. Property rights theory gives attention to ownership and service quality, but absent competition, ownership makes little difference on costs borne by municipalities. Transaction costs argue privatization is best when contracts are complete—a rare situation in public service markets. We find the industrial organization approach most useful in explaining results because it directly addresses incentives, sector structure and regulatory framework. Overall, the empirical results show the importance of market structure, industrial organization of the service sector, and government management, oversight and regulation. Because there is no systematic optimal choice between public and private delivery, managers should approach the issue in a pragmatic way.

Waste generation, waste disposal and policy effectiveness Evidence on decoupling from the European Union

Abstract: Waste generation and waste disposal are issues that are becoming increasingly prominent in the environmental arena both from a policy perspective and in the context of delinking analysis Waste generation is still increasing proportionally with income, and economic and environmental costs associated to landfilling are also increasing Thus, the need of accelerating the eventual delinking process by the introduction of policies at all stages of waste production and disposal This paper provides a comprehensive analysis of waste generation, incineration, recycling and landfill dynamics based on panel data for the EU25, to assess the effects of different drivers (economic, structural, policies) and the eventual heterogeneity on such evidence between western and eastern EU countries We show that for waste generation there is still no absolute delinking trend, although elasticity to income drivers appears lower than in the past Landfill and other policy effects do not seem to provide backward incentives for waste prevention Regarding landfill and incineration, the two trends, as expected, are respectively decreasing and increasing, with policy effects providing a strong driver It demonstrates the effectiveness of policy even in this early stage of policy implementation This is essential for an ex post evaluation of existing landfill and incineration directives Nevertheless, it signals the risk of widening gaps between early adopters and countries which postpone ratification and implementation It is also worth noting that EU15 and EU10 groups of countries show some different waste trends and driving forces of waste generation and landfill diversion hen analysed separately We may conclude that although complete delinking is far from being achieved – especially for waste generation, there are some positive signals, and signs of a quite significant role of the EU waste policies implemented in the late 1990s and early 2000s

On the modulus of elasticity and strain capacity of Self-Compacting Concrete incorporating rubber aggregates

Abstract: Cement-based materials suffer from low tensile strength and poor strain capacity. They are brittle and highly sensitive to cracking, notably to shrinkage cracking, which is particularly detrimental for large surface areas. This paper focuses on the properties of a Self-Compacting Concrete (SCC) incorporating rubber aggregates, obtained by grinding end-of-life tyres, as a partial replacement for natural aggregates. Results show that the new cementitious material goes against some governing principles of mechanical behaviour of ordinary cement-based concrete. In particular, the modulus of elasticity of rubberized SCC is reduced and its variation with rubber aggregate content does not obey the conventional empirical relationship of modulus of elasticity with compressive strength. The strain capacity of SCC was quantified through flexural bending tests, which demonstrated that strain capacity increased when rubber aggregates were incorporated in concrete. This response is interpreted as a result of the ability of rubber aggregates to reduce the stress singularity at the first crack tips running into the rubber/cement–matrix interface, a mechanism slowing the cracking kinetics and delaying macrocrack localization. In such conditions, rubberized SCC is expected to be suitable when resistance to the cracking due to imposed deformation is a priority. This type of composite with low modulus of elasticity is also suitable for Controlled Modulus Columns (CMC) foundations, the ultimate solution for improving very soft soils subjected to settlement or stability problems caused by insufficient bearing capacity. Incidentally, the use of rubber aggregates in SCC provides an opportunity to recycle non-reusable end-of-life tyres.

Spent catalyst waste management: A review: Part I—Developments in hydroprocessing catalyst waste reduction and use

Abstract: Solid catalysts containing metals, metal oxides or sulfides, which play a key role in the refining of petroleum to clean fuels and many other valuable products, become solid wastes after use. In many refineries, the spent catalysts discarded from hydroprocessing units form a major part of these solid wastes. Disposal of spent hydroprocessing catalysts requires compliance with stringent environmental regulations because of their hazardous nature and toxic chemicals content. Various options such as minimizing spent catalyst waste generation by regeneration and reuse, metals recovery, utilization to produce useful materials and treatment for safe disposal, could be considered to deal with the spent catalyst environmental problem. In this paper, information available in the literature on spent hydroprocessing catalyst waste reduction at source by using improved more active and more stable catalysts, regeneration, rejuvenation and reuse of deactivated catalysts in many cycles, and reusing in other processes are reviewed in detail with focus on recent developments. Available methods for recycling of spent hydroprocessing catalysts by using them as raw materials for the preparation of active new catalysts and many other valuable products are also reviewed.

Spent hydroprocessing catalyst management: A review: Part II. Advances in metal recovery and safe disposal methods

Abstract: Petroleum refineries must pay attention to spent hydroprocessing catalysts particularly since they are hazardous toxic wastes. This review focuses on the progress in metal reclamation and disposal methods used for dealing with the environmental problem of spent hydroprocessing catalysts. Studies have been conducted with the aim either to increase the efficiency of metals recovery using established methods or to develop novel methods. Leaching studies used inorganic agents such as solutions of strong acids and bases, ammonium containing compounds and water soluble organic acids. The roasting of spent catalysts with sodium and/or potassium salts significantly enhanced solubility of some metals in water from where they could be recovered, in a pure form, either by selective precipitation or extraction using various extracting agents. The interests in bioleaching and electrochemical dissolution of metals were also reviewed. Commercial processes, involve either leaching out metals or roasting to make metals soluble in water. Markets and price trends for the metals in spent hydroprocessing catalysts are also discussed. To ensure the environmental acceptance, spent catalysts may require some pretreatments if disposal in landfills, is chosen as the last option. The aim is to make metals non-leachable by immobilizing them using thermal treatments with encapsulating agents. Consequently, the leachability of the metals is minimized. A number of methods and various agents have been evaluated for these purposes.

Public participation and recycling performance in England: A comparison of tools for behaviour change

Abstract: Improving the quality and capture of materials collected for recycling is at the top of the waste agenda for many English local authorities. In recent years, the focus has shifted away from general awareness raising techniques in favour of methods that can bring about behaviour change. This paper reports on three projects each using a different behaviour change based approach, which all aimed to increase participation in the recycling collection scheme and to reduce inclusion of non-targeted materials (“contamination”). The three projects—one doorstepping-based, one incentives-based and one delivering personalised feedback to residents were carried out in Portsmouth between 2005 and 2006 during a period where there were no major changes to the collection infrastructure. The findings show that personalised incentives and feedback were highly effective at reducing contamination. Both methods resulted in a halving of the number of households setting out contaminants on collection day. The feedback approach was considerably more cost-effective than the other two approaches, costing ∼£0.50 per household to implement the campaign and averaging ∼£3.00 for every household which subsequently displayed behaviour change. There was little improvement in the quality of collected materials attributed to doorstepping alone. None of the projects resulted in significant changes in recycling scheme participation; however, this may be because participation was initially high. These findings suggest that behaviour change is most effectively brought about using simple, low-cost methods to engage with residents at the point of service delivery, i.e. by the collection crews whilst emptying bins. The challenge now is to integrate this into service delivery as standard.

Economic comparison of concrete recycling : a case study approach

Abstract: Recycling of construction material helps saving the limited landfill space. Among various types of materials, concrete waste accounts for about 50% of the total waste generation. The current practice for dumping construction materials to landfills generates a significant quantity of waste from construction sites. Recycling concrete waste as recycled aggregate is one of the methods to reduce the concrete waste. Therefore, this paper investigates the economical considerations in recycling concrete waste. A comparative study on costs and benefits between the current practice and the concrete recycling method is examined. The study shows that it has a negative net benefit for the current practice while a positive net benefit for the concrete recycling method. Therefore, recycling concrete as aggregate for new concrete production can provide a cost-effective method for the construction industry and help saving the environment.

Composts from distillery wastes as peat substitutes for transplant production

Abstract: The use of composts from distillery wastes as alternative growing media ingredients for transplant production instead of peat, whose harvesting constitutes a severe environmental damage, was studied. Two composts were prepared with exhausted grape marc and cattle manure (C1), and with exhausted grape marc and poultry manure (C2). Four vegetable species, lettuce ( Lactuca sativa ), chard ( Beta vulgaris ), broccoli ( Brassica oleracea ) and coriander ( Coriandrum sativum ) were grown. Nine substrates were compared: limed white peat (control); compost C1; compost C2; and six mixtures containing 25%, 50% and 75% by volume of each compost with the corresponding peat as diluent. The germination and the effects on the transplant morphological and nutritional aspects of the different mixtures peat/compost considered were studied. All media elaborated showed adequate physical, physico-chemical and chemical properties compared to peat for their use as growing media in horticulture, being these two composts suitable ingredients for the partial substitution of peat, in quantities of 25–50% by volume, without causing any loss in the yield and in the results obtained for the nutritional status when compared to those obtained using the control.

Life cycle assessment on using recycled materials for rehabilitating asphalt pavements

Abstract: This research performed life cycle inventory using proposed recycled material formulas and service records and incorporating the database provided by Eco-indicator 99 in order to study the eco-burden presented by using recycled materials to rehabilitate asphalt pavements. Three recycled materials (recycled hot mix asphalt, asphalt rubber, and Glassphalt) and the traditional hot-mixed asphalt are compared. Assuming that the thickness of the asphalt is 5 cm and the service life is 6 years, the eco-burden presented by the traditional hot-mixed asphalt is 3.45 kPt. per lane-kilometer. Using recycled hot mixed asphalt can reduce the eco-burden by 23% under the same conditions. Using asphalt rubber increases the eco-burden by 16%, while the eco-burden remains essentially the same (reduced by less than 1%) using Glassphalt. Taking into account the difference in service life between different materials, this research also uses a 40-year time span to evaluate the eco-burden for each material. The results show that the traditional hot mixed asphalt has an eco-burden of 23.03 kPt. for that time span. Both recycled hot mixed asphalt and asphalt rubber can reduce the eco-burden by 23% in the same period. On the contrary, Glassphalt increases the eco-burden by 19%. This research also identified the sources of the eco-burden for these asphalts. The results show that a large percentage of the eco-burden comes from two sources, the asphalt binder used (39–48%) and the heat sources required to process these paving materials (42–50%). This suggests that the most effective way to lower the eco-burden may be to reduce the heat requirement during the manufacturing process.

Environmental performance of wastewater treatment plants for small populations

Abstract: Life cycle assessment (LCA) is an environmental tool which allows the calculation of all the environmental loads related to a process/product/service. In the present work, LCA was applied to analyze the environmental impact of different technologies for wastewater treatment in small populations. In this study, 13 wastewater treatment plants (WWTPs) of less than 20,000 population equivalent (p.e.) located in Galicia (NW Spain) were inventoried. The results of the evaluation of the environmental impact are expressed in terms of diverse impact categories. Normalization identified eutrophication, mainly as P-PO43−, N-NH4+ and organic load as chemical oxygen demand (COD) in the treated effluent, and terrestrial ecotoxicity, due to the heavy metals content in the sludge, as the most significant categories for all WWTPs. Electricity use plays an important role in five of seven impact categories and presents the highest importance in four of them. When comparing technologies, secondary treatment technologies such as biodenipho and aerobic–anoxic treatment resulted in a lesser environmental impact than extended aeration. The operation of the plants has large contribution on the impact, especially for those that make use of extended aeration.

Development of a recycled polymer modified binder for use in stone mastic asphalt

Abstract: The number of commercial vehicles using Irish roads has increased considerably in recent years, leading to higher demands being placed on pavement materials and increased use of polymer modified bitumens. This has also coincided with significant changes in Governmental policy which has produced large increases in Irish recycling rates. Improved recycling levels are set to provide Ireland with a new challenge: to find potential uses for the large quantities of recycled polymer that are becoming available. Towards this end, the potential of developing a recycled polymer modified binder was investigated. The polymers most commonly recycled in Ireland were identified and sourced from industry. Fundamental bitumen tests were conducted to assess the effect of the recycled polymer and a mixing methodology developed. It was found that the addition of 4% recycled HDPE into a pen grade binder produced the most promising results, and the mixing process was then optimised with respect to mixing parameters and binder additives. A developmental recycled binder was produced and compared in performance tests to binders currently used in road construction practice. Results obtained from wheel track and fatigue tests show that although the binder does not deliver equivalent performance levels to a proprietary polymer modified binder, it does out-perform traditional binders used in stone mastic asphalt. Recommendations are offered on the further development of the recycled polymer modified binder to achieve the standards currently required.

An analysis of some environmental consequences of European electrical and electronic waste regulation

Abstract: In recent years, new European Directives have been issued to ensure that Waste Electrical and Electronic Equipment (WEEE) is treated in as environmentally friendly a way as possible. These new European laws call for the creation of new logistics networks to collect all such waste. The purpose of this paper is to show that, under certain circumstances, the environmental impact of these networks could be even higher than the impact of non-collection. Different appliances were analysed (washing machines, refrigerators, TV sets and personal computers) in order to test this hypothesis. The methodology of Life Cycle Assessment (LCA) was applied, highlighting especially the final phase of product life and calculating the threshold beyond which collection is harmful for each type of equipment. The results demonstrate that, depending on the distance travelled to pick up the domestic appliances, recycling is not as environmental friendly as expected, especially when it comes to the impact of fossil fuels or respiratory inorganics (winter smog). This work can be a useful tool for manufacturers (now forced to take back all the equipment after use for subsequent treatment) when designing their new recycling networks from an environmental perspective.

Life cycle assessment of waste paper management: The importance of technology data and system boundaries in assessing recycling and incineration

Abstract: The significance of technical data, as well as the significance of system boundary choices, when modelling the environmental impact from recycling and incineration of waste paper has been studied by a life cycle assessment focusing on global warming potentials. The consequence of choosing a specific set of data for the reprocessing technology, the virgin paper manufacturing technology and the incineration technology, as well as the importance of the recycling rate was studied. Furthermore, the system was expanded to include forestry and to include fossil fuel energy substitution from saved biomass, in order to study the importance of the system boundary choices. For recycling, the choice of virgin paper manufacturing data is most important, but the results show that also the impacts from the reprocessing technologies fluctuate greatly. For the overall results the choice of the technology data is of importance when comparing recycling including virgin paper substitution with incineration including energy substitution. Combining an environmentally high or low performing recycling technology with an environmentally high or low performing incineration technology can give quite different results. The modelling showed that recycling of paper, from a life cycle point of view, is environmentally equal or better than incineration with energy recovery only when the recycling technology is at a high environmental performance level. However, the modelling also showed that expanding the system to include substitution of fossil fuel energy by production of energy from the saved biomass associated with recycling will give a completely different result. In this case recycling is always more beneficial than incineration, thus increased recycling is desirable. Expanding the system to include forestry was shown to have a minor effect on the results. As assessments are often performed with a set choice of data and a set recycling rate, it is questionable how useful the results from this kind of LCA are for a policy maker. The high significance of the system boundary choices stresses the importance of scientific discussion on how to best address system analysis of recycling, for paper and other recyclable materials.

Assessment of factors influencing the performance of solid waste recycling programs

Abstract: Municipal solid waste management (SWM) problems present a serious challenge to local government authorities (LGAs) in developing countries. The effective way to reduce this tremendous issue is to integreate waste recycling systems into existing and future SWM. Understanding factors influencing recycling performance is the key to achieving sustainable waste management. The purpose of this study is to investigate the factors influencing the performance of SWM relating to solid waste recycling covering a total of 120 solid waste recycling programs located in different urban areas of Thailand. The indicators involving efficiency, effectiveness and service ratio were used for the assessment of recycling performance using statistical analysis methods. Influencing factors encompassing technical, economic and financial, and institutional aspects were identified for three types of recycling programs (school garbage bank, community garbage bank, and composting facility). The results suggest that common significant factors are perception of administrator awareness of SWM problems, and source separation. In terms of school garbage banks, the provision of monetary incentive including interest and compensatory goods for recycling members, transportation cost, and low investment costs significantly affect the performance. Provision of loans, managing the program as a cooperative organization, and provision of door-to-door service correlate with better performance by community garbage banks. For composting facilities, provision of free organic waste bins and cooperation with NGOs correlate with a higher rate of waste diversion. The findings also propose implications for enhancing the performance of recycling systems through a number of measures including provision of monetary incentive, tax incentives, subsidizations, information dissemination, awareness campaigns, training, technical assistance, staff exchanges, and networking with voluntary organizations—which should be formulated with respect to building capacity of development partners, responding to poor recycling performance, and focusing on significant influencing factors.

Application of analytical hierarchy process to analyze stakeholders preferences for municipal solid waste management plans, Boston, USA.

Abstract: This paper presents analytical hierarchical process (AHP) in combination with life cycle assessment (LCA) as a decision support tool for municipal solid waste (MSW) management. A proposed set of treatment plans and an array of impacts create a complex decision environment for MSW management in the city of Boston. AHP is utilized to incorporate the relative importance of the different impact categories and treatment plans into the decision scheme regarding stakeholder group's preferences. The use of biogasification and refuse derived fuel (RDF) technologies into different management plans is presented as an alternative to the actual management of household solid waste. The results of the AHP application show that between the impact categories presented, green house gas emissions and landfill capacity constrains are ranked higher rather than the cost associated to the operation of the plan and health damage associated to the treatment plans presented among the stakeholder groups. In a broader context, the use of a hierarchical approach on AHP to structure the decision problem allows the development of four different scenarios according to the contribution of each stakeholder group to the decision scheme. In this analysis, the use of biogasification was considered as the most suitable plan to follow.

Reuse of iron ore mineral wastes in civil engineering constructions: A case study

Abstract: To make mining activities more eco-friendly, it is important to conduct mining operations in a manner that is more environmentally friendly, economically feasible and socially acceptable. The volume of solid waste generated, including tailings from mineral processing activities, is one of the main pollution concerns in the mining industry. In the tiny state of Goa (India), it is becoming increasingly difficult to find space for dumping these huge volumes. And therefore ways of utilizing mine waste need to be found. This paper examines the suitability of these wastes for use in construction. Studies by others were reviewed where it was found that these wastes contain acid producing mineral phases and high concentrations of heavy metals. The presence of such concentrations can jeopardize the environment, if management of these wastes is not addressed with due consideration and care. Particle size classification on these wastes suggests that mine wastes contain coarse-grained rock, sand, silt and clays. A number of tests were then conducted on the aggregate part of mine wastes and the physico-mechanical properties were obtained. According to the results obtained the mean values of uniaxial compressive strength (UCS) of concrete cubes after 28 days of curing was found to be of the order of 21.93 and 19.91 MPa with mine aggregate and granite aggregate, respectively. Through toxicity leaching procedure tests the study also confirmed that the hydraulic binder arrests metal mobility from these wastes. This paper does not discuss the economic aspects as that was beyond the scope of the research. However, to some extent socio-economic perspective of mine waste utilization has been presented and discussed.

Application of hydrothermal reaction in resource recovery of organic wastes

Abstract: The recovery of waste substances is not only important for prevention of environmental issues, but also for rational utilization of natural resources. Hydrothermal reaction is a prominent method for the treatment of organic wastes and has been attracting worldwide attention. During the process, various reactions such as oxidation, hydrolysis, dehydration and thermal decomposition can be carried out energetically so that the reaction can be successfully used for oxidizing organic wastes to CO 2 and other innocuous end products, as well as for conversion of organic wastes to fuels or useful materials, such as biocrude, hydrogen, glucose, lactic acid, acetic acid, amino acids, etc. This article presents the concepts of the reaction, and reviews its application in organic waste recycling.

Mercury flow via coal and coal utilization by-products: A global perspective

Abstract: Mercury (Hg) has been known to society and used since ancient times. The metal has drawn considerable attention and concern due to its toxicity, persistence, bioaccumulation and long range transport in the atmosphere after emission from coal-fired utilities as well various other high temperature processes. Coal is an important fuel for the production of heat and electricity and in recent years annual hard coal production has approached a level of around 5000 million metric tonnes (Mt, t = 1000 kg). Global Hg flows via coal and coal utilization by-products (CUBs) are presented in this paper, which are important in light of the regulations to limit the global emissions of Hg and its cycling as well as its circulation via coal and the CUBs. There are no detailed statistics on the global production and consumption of coal fly ash (FA) and in this study, we have estimated the total global FA production for the year 2003 based on ash content in coals and typical flue gas control technology for pulverized coal combustion. The mode of occurrence and concentration of Hg in coal and coal FA for different countries have been evaluated and presented in this study. The total Hg amount in coals processed worldwide was found to be 1534 t in 2003 based on a global average concentration of 0.3 mg/kg in coal. In addition, “hidden” flows of Hg through export and import of coal assessed during this study, add up to about 149 t. In this study, the economic uses of the FA in different sectors such as cement industry, agriculture, land reclamation, filers for asphalt, plastic and many others have been discussed in details. However, there is not much information on uses of coal FA in the developing countries. In the final part of the paper, a short survey has been focused on a few coal producing countries including Australia, China, EU-states, India, Japan, Korea, Russia, South Africa and South American countries, addressing the status of coal and coal FA use and the fate of the Hg that is mobilized.

Feasibility of recycling pulp and paper mill sludge in the paper and board industries

Abstract: Pulp and paper mills typically generate significant quantities of non-hazardous solid waste which require management as a waste material or as a by-product. Most of these solids are removed after primary mechanical treatment, resulting in a sludge that contains large quantities of fibers, papermaking fillers, or both. Although this primary sludge is commonly landfilled, it could be recycled into production on-site, reused in other pulp and paper mills, or used in other products. In an effort to explore these possibilities, the fiber content, fiber quality, and key physical and chemical properties (humidity, ash content, abrasiveness, drainability, and O2 uptake) of 20 different primary sludges sampled in European mills are reviewed in this paper. Although sludge characteristics are highly variable across pulp and paper mill processes, sludges can be considered to fall into two main types: high-ash sludge (>30% dry weight) and low-ash sludge (<30% dry weight). Results of paper tests (caliper, breaking length, tear index, elongation, bursting strength, stiffness, opacity, whiteness, and porosity) and board tests (ring crush test, Concora medium test, corrugated crush test) suggest that at least 12 of the sludges studied could be reused in the paper and board industry. The results make it possible to differentiate three primary sludge grades: the first needs little cleaning and has appropriate strength properties to be a component of printing and writing papers, tissues, and wrapping papers; the second requires cleaning, bleaching, or both and has appropriate strength properties for applications that do not require high brightness, such as corrugated board, boxboard, and some tissue grades; the third requires cleaning and has limited strength properties, but could be used in some mills that operate using closed water cycles because the final product can tolerate a certain degree of dirt and contamination, as in some packaging and construction-paper grades. Primary sludges share several features in common with recycled paper, and therefore these two materials could be managed together.

Surplus retail food redistribution: An analysis of a third sector model

Abstract: This paper analyses food donation by large retailers to the British charity FareShare and its franchises for redistribution to charities, examining how far the aims of waste minimisation and food poverty relief are achieved. The research emphasises the logistical arrangements for retail food waste reduction. FareShare's tripartite model, in which it brokers between retailers and charities, is efficient and effective. However, our research highlights frictions within the model that may vitiate its wider application: the hierarchy of donor, redistributive agency and client limits the clients’ ability to control food flows; individual franchises’ success depends on relationships with store managers; amongst retailers, tensions exist between profit maximisation, waste minimisation and brand control. Surplus food needs to be donated early in the supply chain to maximise utility for recipients; this may conflict with logistical and property arrangements to control brands and delay ownership of food items. Possibilities for improving and extending the service delivery model are discussed, as are current limitations. For example, the logistics of redistributing perishable items limit the possibilities for extending the model to smaller retailers with more sporadic surpluses.

Current results and future perspectives for Japanese recycling of home electrical appliances

Abstract: The Japanese system of recycling home electrical appliances has several unique aspects, including (1) a limited number of target appliances, (2) a recycling fee system that requires consumers to pay a recycling fee at the time of disposal, and (3) a direct recycling obligation for manufacturers, who have a physical, rather than a financial, responsibility for their end-of-life products. We studied data from 2001 to 2007 and found that the amount of four specified home electrical appliances and their materials that was recycled increased from about 319,249 tonnes in 2001 to about 447,262 tonnes—or 3.5 kg per inhabitant—in 2006. Recycling yield and development of recycling technologies have also improved. New recycling technologies have enabled a higher rate of material recycling of plastics (i.e., a closed-loop recycling). Improved eco-design, such as design for easier disassembly, has been promoted, and the higher quality of discarded appliances has enhanced the reuse market. Hazardous substances and fluorocarbons are being well managed. Problems with the recycling system include inelastic recycling fees, illegal dumping, illegal transfer by retailers, and the limited number of target appliances. Recycling fees could be reduced; this move might reduce the incidence of illegal dumping, as would engage stakeholders in collaborative efforts against illegal dumping. Illegal transfers could be reduced by improved traceability for retailers. Products such as liquid crystal displays, plasma display panels and clothes dryers have become increasingly common and should be also be targeted for recycling.

Utilization of spent foundry sand in controlled low-strength materials and concrete

Abstract: With ever increasing quantities of industrial by-products and waste materials, solid waste management has become the principal environmental concerns in the world. Scarcity of land-filling space and due to its ever increasing cost, utilization/recycling of by-products/waste has become an attractive alternative to disposal. Several types of by-products and waste materials are generated. Each of these waste products has specific effects on the properties of cement-based materials (CLSM and Concrete). The utilization of such materials in concrete/CLSM not only makes it economical, but also do help in reducing disposal problems. Reuse of bulk wastes is considered the best environmental alternative for solving the problem of disposal. One of such industrial by-products is Spent Foundry Sand (SFS). Spent foundry sand is a by-product of ferrous and non-ferrous 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 spent foundry sand. Published literature has shown that SFS could be possibly 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 SFS in controlled low-strength materials and concrete. Effect of SFS on CLSM characteristics like plastic properties, compressive strength, permeability, and leachate analysis, and concrete properties such as compressive strength, splitting tensile strength, modulus of elasticity, freezing–thawing resistance, and shrinkage are presented.

Household solid waste characterization by family socioeconomic profile as unit of analysis

Abstract: In this paper the behavior of household solid waste generation is analyzed, using as a unit of analysis the garbage bags produced by a family during a week. For this analysis the category of family typology is used where three different family types are included: nuclear, extended and mono-parental. The objective of this research was to know the composition and quantity of solid waste generated by family typology. For this study the waste produced by 125 families during eight days was analyzed. The total number of households included in the study was 125, 67 of them were nuclear families, 45 were extended and 13 were mono-parental families. A total of 682 garbage bags were evaluated. Using the results it was possible to determine the composition and quantity of solid waste generated by family typology and by socioeconomic stratum. The results showed that the per capita and the average family waste generation varies according to the family typology and to the socioeconomic stratum where the family belongs. Per capita daily waste generation of the nuclear family was 1.10 kg, the extended family produced 0.782 kg and the mono-parental family produced 1.35 kg. In contrast waste composition did not show any difference, except for some of the categories such as garden waste, newspaper, textiles and disposable diapers, these wastes explain the lifestyles of the generators.

Mechanical behaviour and environmental impacts of a test road built with marine dredged sediments

Abstract: A full scale test road was built with marine dredged sediments at the Dunkirk harbour, in the north of France. The first objective of this work was to evaluate the compatibility of this material with current practice used to build roads with standard materials. In the second time, the impacts of time on the mechanical behaviour and the concentration of contaminants in the leachates, such as trace metals and chlorides of the used material, were evaluated. In regards of the obtained results, the mechanical behaviour seems compatible with the technical properties targeted in the design stage. In terms of the environmental impacts, the concentrations of organic and inorganic pollutants were measured after leaching tests. The main pollutants and their respective concentration in leachates, except for chloride, were below the used threshold. After 1-year follow-up, the concentration of chloride does not seem to decrease. The experience gained shows, from a technical as an economical point of view, that the proposed methodology could constitute an interesting issue for dredged sediments management.

Stability evaluation of compost by respiration techniques in a rotary drum composter

Abstract: Stability of compost using respiration techniques is evaluated for four C/N ratio waste combinations (C/N 16, C/N 22, C/N 30 and C/N 38) of grass cutting, mix vegetable waste, cattle manure, food waste and sawdust in a rotary drum composter. CO2 evolution, oxygen uptake rate (OUR) was observed to asses the stability of compost. The CO2 evolution rates for C/N ratio 16, 22, 30 and 38 decreased from initial values of 7.88, 7.24, 7.01 and 7.89 mg/g VS/day to 0.76, 0.84, 1.24 and 2.37 mg/g VS/day, respectively, strongly reflecting the viability of rotary drum for various types of organic wastes waste with varying C/N ratios. On analyzing the results by ANOVA, the decrease in CO2 evolution varied significantly between the days (P