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.     

Costs and benefits of packaging waste recycling systems

This Special Issue provides several different perspectives on the complex issue of packaging waste recycling. It comprises a diverse and rich set of contributions with insights from very different disciplines that range from economics to engineering. All types of “costs and benefits” are addressed in this collection of articles. In addition to the economic and strictly financial impacts of selective collection and sorting of packaging waste, several authors discuss other types of impacts, such as the environmental and social ones. The reader will find articles that address recycling systems as a whole, pieces that focus on specific impacts and detailed discussions of particular material streams or waste management strategies. The Special Issue represents an indispensable resource for academics, policy-makers and practitioners with interests in recycling and packaging waste management.     

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

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.     

Electronic waste recycling: A review of U.S. infrastructure and technology options

The useful life of consumer electronic devices is relatively short, and decreasing as a result of rapid changes in equipment features and capabilities. This creates a large waste stream of obsolete electronic equipment, electronic waste (e-waste).Even though there are conventional disposal methods for e-waste, these methods have disadvantages from both the economic and environmental viewpoints. As a result, new e-waste management options need to be considered, for example, recycling. But electronic recycling has a short history, so there is not yet a solid infrastructure in place.In this paper, the first half describes trends in the amount of e-waste, existing recycling programs, and collection methods. The second half describes various methods available to recover materials from e-waste. In particular, various recycling technologies for the glass, plastics, and metals found in e-waste are discussed. For glass, glass-to-glass recycling and glass-to-lead recycling technologies are presented. For plastics, chemical (feedstock) recycling, mechanical recycling, and thermal recycling methods are analyzed. Recovery processes for copper, lead, and precious metals such as silver, gold, platinum, and palladium are reviewed. These processes are described and compared on the basis of available technologies, resources, and material input–output systems.     

The effects on waste reduction and recycling rates when different components of the waste stream are counted

States differ in the components or solid waste management activities which they include when determining solid waste reduction and recycling rates. Thus, when attempting to draw comparisons among states, confusion arises in two ways: (1) use of two types of rates; and (2) use of different components or activities when calculating a given rate. This paper presents a mathematical basis for understanding the impacts on rate calculations when variations occur in the components and activities included in those calculations. Estimates of the incremental changes occurring in the rate calculations when incineration or selected components such as yard waste, construction and demolition wastes, and junked automobiles, are added to a base of municipal solid waste constituents are found using national data. Finally, the achieved rates reported by states counting different combinations are compared.     

Addressing criticality for rare earth elements in petroleum refining: The key supply factors approach

The group of elements known as the rare earth elements (REEs) is comprised of the 15 lanthanides. REEs are used in a number of technologies including catalysts for automobiles and petroleum refining, magnets for wind turbines and defense technologies, and phosphors in lighting and computer and TV screens. REEs are actually quite abundant in the earth′s crust. The elements are deemed “rare” because they are found in low concentrations and are difficult to extract economically. China holds 48% of the global REE reserves, and until 2012, production of REEs was almost exclusive to China. Over the past decade, China has been steadily decreasing its REE export quotas, reducing the supply of REEs available to the rest of the world. REEs are considered critical materials according to the National Science and Technology Council, which defines critical elements as those serving an essential function in the manufacture of a product, the absence of which would cause significant social consequence. Thus, it is extremely important for consumers of REEs to be aware of and understand the risks facing the supply REEs, as awareness is the first and most important step in developing strategies to mitigate risk. This report presents a mechanism for identifying the risks present in a supply–demand scenario and determining the criticality of an individual rare earth element under specific circumstances.     

An illicit economy: scavenging and recycling of medical waste

This paper discusses a significant illicit economy, including black and grey aspects, associated with medical waste scavenging and recycling in a megacity, considering hazards to the specific group involved in scavenging as well as hazards to the general population of city dwellers. Data were collected in Dhaka, Bangladesh, using a variety of techniques based on formal representative sampling for fixed populations (such as recycling operatives) and adaptive sampling for roaming populations (such as scavengers). Extremely hazardous items (including date expired medicines, used syringes, knives, blades and saline bags) were scavenged, repackaged and resold to the community. Some HCE employees were also observed to sell hazardous items directly to scavengers, and both employees and scavengers were observed to supply contaminated items to an informal plastics recycling industry. This trade was made possible by the absence of segregation, secure storage and proper disposal of medical waste. Corruption, a lack of accountability and individual responsibility were also found to be contributors. In most cases the individuals involved with these activities did not understand the risks. Although motivation was often for personal gain or in support of substance abuse, participants sometimes felt that they were providing a useful service to the community.     

The future place of recycling in household waste policy: the case of France

To be rightly implemented, an environmental policy ought to set an institutional framework (goals, rules and instruments) which incents decentralised actors to adopt the appropriate range of technologies. In the household waste management policy, the development of valorisation techniques (and particularly recycling) must be supported by convenient instruments and incentives. The paper analyses the problems encountered with the French household waste policy to ensure the takeoff of recycling techniques. At the moment, a rather under-proportioned institutional setting leads to favour the adoption of incineration with energy recovery at the expenses of recycling. This tends to create a structural bias in favour of incineration.     

Characterization of waste materials originating from Quebec supermarkets and an assessment of recycling potential

This study evaluated, both qualitatively and quantitatively, waste materials from several major Quebec grocery stores. Averaged over nine sampling dates, cardboard, paper and wood products represented 43 and 74% of waste material, based on weight and volume, respectively while organic matter including fruits, vegetables, baked goods and meat products represented 40 and 10% of waste material based on weight and volume. Plastics, wrapping and bagging materials, represented over 7 and 13% of waste material based on weight and volume, respectively, and other recyclable waste materials such as glass, metal and various miscellaneous objects, represented 4 and 2% of waste material based on weight and volume. On average, 60.6 kg waste/employee per week was generated by the three stores. Store size was not a determining factor in the composition of grocery store waste material. These results suggest that costs associated with supermarket waste disposal may be substantially reduced by source-separation of recyclable and compostable materials while reducing pressure for incineration or landfill. Therefore, the adoption of recycling and source-separation programs, and studies to determine problems and costs associated with the implementation of such programs are recommended.     

Economic viability of packaging waste recycling systems: A comparison between Belgium and Portugal

The Packaging and Packaging Waste Directive has had an undeniable impact on waste management throughout the European Union. Whereas recycling and recovery targets are the same, member states still enjoy a considerable degree of freedom with respect to the practical organization and management strategies adopted. Nevertheless, in all cases, the industry (which brings packaging material onto the market) should be responsible for the costs associated with packaging waste recycling/recovery (following the extended producer responsibility principle). The current paper compares and contrasts the institutional frameworks and financial costs and benefits of waste management operators for Belgium and Portugal. The unit costs of selective collection and sorting of packaging waste are provided for both countries. In Belgium, the costs of recycling seem to be fully supported by the industry (through Fost Plus, the national Green Dot agency). In Portugal the fairness of the recycling system depends on the perspective adopted (economic or strictly financial). Adopting a strictly financial perspective, it seems that Sociedade Ponto Verde (SPV, the Portuguese Green Dot agency) should increase the transfers to local authorities. However, the conclusions differ for this country if the avoided costs with refuse collection and other treatment are taken into account.     

PET containers in Brazil: Opportunities and challenges of a logistics model for post-consumer waste recycling

The use of post-consumer materials is directly related to reducing the cost of production and extraction of natural resources. Non-recyclable materials are randomly disposed in the environment. Brazil is one of the largest consumers of PET (polyethylene terephthalate) bottles. The purpose of this paper is to describe the opportunities and challenges of the logistics model for post-consumer PET bottle recycling in Brazil, while providing knowledge of its practices along the recycling chain. The results describe the need to educate those directly and indirectly involved in the process; to reduce consumption in order to reduce the amount of waste generated; to structure the post-consumer reverse chain and engage industrial sectors and government, through public policies, to support cleaner technologies along the PET bottle production chain.     

Understanding the normalisation of recycling behaviour and its implications for other pro-environmental behaviours: A review of social norms and recycling

This paper examines our understanding of recycling behaviour in the context of its increasing normalisation in the UK. It reflects on the recent history of dry recycling (i.e. recycling of ‘dry’ materials such as paper, glass, plastics and cans) and asks the question as to what influence policy drivers and the increased provision of facilities for recycling have had on people's behaviour. In reviewing the evidence for recycling being considered a norm, this paper explores what influence norms, habit and identities have on recycling behaviour.It then considers what lessons the evidence offers for using the normalisation of recycling behaviour in influencing more people to recycle and to adopt other sustainable behaviours. The somewhat contentious issue of whether engaging in recycling behaviours has a positive or negative effect on people engaging with other pro-environmental behaviours is discussed. The evidence shows that both positive and negative spillover occurs and understanding where the balance lies, as well as what effect recycling being a norm plays in this, is important in determining appropriate interventions to influence pro-environmental behaviours. The paper concludes with some observations on implications of the evidence on intervention approaches to influence pro-environmental behaviours.     

Bioethanol from waste: Life cycle estimation of the greenhouse gas saving potential

This paper considers two alternative feedstocks for bioethanol production, both derived from household waste—Refuse Derived Fuel (RDF) and Biodegradable Municipal Waste (BMW). Life Cycle Assessment (LCA) has been carried out to estimate the GHG emissions from bioethanol using these two feedstocks. An integrated waste management system has been considered, taking into account recycling of materials and production of bioethanol in a combined gasification/bio-catalytic process. For the functional unit defined as the ‘total amount of waste treated in the integrated waste management system’, the best option is to produce bioethanol from RDF—this saves up to 196 kg CO₂ equiv. per tonne of MSW, compared to the current waste management practice in the UK.However, if the functional unit is defined as ‘MJ of fuel equiv.’ and bioethanol is compared with petrol on an equivalent energy basis, the results show that bioethanol from RDF offers no saving of GHG emissions compared to petrol. For example, for a typical biogenic carbon content in RDF of around 60%, the life cycle GHG emissions from bioethanol are 87 g CO₂ equiv./MJ while for petrol they are 85 g CO₂ equiv./MJ. On the other hand, bioethanol from BMW offers a significant GHG saving potential over petrol. For a biogenic carbon content of 95%, the life cycle GHG emissions from bioethanol are 6.1 g CO₂ equiv./MJ which represents a saving of 92.5% compared to petrol. In comparison, bioethanol from UK wheat saves 28% of GHG while that from Brazilian sugar cane – the best performing bioethanol with respect to GHG emissions – saves 70%. If the biogenic carbon of the BMW feedstock exceeds 97%, the bioethanol system becomes a carbon sequester. For instance, if waste paper with the biogenic carbon content of almost 100% and a calorific value of 18 MJ/kg is converted into bioethanol, a saving of 107% compared to petrol could be achieved. Compared to paper recycling, converting waste paper into bioethanol saves 460 kg CO₂ equiv./t waste paper or eight times more than recycling.     

Present status of the recycling of waste electrical and electronic equipment in Korea

In Korea due to rapid economical growth followed by urbanisation, breakage of large traditional families into small nuclear families, continuous changes in equipment features and capabilities causes tremendous increase in sale of new electrical and electronic equipment (EEE) and decrease in sale of used EEE. Subsequently, the ever-increasing quantity of waste electrical and electronic equipment (WEEE) has become a serious social problem and threat to the environment. Therefore, the gradual increase in the generation of WEEE intensifies the interest for recycling to conserve the resources and protect the environment. In view of the above, a review has been made related to the present status of the recycling of waste electrical and electronic equipment in Korea. This paper describes the present status of generation and recycling of waste electrical and electronic equipment, namely TVs, refrigerators, washing machines, air conditioners, personal computers and mobile phones in Korea. The commercial processes and the status of developing new technologies for the recycling of metallic values from waste printed circuit boards (PCBs) is also described briefly. Since 1998, three recycling centers are in full operation to recycle WEEE such as refrigerators, washing machines and air conditioners, having the total capacity of 880,000 units/year. All waste TVs are recently recycled on commission basis by several private recycling plants. The recycling of waste personal computers and mobile phones is insignificant in comparison with the amount of estimated obsolete those. Korea has adopted and enforced the extended producer responsibility (EPR) system. Korea is making consistent efforts to improve the recycling rate to the standards indicated in the EU directives for WEEE. Especially environmentally friendly and energy-saving technologies are being developed to recycle metal values from PCBs of WEEE.     

Phosphorus recovery and recycling from waste: An appraisal based on a French case study

Phosphate rocks, used for phosphorus (P) fertilizer production, are a non-renewable resource at the human time scale. Their depletion at the global scale may threaten global food and feed security. To prevent this depletion, improved P resource recycling from food chain waste to agricultural soils and to the food and feed industry is often presented as a serious option. However, waste streams are often complex and their recycling efficiency is poorly characterized. The aim of this paper is to estimate the P recovery and recycling potential from waste, considering France as a case study. We assessed the P flows in food processing waste, household wastewater and municipal waste at the country scale using a substance flow analysis for the year 2006. We also quantified the P recycling efficiency as the fraction of P in waste that ultimately reached agricultural soils or was recycled in the food and feed industry. Efforts were made to limit data uncertainty by cross-checking multiple data sources concerning P content in waste materials. Results showed that, in general, P recovery in waste was high but that the overall P recycling efficiency was only 51% at the country scale. In particular, P recycling efficiency was 75% for industrial waste, 43% for household wastewater and 47% for municipal waste. The remaining P was discharged into water bodies or landfilled, causing P-induced environmental problems as well as losses of nutrient resources. Major P losses were through food waste (which amounted to 39% of P in available food) and treated wastewater, and the findings were confirmed through cross-checking with alternative data sources. Options for improving P resource recycling and, thereby, reducing P fertilizer use were quantified but appeared to be less promising than scenarios based on reduced food waste or redesigned agricultural systems.     

Mixed signals: market incentives, recycling, and the price spike of 1995

Environmental economics assumes that reliance on price signals, adjusted for externalities, normally leads to efficient solutions to environmental problems. We explore a limiting case, when market volatility created ‘mixed signals’: prices of waste paper and other recycled materials were suddenly extremely high in 1994–1995, then plummeted back to traditional low levels in 1996. These rapid reversals resulted in substantial economic and political costs. A review of academic and business literature suggests six possible explanations for abrupt price spikes. An econometric analysis of the prices of wood pulp and waste paper shows that factor which explained price changes in 1983–1993 contribute very little to understanding the subsequent price spike. From the econometric analysis and from other sources, we conclude that speculation must have played a major role in the price spike, perhaps in combination with modest effects from changes in government policy and in export demand. If speculatively driven price spikes can disrupt an environmentally important industry such as recycling, what is the appropriate role for public policy? When price volatility is sufficiently disruptive, then measures to control or stabilize prices, rather than interfering with the market, might help to make it more efficient.     

Junk-buyers as the linkage between waste sources and redemption depots in urban China: the case of Wuhan

This paper locates junk-buyers in the recycling chain that includes waste source, collection system and end-user. With increasing needs of convenience for recycling at waste sources but disappearing redemption depots in city blocks of China, junk-buyers play a role of linkage between waste sources and redemption depots. It is these door-to-door collectors who make the general public aware of cash value inside recyclable waste. Also, the motivation of getting cash back pushes junk-buyers become immediate suppliers to redemption depots. Without junk-buyers as door-to-door collectors, the current waste recovery system in post-Mao's China would brake down. However, as in other developing countries, the junk-buyer occupation in urban China currently is typically driven by economic incentives, and the door-to-door collection of recyclable waste completely falls into junk-buyer individual business. It is difficult for junk-buyers who mainly come from the countryside to establish stable relations with waste sources for lack of recognition from urban society. The appropriate allocation of individual time and space becomes crucial to conducting the door-to-door activities so as to collecting more recyclables. While the collecting territory as the condition of production is positively reflected by the usual extent of the collecting distance, junk-buyers mostly spend time in finding sellers instead of simply expanding their collecting territory. This is a typical example of the cheapest and lowest skilled labor forces being in relatively unlimited supply in a developing country.     

Identifying the key factors in increasing recycling and reducing residual household waste: a case study of the Flemish region of Belgium

The competent waste authority in the Flemish region of Belgium created the 'Implementation plan household waste 2003-2007' and the 'Implementation plan sustainable management 2010-2015' to comply with EU regulation. It incorporates European and regional requirements and describes strategies, goals, actions and instruments for the collection and treatment of household waste. The central mandatory goal is to reduce and maintain the amount of residual household waste to 150 kg per capita per year between 2010-2015. In literature, a reasonable body of information has been published on the effectiveness and efficiency of a variety of policy instruments, but the information is complex, often contradictory and difficult to interpret. The objective of this paper is to identify, through the development of a binary logistic regression model, those variables of the waste collection scheme that help municipalities to reach the mandatory 150 kg goal. The model covers a number of variables for household characteristics, provision of recycling services, frequency of waste collection and charging for waste services. This paper, however, is not about waste prevention and reuse. The dataset originates from 2003. Four out of 12 variables in the model contributed significantly: income per capita, cost of residual waste collection, collection frequency and separate curbside collection of organic waste.     

Overview of household solid waste recycling policy status and challenges in Malaysia

With the annual increase in waste generation and heavy reliance on landfilling as disposal, method in Malaysia, it is just a matter of time before significant problems of space limitations, health, and environmental issues hit the nation severely. This paper attempts to develop an overview on solid, waste recycling in Malaysia at the most basic level of a community or nation which is the household, unit. Households are the main primary source of municipal solid waste in Malaysia, consisting of, recyclable materials at most 70% to 80% of the total waste composition as found placed in the, landfills. Overview on the existing household solid waste recycling policy and program status in, Malaysia is relevant in enhancing solid waste management measure from recycling perspective. Despite the high potential and opportunities for solid waste recycling, wastes are still simply being, dumped in an open area of ground without any attempt for recovery and recycling. Comparing to, recycling rates of neighboring countries, Malaysia is falling back at merely 5% which proves how, uncommon recycling practice is. The government is committed to significantly improve the national's, solid waste management services especially in waste minimization. Fortunately the emphasis on, recycling as a sustainable waste management strategy has taken a shift in paradigm as wastes, separation and recycling are part of the major changes in the current policy implementation. With, issues and challenges in recycling practice that were highlighted in this context especially from the, aspects of information availability and other loopholes within solid waste management policies and, related recycling program within the community, the question on whether the goals in 2020 can be, met remains unsure of but there is a possibility for a successful implementation of sustainable solid, waste management particularly in recycling.     

A review on the use of waste glasses in the production of cement and concrete

The use of recycled waste glasses in Portland cement and concrete has attracted a lot of interest worldwide due to the increased disposal costs and environmental concerns. Being amorphous and containing relatively large quantities of silicon and calcium, glass is, in theory, pozzolanic or even cementitious in nature when it is finely ground. Thus, it can be used as a cement replacement in Portland cement concrete. The use of crushed glasses as aggregates for Portland cement concrete does have some negative effect on properties of the concrete; however, practicle applicability can still be produced even using 100% crushed glass as aggregates. The main concerns for the use of crushed glasses as aggregates for Portland cement concrete is the expansion and cracking caused by the glass aggregates. This paper summarizes the progresses and points out the directions for the proper uses of waste glasses in Portland cement and concrete.