Sustainable Materials Management Research Articles

The emissions from co-firing of biomass and torrefied biomass with coal in a chain-grate steam boiler

ABSTRACTIn this study, biomass of rice straw (RS) and wood (WD) and their torrefied biomass (RST and WDT) were used as solid biofuel (SBF) for co-firing individually with coal in a commercial continuous chain-grate steam boiler system, which was conducted at fixed input rate of heating value of mixture of SBF and coal and at fixed airflow rate. The effects of key system parameters on the gaseous and particulate pollutions and ash were examined. These include SBF type and blending ratio (RBL) of biomass (i.e., SBF) in the mixture of coal and biomass based on heating values for co-firing.The results indicated that wood, which possesses high heating value while less amount of ash, is more suitable for co-firing with coal than rice straw. Torrefaction can increase the heating value of biomass and homogenize its property, being beneficial to co-firing. Also, torrefaction can decompose the hydroxyl group of biomass, which makes biomass tending to possess hydrophobicity. This, in turn, helps the storage and transportation of biomass. Generally, adding the RS (with RBL = 5-10%), WD (2-15%), RST (2-10%) and WDT (2-20%), respectively, with coal decreases the emissions of NOx and SO2, but increases that of CO (except RST). The emission of HCl is little. The addition of biomass also increases the emission of fine particulate matters (PM) especially PM2.5 in the flue gases, raising PM2.5/PM100 from 34.87 to 78.35 wt.% (Case 50%WDT). These emissions for the Cases tested satisfy with Taiwanese emission standards of stationary sources which set limitations of NOx, SO2, CO and HCl < 350, 300, 2000 and 80 ppmv, while PM < 50 mg/m3, respectively. The results support the use of RS, WD, RST and WDT for co-firing with coal.Implications: This study examined the suitability of using solid bio-fuels to co-fire with coal in an industrial chain-grate steam boiler system with a capacity of 100 kW, in order to achieve carbon-free emissions. Both biomass and torrefied biomass of solid bio-fuel were tested. The findings would be useful for proper design and rational operation of solid bio-fuel/coal co-firing combustion matching the appeal of sustainable material management and circular economy of biomass, and of adaptation of global warming induced by greenhouse gases. It also provides information for policy-makers to promote the co-firing application of biomass and related bio-waste materials.

YSTAFDB, a unified database of material stocks and flows for sustainability science

We present the Yale Stocks and Flows Database (YSTAFDB), which comprises most of the material stocks and flows (STAF) data generated at the Center for Industrial Ecology at Yale University since the early 2000s. These data describe material cycles, criticality, and recycling in terms of 62 elements and various engineering materials, e.g., steel, on spatial scales and timeframes ranging from cities to global and the 1800s to ca. 2013. YSTAFDB integrates this diverse collection of STAF data, previously scattered across various non-uniformly formatted electronic files, into a single data structure and file format. Here, we discuss this data structure as well as the usage and formatting of data records in YSTAFDB. YSTAFDB contains 100,000+ data records that are all situated in their systems contexts, with additional metadata included as available. YSTAFDB offers a comprehensive basis upon which STAF data can be accumulated, integrated, and exchanged, and thereby improves their accessibility. Therefore, YSTAFDB facilitates deeper understanding of sustainable materials use and management, which are key goals of contemporary sustainability science.

Approaches to integrate sustainable materials management into waste management planning and policy

Many solid waste policy makers are adopting sustainability practices following one of the three most commonly followed approaches: zero-waste, circular economy, and sustainable materials management (SMM). Although some communities have embraced these models, challenges remain to integrate these concepts into solid waste policy and planning. Several approaches for integrating SMM were demonstrated. The approaches centered on using SMM concepts to prioritize and strategically plan for more sustainable waste management and to create performance metrics to track solid waste management system progress. Waste information from five regions were compiled to assess current data adequacy; necessary data were in many cases limited. Findings showed that many of the regions will need to better track and report their individual materials generated and disposed of to more accurately apply SMM. Among the common outcomes of the SMM approaches illustrated was the need to better target specific materials in the waste stream for recovery, such as metal and paper products. Other findings included the need to more effectively promote and track waste reduction efforts given the dramatic beneficial outcomes when using an SMM-based performance metric, such as an energy use reduction goal.

Assessment of the potential of a circular economy in open economies – Case of Belgium

Interest from the research and policy community in the circular economy (CE) is growing. This research describes how the potential for a circular economy in open economies can be estimated by using different assessment methods. Methods and indicators have been selected that have a relevance for one or more of the public policy objectives for circular economy: Openness Index, economic structure, Balassa Index, value chain analysis, substitution potential of Sustainable Materials Management (SMM) strategies, waste treatment scenarios based on physical and hybrid Input-Output (IO) analysis. These methods differ in scope and degrees of complexity and are used at different assessment levels. The potential for a circular economy in this paper is assessed by evaluating the contribution to the public policy objectives for CE: resource efficiency, reduction of dependency on materials, competitiveness, creation of domestic jobs, reduced Greenhouse Gas (GHG) emissions. Results obtained by these methods are shown for Belgium and, in some cases, compared to the results of other countries to illustrate the differences between economies. CE activities (in response to public policy objectives) will enhance the ongoing trend of reducing the share of primary sectors in economies. The openness of an economy is expressed as the ratio of sum of import and export and Gross Domestic Product (GDP). Imported products add to the potential of domestic closed-loop circular initiatives like re-use, repair, remanufacture, recycling, but this will require knowledge about composition and spare part availability. Exported products are no longer available for these domestic CE initiatives, reducing the domestic potential for CE and the domestic export activity is vulnerable to CE activities abroad. Especially the increasing geographical distance in trade complicates the practical and legal barriers to close the loop. In open economies, both global and domestic substitution effects due to new circular economy policy initiatives are important to consider.

Reusing Food Waste in Food Manufacturing Companies: The Case of the Tomato-Sauce Supply Chain

The importance of reducing food loss and waste (FLW) has recently been emphasized at a European level with the amendment to the European Waste Framework Directive, according to which the effective reduction of food waste can be carried out by adopting a circularity approach that facilitates the transition to more sustainable management of materials. Likewise, the importance of concentrating on FLW produced within specific food supply chains has emerged as an effective starting point for quantifying the overall amount of wastage produced, emphasizing possible prevention actions as well as re-using and valorising waste. From this perspective, our study focuses on the tomato-sauce supply chain with a threefold aim. Firstly, to quantify the amount of FLW generated along the tomato-sauce supply chain from cultivation to retail; secondly, to understand the most important related causes; and thirdly, to assess if and to what extent FLW can be reused according to the Circular Economy (CE) approach. By adopting the Food Loss and Waste Accounting and Reporting Standard, the analyses focused on the production of the Barilla Tomato and Basil sauce in Italy, as well as the related inventory. It was revealed that this supply chain can be considered an example of a true circular economy, in which almost nothing is lost because more than 85% of the total FLW are valorized into alternative sectors or activities.

Investigating and optimizing the mix proportion of sustainable phosphate-based rapid repairing material

For solid waste disposal and cement consumption reduction, sustainable phosphate-based rapid repairing materials (sust-MPC) were prepared with MgO-containing by-products (LG-MgO) and circulating fluidized bed (CFB) fly ash. The effects of various mix proportions on the fluidity, setting time and mechanical properties of sust-MPC were investigated. Based on that, mix proportion optimization procedure has been developed according to the multi-objective comprehensively considering. The results showed that the MgO to KDP ratio (M/P) was the most influential parameter on the fluidity, whereas the Borax dosage (B/MPF) and Water-to-binder ratio (W/MPF) were the dominant factors on the setting time and 1-h mechanical properties, respectively. Yet, the effect of CFB fly ash addition (CFB/MPF) was relatively small. Finally, the performance comparisons of sust-MPC and conventional MPC were carried out. Examined properties included basic properties, adhesion strength and microstructure, etc. Overall, sust-MPC has shown a better behavior. These positive results indicated that sust-MPC could be a promising alternative in developing sustainable construction material and waste management as well.

Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites.

The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (Pinus sylvestris L.) sapwood with sodium silicate and TiO2 nanoparticles via vacuum-pressure technique is reported. Pyrolysis of modified wood was studied by TG-FTIR analysis; the results showed that maximum weight loss for the modified wood was obtained at 40–50 °C lower temperatures compared to the reference untreated wood. The Gram–Schmidt profiles and spectra extracted at maxima absorption from Gram–Schmidt plots indicated chemical changes in wood–inorganic composites. SEM/EDS analysis revealed the presence of Na–O–Si solid gel within the wood-cell lumen and showed that TiO2 was homogeneously distributed within the amorphous Na–O–Si glass-forming phase to form a thin surface coating. EDS mapping further revealed the higher diffusivity of sodium into the cell wall compared to the silicon compound. The presence of amorphous sodium silicate and nano-TiO2 was additionally confirmed by XRD analysis. FTIR spectra confirmed the chemical changes in Scots pine sapwood induced by alkalization. Brinell hardness test showed that the hardness of the modified wood increased with the highest value (44% increase in hardness) obtained for 10% Na2SiO3–nTiO2 modified wood. The results showed good correlation between TG and flammability test; limiting oxygen index (LOI) values for the wood–inorganic composites increased by 9–14% compared to the untreated wood.

A Pilot Plant Study on the Autoclaving of Food Wastes for Resource Recovery and Reutilization

Autoclaving of food wastes (FW) for the resource recovery and reutilization was studied using the pilot plant scale. Experiments were conducted at various temperatures of 408, 428, and 438 K and times of 15 and 60 min. The in-filled steam to the autoclave was supplied by the incineration plant with a gauge pressure of 7 kg/cm2 and a temperature of 443 K or above. The results obtained from the experiments show that the less energy- and time-consuming autoclaving conditions (408 K and 15 min, denoted as Case A408-15) are effective. Comparisons of the properties and characteristics of autoclaved FW (FWA) of Case A408-15 with those of FW are made. The wet bulk volume and wet bulk density of FW A are dramatically reduced to 15.64% and increased to 313.37% relative to those of FW, respectively. This makes the subsequent processing and reuse for FWA more convenient than FW. The autoclaving results in an increase of carbon content and a decrease of nitrogen content, and thus an increase of the C/N ratio of FWA. The contents of sulfur, hemi-cellulose, and cellulose of FWA are also reduced. All these fluctuations are beneficial for making compost or other usages from FWA than FW. The autoclaved liquid product (LA) separated from FWA and liquid condensate (LC) from the released gas possess high COD and TOC. These two liquids can be mixed for use as liquid fertilizers with proper conditioning. Alternatively, further anaerobic digestion of the mixture of FWA, LA, and LC can offer enhanced biogas production for power generation. All these thus match the appeal of sustainable materials management and circular economy. The emitted gas from autoclaving contains no CO and some hydrocarbons. Suitable air pollution control is needed. The results and information obtained are useful for the proper recovery and reuse of abundant food wastes from domestic households and food industries.

A review of the properties of recycled and waste materials for energy refurbishment of existing buildings towards the requirements of NZEB

In Europe buildings account for 40% to 50% of total energy consumption and the largest greenhouse gases emitters and urgent measures and valid instruments are therefore required to improve energy saving, use of renewable sources in moving towards a sustainable materials management where waste becomes a “resource”. In this context, there is an increase in research into development and manufacturing of new eco-friendly building envelope components from recycled and waste materials as high value-added good circular economy practice. Waste management may have significant effects in the sector of sustainable building the ultimate objective being the alternative construction materials replacing traditional materials: the development of innovative techniques aims to incorporate wastes into the production of building materials – for examples rubber, fly ash and sludge, etc. – to enhance thermal insulation properties. An effort in the sustainability in building design process is to develop researches aimed at enhancing thermal performance of components using materials capable of reusing a high waste content. The goal of this paper is to examine the technical feasibility of using inert waste materials from the combustion of municipal solid waste or solid recovered fuel and highlight changes in thermal characteristics (thermal conductivity, specific heat and density) by adding recycled and waste materials to the construction materials. The paper explores the potential of the use of thus obtained materials for the energy-refurbishment of existing buildings or with the challenge of meeting stringent energy consumption limits which are typical of a NZEB (net-zero energy building).

Environmental and technical feasibility study of upcycling wood waste into cement-bonded particleboard

The scarceness of virgin resources and sustainable management of waste materials in high-density city arouse heightened focus on new technology development for waste recycling and local utilization. Wood waste recovery from construction activities and upcycling into secondary products allow the substitution of virgin resources and minimize the environmental burdens within the frontier of industrial ecology. This study assessed the technical viability and environmental sustainability of cement-bonded particleboards (CBPs) produced with recycled wood aggregates and alternative binder; and compared the performance of its counterpart produced with virgin wood and ordinary binder using experimental analysis and life cycle assessment (LCA). The experimental results showed acceptable mechanical performance of the developed CBPs in compliance with the required standards. Adoption of carbon dioxide curing technology further enhanced the durability of the developed CBPs. Although similar greenhouse gases (GHGs) emission was observed for imported conventional CBPs and locally produced CBPs with alternative materials, the considerations of direct carbon sequestration and landfill avoidance contributed to a 9% reduction of the total GHGs compared to conventional CBPs. The LCA results also demonstrated that substantial amount of GHGs can be potentially saved depending on the recycling rates of wood waste in Hong Kong. Hence, technological innovation can effectively address problem of wood waste disposal and enhance material utilization and sustainability of the construction industry.

Patterns in municipal food scrap programming in mid-sized U.S. cities

In recent years there has been a modest but noticeable surge of interest from U.S. cities in the diversion of food scraps and other organic wastes from the municipal solid waste stream. Using a unique data set gathered through a survey of mid-sized U.S. cities in 2015, this article examines patterns in food scrap management at the municipal level. Specifically, it studies the extent to which there are shared characteristics among those places most likely to develop municipal capacity for food scrap diversion, and how these patterns can inform policy makers eager to migrate to more sustainable materials management at the local level. We utilize a logistic regression model to test the relationships between two types of food scrap diversion capacities and both socio-economic and municipal waste system characteristics. We find that socio-economic characteristics have limited correlation with the presence of food scrap programming in general in mid-sized cities. Cities with yard waste collection and unit-pricing, on the other hand, are more likely to also have any food scrap diversion programs. We find further that, in mid-sized cities, population density is positively correlated with the curbside collection of food scraps, as is the presence of unit-pricing, while cities that have retained source-separated curbside recycling programs are less likely to have curbside food scrap collection.

USEEIO: A new and transparent United States environmentally-extended input-output model

National-scope environmental life cycle models of goods and services may be used for many purposes, not limited to quantifying impacts of production and consumption of nations, assessing organization-wide impacts, identifying purchasing hotspots, analyzing environmental impacts of policies, and performing streamlined life cycle assessment. USEEIO is a new environmentally-extended input-output model of the United States fit for such purposes and other sustainable materials management applications. USEEIO melds data on economic transactions between 389 industry sectors with environmental data for these sectors covering land, water, energy and mineral usage and emissions of greenhouse gases, criteria air pollutants, nutrients and toxics, to build a life cycle model of 385 US goods and services. In comparison with existing US models, USEEIO is more current with most data representing year 2013, more extensive in its coverage of resources and emissions, more deliberate and detailed in its interpretation and combination of data sources, and includes formal data quality evaluation and description. USEEIO is assembled with a new Python module called the IO Model Builder capable of assembling and calculating results of user-defined input-output models and exporting the models into LCA software. The model and data quality evaluation capabilities are demonstrated with an analysis of the environmental performance of an average hospital in the US. All USEEIO files are publicly available bringing a new level of transparency for environmentally-extended input-output models.

Effectiveness of sewage sludge ash combined with waste pozzolanic minerals in developing sustainable construction material: An alternative approach for waste management

Utilization of the sewage sludge ash in fabricating the construction material would be an effective alternative approach under the sludge management scheme other than landfilling. The present investigation deals with the utilization of the recycled sewage sludge ash (SSA) combined with the quicklime (QL) and blast furnace slag (BFS) as a cementitious material in controlling the physical and mechanical performances of mortar. The mortar samples were prepared using the different amount of SSA, QL, BFS, and alkali activator (AA). The performance of the sewage sludge ash based mortar (SAM) was evaluated measuring the bulk density, apparent porosity, compressive strength, flexural strength, and shrinkage strain, etc. The result reveals that the higher dose of AA (50% weight w.r.t the volume of water used) and QL (20% w.r.t. weight of the total cementitious material) influences the mechanical strength of SAM. Additionally, the optimum dose of the BFS (10% w.r.t. weight of the total cementitious material) leads to yield a maximum compressive strength (31.3 MPa) of SAM. Finally, based on the analytical analysis, a model has been proposed to explain the overall performance of the SAM. Hence, the utilization of SSA (70%) combined with QL (20%) and BFS (10%) for the fabrication of mortar and concrete is assumed to be an effective alternative technique in developing sustainable construction material and waste management as well.

Resource and waste-stream modeling and visualization as decision support tools for sustainable materials management

Sustainable Materials Management requires the knowledge of complex material flow system. However, it's difficult for the policy maker and industries to know the flows for the lack of the expertise to implement material flow analysis. Facing this issue, we designed a web-based tool to generate interactive Sankey diagrams for developing strategies to sustainably manage resource and waste flows through a complex economy. By examining the opportunities across a material's lifecycle, this tool supports sustainable materials management, which is important in reducing environmental pressures and the demand for resource extraction. Three applications were developed for (1) tracking resource flows along supply chains, (2) identifying economic activities that cause waste generation, and (3) tracing the material footprints for a sector. To finish the applications, we integrated a comprehensive resource and waste database with several input–output analysis based material flow models. For easy recognition of the key flows and activities, Sankey diagrams can be generated using a data-visualization technology. This article demonstrates the material management practices that can be discovered with the information of the flow system from the applications. Examine the flow paths of resources, several practices for sand and gravels are formulated based on the key activities in processing or using the material. Overviewing the driving forces of industrial wastes, we also pinpoint the practices to reduce the generation of coal ash. Tracking the resource footprints of economic activities, we highlight that the construction sector can use the cement made from blast furnace slag as to reduce the footprint. Also, we explain how this approach facilitates the coordination of government's interagency actions and the engagement of private sectors.

An information system for sustainable materials management with material flow accounting and waste input–output analysis

Abstract Sustainable materials management focuses on the dynamics of materials in economic and environmental activities to optimize material use efficiency and reduce environmental impact. A preliminary web-based information system is thus developed to analyze the issues of resource consumption and waste generation, enabling countries to manage resources and wastes from a life cycle perspective. This pioneering system features a four-layer framework that integrates information on physical flows and economic activities with material flow accounting and waste input–output table analysis. Within this framework, several applications were developed for different waste and resource management stakeholders. The hierarchical and interactive dashboards allow convenient overview of economy-wide material accounts, waste streams, and secondary resource circulation. Furthermore, the system can trace material flows through associated production supply chain and consumption activities. Integrated with economic models; this system can predict the possible overloading on the current waste management facility capacities and provide decision support for designing strategies to approach resource sustainability. The limitations of current system are specified for directing further enhancement of functionalities.

Changing urban cement metabolism under rapid urbanization – A flow and stock perspective

China's rapid urbanization is characterized by large-scale construction activities which require enormous amounts of construction materials and induce a series of resource and environmental problems. However, few studies have paid serious attention to construction material metabolism within urban ecosystems in the Chinese urbanization hotspot. This study focuses on changes in cement metabolism in Xiamen from 2002 to 2012 and aims to elucidate its metabolic characteristics and mechanisms. The results show that, (1) residential buildings account for 1/3 of total cement use, with more and more accumulating as unused stock; (2) decoration is the second largest cement consumer after building and should be paid more attention in metabolism analyses; (3) road transport infrastructure is expected to maintain its growing potential for cement use; (4) increasing amounts of construction and demolition waste are hardly reused or recycled. To mitigate ecological pressures resulting from urban cement metabolism and foster sustainable construction, a multidimensional policy portfolio is proposed including development of improved real estate policies, optimization of urban spatial patterns, popularization of decoration-binding residential buildings and premixed mortar usage, establishment of a waste recycling system, industrialization of the construction industry and the promotion of sustainable consumption. This empirical research provides a reference template for future sustainable construction material management studies in rapidly urbanizing areas elsewhere.

Drivers and Constraints of Critical Materials Recycling: The Case of Indium

Raw material criticality studies are receiving increasing attention because an increasing number of elements of great economic importance, performing essential functions face high supply risks. Scarcity of key materials is a potential barrier to large-scale deployment of sustainable energy and clean-tech technologies as resorting to several critical materials. As physical scarcity and geopolitical issues may present a barrier to the supply of critical metals, recycling is regarded as a possible solution to substitute primary resources for securing the long-term supply of critical metals. In this paper, the main drivers and constraints for critical materials recycling are analyzed from literature, considering indium as a case study of critical materials. This literature review shows that waste electrical and electronic equipment (WEEE) could be a future source of critical metals; however, the reduction of dissipation of critical materials should have much higher priority. It is put forward that more attention should be paid to sustainable management of critical materials, especially improved practices at the waste management stage. This calls for not only more efficient WEEE recycling technologies, but also revising priorities in recycling strategies.

Using Green Chemistry and Engineering Principles To Design, Assess, and Retrofit Chemical Processes for Sustainability.

The concepts of green chemistry and engineering (GC&E) have been promoted as an effective qualitative framework for developing more sustainable chemical syntheses, processes, and material management techniques. This has been demonstrated by many theoretical and practical cases. In addition, there are several approaches and frameworks focused on demonstrating that improvements were achieved through GC&E technologies. However, the application of these principles is not always straightforward. We propose using systematic frameworks and tools that help practitioners when deciding which principles can be applied, the levels of implementation, prospective of obtaining simultaneous improvements in all sustainability aspects, and ways to deal with multiobjective problems. Therefore, this contribution aims to provide a systematic combination of three different and complementary design tools for assisting designers in evaluating, developing, and improving chemical manufacturing and materials management systems under GC&E perspectives. The WAR Algorithm, GREENSCOPE, and SustainPro were employed for this synergistic approach of incorporating sustainability at early stages of process development. In this demonstration, simulated ammonia production is used as a case study to illustrate this advancement. Results show how to identify process design areas for improvements, key factors, multicriteria decision-making solutions, and optimal trade-offs. Finally, conclusions were presented regarding the tools' use in more robust sustainable process and material management designs.

Material Stock Demographics: Cars in Great Britain.

Recent literature on material flow analysis has been focused on quantitative characterization of past material flows. Fewer analyses exist on past and prospective quantification of stocks of materials in-use. Some of these analyses explore the composition of products' stocks, but a focus on the characterization of material stocks and its relation with service delivery is often neglected. We propose the use of the methods of human demography to characterize material stocks, defined herein as stock demographics, exploring the insights that this approach could provide for the sustainable management of materials. We exemplify an application of stock demographics by characterizing the composition and service delivery of iron, steel, and aluminum stocks of cars in Great Britain, 2002-2012. The results show that in this period the stock has become heavier, it is traveling less, and it is idle for more time. The visualization of material stocks' dynamics demonstrates the pace of product replacement as a function of its usefulness and enables the formulation of policy interventions and the exploration of future trends.

Moving up the Waste Hierarchy in Maine: Learning from “Best Practice” State-Level Policy for Waste Reduction and Recovery

As Maine residents look toward the future, it is increasingly clear that more sustainable waste and materials management solutions will be necessary. A recent stakeholder engagement process involving nearly 200 industry professionals, municipal representatives and citizen groups confirmed this point. As we move together toward a more sustainable waste management system, participants in the engagement process identified an outstanding need to learn more about policies options. This article responds to that need with a review of state level policies designed to reduce waste generation and increase material recovery rates. We find there are a wide variety of state-level policy tools available, each of which involves a series of complex tradeoffs to balance decision criteria ranging from diversion potential and cost to social acceptability and environmental protection. While there is no magic formula, it is clear that the most successful state-level programs are those that utilize a variety of tools, selected as part of a comprehensive and data-driven long term planning process.