Furniture wood wastes: Experimental property characterisation and burning tests

Referring to the industrial wood waste category (as dominant in the provincial district of Pesaro-Urbino, Marche Region, Italy), this paper deals with the experimental characterisation and the carrying out of non-controlled burning tests (at lab- and pilot-scale) for selected “raw” and primarily “engineered” (“composite”) wood wastes.The property characterisation has primarily revealed the following aspects: potential influence on moisture content of local weather conditions at outdoor wood waste storage sites; generally, higher ash contents in “engineered” wood wastes as compared with “raw” wood wastes; and relatively high energy content values of “engineered” wood wastes (ranging on the whole from 3675 to 5105 kcal kg⁻¹ for HHV, and from 3304 to 4634 kcal kg⁻¹ for LHV).The smoke qualitative analysis of non-controlled lab-scale burning tests has primarily revealed: the presence of specific organic compounds indicative of incomplete wood combustion; the presence exclusively in “engineered” wood burning tests of pyrroles and amines, as well as the additional presence (as compared with “raw” wood burning) of further phenolic and containing nitrogen compounds; and the potential environmental impact of incomplete industrial wood burning on the photochemical smog phenomenon.Finally, non-controlled pilot-scale burning tests have primarily given the following findings: emission presence of carbon monoxide indicative of incomplete wood combustion; higher nitrogen oxide emission values detected in “engineered” wood burning tests as compared with “raw” wood burning test; and considerable generation of the respirable PM₁ fraction during incomplete industrial wood burning.     

Modelling of environmental impacts from biological treatment of organic municipal waste in EASEWASTE

The waste-LCA model EASEWASTE quantifies potential environmental effects from biological treatment of organic waste, based on mass and energy flows, emissions to air, water, soil and groundwater as well as effects from upstream and downstream processes. Default technologies for composting, anaerobic digestion and combinations hereof are available in the model, but the user can change all key parameters in the biological treatment module so that specific local plants and processes can be modelled. EASEWASTE is one of the newest waste LCA models and the biological treatment module was built partly on features of earlier waste-LCA models, but offers additional facilities, more flexibility, transparency and user-friendliness. The paper presents the main features of the module and provides some examples illustrating the capability of the model in environmentally assessing and discriminating the environmental performance of alternative biological treatment technologies in relation to their mass flows, energy consumption, gaseous emissions, biogas recovery and compost/digestate utilization.     

An LCA model for waste incineration enhanced with new technologies for metal recovery and application to the case of Switzerland

A process model of municipal solid waste incinerators (MSWIs) and new technologies for metal recovery from combustion residues was developed. The environmental impact is modeled as a function of waste composition as well as waste treatment and material recovery technologies. The model includes combustion with a grate incinerator, several flue gas treatment technologies, electricity and steam production from waste heat recovery, metal recovery from slag and fly ash, and landfilling of residues and can be tailored to specific plants and sites (software tools can be downloaded free of charge). Application of the model to Switzerland shows that the treatment of one tonne of municipal solid waste results on average in 425 kg CO₂-eq. generated in the incineration process, and 54 kg CO₂-eq. accrue in upstream processes such as waste transport and the production of operating materials. Downstream processes, i.e. residue disposal, generates 5 kg CO₂-eq. Savings from energy recovery are in the range of 67 to 752 kg CO₂-eq. depending on the assumptions regarding the substituted energy production, while the recovery of metals from slag and fly ash currently results in a net saving of approximately 35 kg CO₂-eq. A similar impact pattern is observed when assessing the MSWI model for aggregated environmental impacts (ReCiPe) and for non-renewable resource consumption (cumulative exergy demand), except that direct emissions have less and no relevance, respectively, on the total score. The study illustrates that MSWI plants can be an important element of industrial ecology as they provide waste disposal services and can help to close material and energetic cycles.     

Pollution prevention at the 3M corporation: Case study insights into organizational incentives, resources, and strategies

3M initiated its “Pollution Prevention Pays” (3P) program in 1975 and is probably the U.S. corporation which has been most identified with using preventive strategies to reduce toxic releases. This case study draws on interviews conducted with representatives of 3M manufacturing plants and corporate staff to provide both an overview of 3M's pollution prevention efforts and explore the organizational dimensions of two types of pollution prevention projects. The analysis addresses two key questions: (1) what do 3M's accomplishments indicate about the potential for pollution prevention approaches? and (2) what are the organizational incentives, resources and strategies which underpin 3M's pollution prevention efforts?     

An integrated appraisal of energy recovery options in the United Kingdom using solid recovered fuel derived from municipal solid waste

This paper reports an integrated appraisal of options for utilising solid recovered fuels (SRF) (derived from municipal solid waste, MSW) in energy intensive industries within the United Kingdom (UK). Four potential co-combustion scenarios have been identified following discussions with industry stakeholders. These scenarios have been evaluated using (a) an existing energy and mass flow framework model, (b) a semi-quantitative risk analysis, (c) an environmental assessment and (d) a financial assessment. A summary of results from these evaluations for the four different scenarios is presented. For the given ranges of assumptions; SRF co-combustion with coal in cement kilns was found to be the optimal scenario followed by co-combustion of SRF in coal-fired power plants. The biogenic fraction in SRF (ca. 70%) reduces greenhouse gas (GHG) emissions significantly (～2500 g CO₂ eqvt./kg DS SRF in co-fired cement kilns and ～1500 g CO₂ eqvt./kg DS SRF in co-fired power plants). Potential reductions in electricity or heat production occurred through using a lower calorific value (CV) fuel. This could be compensated for by savings in fuel costs (from SRF having a gate fee) and grants aimed at reducing GHG emission to encourage the use of fuels with high biomass fractions. Total revenues generated from coal-fired power plants appear to be the highest (£95/t SRF) from the four scenarios. However overall, cement kilns appear to be the best option due to the low technological risks, environmental emissions and fuel cost. Additionally, cement kiln operators have good experience of handling waste derived fuels. The scenarios involving co-combustion of SRF with MSW and biomass were less favourable due to higher environmental risks and technical issues.     

A methodology to determine gaseous emissions in a composting plant

Environmental impacts associated to different waste treatments are of interest in the decision-making process at local, regional and international level. However, all the environmental burdens of an organic waste biological treatment are not always considered. Real data on gaseous emissions released from full-scale composting plants are difficult to obtain. These emissions are related to the composting technology and waste characteristics and therefore, an exhaustive sampling campaign is necessary to obtain representative and reliable data of a single plant. This work proposes a methodology to systematically determine gaseous emissions of a composting plant and presents the results obtained in the application of this methodology to a plant treating source-separated organic fraction of municipal solid waste (OFMSW) for the determination of ammonia and total volatile organic compounds (VOC). Emission factors from the biological treatment process obtained for ammonia and VOC were 3.9 kg Mg OFMSW⁻¹ and 0.206 kg Mg OFMSW⁻¹ respectively. Emissions associated to energy use and production were also quantified (60.5 kg CO₂ Mg OFMSW⁻¹ and 0.66 kg VOC Mg OFMSW⁻¹). Other relevant parameters such as energy and water consumption and amount of rejected waste were also determined. A new functional unit is presented to relate emission factors to the biodegradation efficiency of the composting process and consists in the reduction of the Respiration Index of the treated material. Using this new functional unit, the atmospheric emissions released from a composting plant are directly related to the plant specific efficiency.     

An environmentally sustainable decision model for urban solid waste management

The aim of this work is to present the structure and the application of a decision support system (DSS) designed to help decision makers of a municipality in the development of incineration, disposal, treatment and recycling integrated programs. Specifically, within a MSW management system, several treatment plants and facilities can generally be found: separators, plants for production of refuse derived fuel (RDF), incinerators with energy recovery, plants for treatment of organic material, and sanitary landfills. The main goal of the DSS is to plan the MSW management, defining the refuse flows that have to be sent to recycling or to different treatment or disposal plants, and suggesting the optimal number, the kinds, and the localization of the plants that have to be active. The DSS is based on a decision model that requires the solution of a constrained non-linear optimization problem, where some decision variables are binary and other ones are continuous. The objective function takes into account all possible economic costs, whereas constraints arise from technical, normative, and environmental issues. Specifically, pollution and impacts, induced by the overall solid waste management system, are considered through the formalization of constraints on incineration emissions and on negative effects produced by disposal or other particular treatments.     

Past, present, and future of MSW landfills in Japan

This article focuses on the historical development of landfill technology since the beginning of the nineteenth century in Japan. The regulations and guidelines that form a framework for the technology are reviewed, and the historical background and the current state of Japanese municipal solid waste (MSW) management are described. Through the analysis of data collected from facility leaflets, changes in the leachate treatment system are surveyed. Finally, the concept of the “sustainable bioreactor landfill with low organics” is proposed.     

Reduction of CO2-emissions by using biomass in combustion and digestion plants

Climate protection is one of the main aims of environmental policy. One way to advance and push the progress is to reduce the use of fossil fuels for energy production through an increasing production of renewable and CO₂-neutral energy for example through application of biomass. This paper sets the focus on biomass streams that can be used both thermal and biological for energy production like grass or energy crops. To calculate the potentials of decrease of CO₂-emissions for treatment of biomass in either combustion or digestion plants some scenarios were set up with different assumptions regarding degree of efficiency of treatment plants which depends on size of plants and the treatment process itself. The energetic utilisation of the considered biomass streams is divided in different utilisation scenarios: combined heat and power generation (CHP) and heat generation or power generation only. Additionally four groups of plant sizes referring to electrical power (from 0.1 up to 10.0 MW) were taken into consideration. The calculations of potential savings of CO₂-emission in both types of treatment scenarios lead to the result that in comparison to biological technologies thermal processes show a much higher utilisation of the energy content in biomass.     

Injection Molded Biocomposites from Soy Protein Based Bioplastic and Short Industrial Hemp Fiber

Biocomposites from soy based bioplastic and chopped industrial hemp fiber were fabricated using twin-screw extrusion and injection molding process. Soy based bioplastics were prepared through cooking with plasticizer and blending with biodegradable poly(ester amide). Mechanical, thermal properties and fracture surface morphology of the “green”/biocomposites were evaluated with universal testing system (UTS), dynamic mechanical analysis (DMA), Environmental Scanning Electron Microscopy (ESEM). It was found that the tensile strength and modulus, flexural strength and modulus, impact strength and heat deflection temperature of industrial hemp fiber reinforced biocomposites significantly improved. The fracture surfaces showed no signs of matrix on the fiber surface suggesting poor interfacial adhesion.     

The use of silver as a selective precipitant for I in radioactive waste management

¹²⁹I is one of the more hazardous nuclides occurring in radioactive waste. In the form of I⁻, its most likely speciation, it is poorly sorbed on most geologic media. Several workers have suggested the use of silver to precipitate I⁻ as the insoluble AgI, in a cemented waste form, or as a “getter”. The efficacy of this procedure is examined by experiment, in conjunction with thermodynamic predictions.The addition of AgNO₃ to Portland cement leads to coprecipitation with C-S-H, with low Ag solubilities ( 10 μmg/L); 2–;3 orders of magnitude lower than predicted (from Ag₂O). AgI is stable in these matrices, with low aqueous I concentrations (<2 mg/L). In 85% BFS-15% OPC pastes, AgI is unstable due to redox and complexation reactions, with much I⁻ passing into solution; concentrations up to 900 mg/L were observed. It is shown that repository conditions, on closure, are also likely to induce solubilisation of I⁻ from AgI. It is concluded that the use of Ag is unlikely to significantly improve the immobilisation properties of the near field for radioiodine.     

Life cycle assessment of solid refuse fuel production from MSW in Korea

Solid refuse fuel (SRF) produced from waste materials is a promising fuel that can be utilized for energy recovery in industries. This study considered both characterization and weighting modeling as life cycle assessment (LCA) results. This study aimed to analyze the flows of materials and energy and to evaluate the environmental impact of SRF plants using LCA and compared them with an incineration plant. Based on the results of material and energy flow analysis, SRF products had various energy potentials depending on the treatment method of municipal solid waste (MSW) and replaced the current fossil fuels by SRF combustion. Global impacts were mainly influenced by energy consumption, especially drying methods in the production of SRF, and affected the results of the weighting analysis. The SRF plant with a bio-drying option was evaluated as the best effective practice in the weighting analysis. The LCA results in this study indicated 0.021–9.88 points according to drying methods for SRF production and 1.38 points for incineration. In the sensitivity analysis, the environmental impact of SRF production was found to be significantly affected by the drying methods for MSW and the utilization of fossil energy. Thus, improvement of the drying options could significantly reduce the environmental impact.     

Framework for estimating potential wastes and secondary resources accumulated within an economy – A case study of construction minerals in Japan

Material stocks in economic society are considered to represent a reserve for wastes and secondary resources. From the viewpoints of proper disposal and reutilization of stocked materials, accurate estimation of the amount of materials that will emerge as wastes or secondary resources in the future is important. We defined materials that have a high probability of emerging as wastes or secondary resources as “potential wastes and secondary resources” and estimated that amount for construction minerals in Japan as a case study. The following conclusions were drawn. (1) We classified materials that are input into economic society into four categories: potential wastes and secondary resources, potential dissipated materials, dissipatively used materials, and permanent structures. By clarifying the latter three non-potential wastes and secondary resources, we performed a more accurate assessment of the wastes and secondary resources that will emerge in the future. (2) The share of potential wastes and secondary resources was estimated to be about 30% of all construction minerals that have been input into and accumulated in Japanese economic society. (3) Information related to potential dissipated materials and dissipatively used materials will provide fundamental knowledge to support analyses of the environmental impacts and resource losses which these materials might generate.     

Optimal utilization of waste-to-energy in an LCA perspective

Energy production from two types of municipal solid waste was evaluated using life cycle assessment (LCA): (1) mixed high calorific waste suitable for production of solid recovered fuels (SRF) and (2) source separated organic waste. For SRF, co-combustion was compared with mass burn incineration. For organic waste, anaerobic digestion (AD) was compared with mass burn incineration. In the case of mass burn incineration, incineration with and without energy recovery was modelled. Biogas produced from anaerobic digestion was evaluated for use both as transportation fuel and for heat and power production. All relevant consequences for energy and resource consumptions, emissions to air, water and soil, upstream processes and downstream processes were included in the LCA. Energy substitutions were considered with respect to two different energy systems: a present-day Danish system based on fossil fuels and a potential future system based on 100% renewable energy. It was found that mass burn incineration of SRF with energy recovery provided savings in all impact categories, but co-combustion was better with respect to Global Warming (GW). If all heat from incineration could be utilized, however, the two alternatives were comparable for SRF. For organic waste, mass burn incineration with energy recovery was preferable over anaerobic digestion in most impact categories. Waste composition and flue gas cleaning at co-combustion plants were critical for the environmental performance of SRF treatment, while the impacts related to utilization of the digestate were significant for the outcome of organic waste treatment. The conclusions were robust in a present-day as well as in a future energy system. This indicated that mass burn incineration with efficient energy recovery is a very environmentally competitive solution overall.     

Pyrolysis and gasification of meat-and-bone-meal: Energy balance and GHG accounting

Meat-and-bone-meal (MBM) produced from animal waste has become an increasingly important residual fraction needing management. As biodegradable waste is routed away from landfills, thermo-chemical treatments of MBM are considered promising solution for the future. Pyrolysis and gasification of MBM were assessed based on data from three experimental lab and pilot-scale plants. Energy balances were established for the three technologies, providing different outcomes for energy recovery: bio-oil was the main product for the pyrolysis system, while syngas and a solid fraction of biochar were the main products in the gasification system. These products can be used – eventually after upgrading – for energy production, thereby offsetting energy production elsewhere in the system. Greenhouse gases (GHG) accounting of the technologies showed that all three options provided overall GHG savings in the order of 600–1000 kg CO₂-eq. per Mg of MBM treated, mainly as a consequence of avoided fossil fuel consumption in the energy sector. Local conditions influencing the environmental performance of the three systems were identified, together with critical factors to be considered during decision-making regarding MBM management.     

The contemporary Asian silver cycle: 1-year stocks and flows

The stocks and flows of silver throughout the Asian economy for 1997 have been quantified, with major flows examined over their entire life cycle, including mining, production, fabrication, and manufacture, product use, and waste management. By compiling the findings of 11 country-level material flow analyses, a regional analysis was created. The reliability and availability of the data varied, with the most confidence given to the earlier life stages and the most uncertainty existing later. Overall, Asia is a net importer of silver, requiring nearly 7000 Mg of silver in 1997. Approximately 2200 Mg Ag are mined, and production waste totals about 640 Mg Ag. The flow of silver into use equals 9900 Mg Ag, with a considerable build-up of 7100 Mg Ag entering in-use stock. Silver waste sent directly to the environment, in addition to landfilled waste, totals 1600 Mg Ag. Much variation exists when examining country-level silver flows on a per capita basis. India and Thailand’s fondness for silver jewelry greatly increases their silver flows into use and in-use stock. Japan’s high overall consumption reflects its high GDP per capita. Regionally, a significant potential exists to tap the silver contained in the in-use stocks and to enhance the recycling rates.     

Alternative strategies for energy recovery from municipal solid waste Part B: Emission and cost estimates

This two-part paper assesses four strategies for energy recovery from Municipal Solid Waste (MSW) by dedicated Waste-To-Energy (WTE) plants. In strategy 1, the residue of Material Recovery (MR) is fed directly to a grate combustor, while in strategy 2 the grate combustor comes downstream of light mechanical treatment. In strategies 3 and 4, the MR residue is converted into Refuse Derived Fuel (RDF), in a fluidized cumbuster bed. The results of Part A, devoted to mass and energy balances, clearly show that pre-treating the MR residue in order to increase the heating value of the feedstock fed to the WTE plant has marginal effects on the energy efficiency of the WTE plant. When considering the efficiency of the whole strategy of waste management, the energy balances show that the more thorough the pre-treatment, the smaller the amount of energy recovered per unit of MR residue. Starting from the heat/mass balances illustrated in Part A, Part B examines the environmental impacts and economics of the various strategies by means of a Life Cycle Assessment (LCA). Results show that treating the MR residues ahead of the WTE plant does not provide environmental or economic benefits. RDF production worsens almost all impact indicators because it reduces net electricity production and thus the displacement of power plant emissions; it also increases costs, because the benefits of improving the quality of the material fed to the WTE plant do not compensate the cost of such improvement.     

Analysis of the combustion and pyrolysis of dried sewage sludge by TGA and MS

In this study, the combustion and pyrolysis processes of three sewage sludge were investigated. The sewage sludge came from three wastewater treatment plants.Proximate and ultimate analyses were performed. The thermal behaviour of studied sewage sludge was investigated by thermogravimetric analysis with mass spectrometry (TGA-MS). The samples were heated from ambient temperature to 800 °C at a constant rate 10 °C/min in air (combustion process) and argon flows (pyrolysis process). The thermal profiles presented in form of TG/DTG curves were comparable for studied sludges. All TG/DTG curves were divided into three stages. The main decomposition of sewage sludge during the combustion process took place in the range 180–580 °C with c.a. 70% mass loss. The pyrolysis process occurred in lower temperature but with less mass loss. The evolved gaseous products (H₂, CH₄, CO₂, H₂O) from the decomposition of sewage sludge were identified on-line.     

Material and energy recovery in integrated waste management systems: the potential for energy recovery

This article is part of a set of six coordinated papers reporting the main findings of a research project carried out by five Italian universities on "Material and energy recovery in Integrated Waste Management Systems (IWMS)". An overview of the project and a summary of the most relevant results can be found in the introductory article of the series. This paper describes the work related to the evaluation of mass and energy balances, which has consisted of three major efforts (i) development of a model for quantifying the energy content and the elemental compositions of the waste streams appearing in a IWMS; (ii) upgrade of an earlier model to predict the performances of Waste-to-Energy (WtE) plants; (iii) evaluation of mass and energy balances of all the scenarios and the recovery paths considered in the project. Results show that not only the amount of material available for energy recovery is significantly higher than the Unsorted Residual Waste (URW) left after Separate Collection (SC), because selection and recycling generate significant amounts of residues, but its heating value is higher than that of the original, gross waste. Therefore, the energy potential of what is left after recycling is always higher than the complement to 100% of the Source Separation Level (SSL). Also, increasing SSL has marginal effects on the potential for energy recovery: nearly doubling SSL (from 35% to 65%) reduces the energy potential only by one fourth. Consequently, even at high SSL energy recovery is a fundamental step of a sustainable waste management system. Variations of SSL do bring about variations of the composition, heating value and moisture content of the material fed to WtE plants, but these variations (i) are smaller than one can expect; (ii) have marginal effects on the performances of the WtE plant. These considerations suggest that the mere value of SSL is not a good indicator of the quality of the waste management system, nor of its energy and environmental outcome. Given the well-known dependence of the efficiency of steam power plants with their power output, the efficiency of energy recovery crucially depends on the size of the IWMS served by the WtE plant. A fivefold increase of the amount of gross waste handled in the IWMS (from 150,000 to 750,000 tons per year of gross waste) allows increasing the electric efficiencies of the WtE plant by about 6-7 percentage points (from 21-23% to 28.5% circa).     

Diffusion test of 20 kinds of waste molten slags and competitive materials

“Waste molten slag” is a glass-like material produced by the vitrification of solid waste or solid waste incineration residue. When using slags of this kind in a natural environment, their impact is anticipated to be at the same level as competitive or substituted materials. In this study, we made comparative evaluations between waste molten slags and competitive materials, using 20 samples in total. It was proved that release fluxes of metals from molten slags of municipal solid waste were almost at the same level as competitive or substituted materials. However, a larger impact will be caused from some types of slag that contain harmful metals in high concentrations, such as the slag from shredded automobile residues. The results of release flux showed that nearly 80% of the slope of the flux did not fit with the diffusion range. However, the linearity of every flux was extremely high, regardless of the slope.