Self-catalytic pyrolysis thermodynamics of waste printed circuit boards with co-existing metals

● The co-existing metals in WPCBs has positive catalytic influence in pyrolysis. ● Cu, Fe, Ni can promote reaction progress and reduce the apparent activation energy. ● Ni play better role in promoting WPCB pyrolysis reaction. Waste printed circuit boards (WPCBs) are generated increasingly recent years with the rapid replacement of electric and electronic products. Pyrolysis is considered to be a potential environmentally-friendly technology for recovering organic and metal resources from WPCBs. Thermogravimetric analysis and kinetic analysis of WPCBs were carried out in this study. It showed that the co-existing metals (Cu, Fe, Ni) in WPCBs have positive self-catalytic influence during the pyrolysis process. To illustrate their catalytic effects, the apparent activation energy was calculated by differential model. Contributions of different reactions during catalytic pyrolysis process was studied and the mechanism function was obtained by Šesták-Berggren model. The results showed that Cu, Fe, Ni can promote the reaction progress and reduce the apparent activation energy. Among the three metals, Ni plays better catalytic role than Cu, then Fe. This work provides theoretical base for understanding the three metals’ catalytic influence during the pyrolysis of non-metal powders in WPCBs.     

Packaging glass contained in the heavy residual fraction refused by Portuguese Mechanical and Biological Treatment plants

Mechanical and Biological Treatment (MBT) is an important strategy to manage Municipal Solid Waste (MSW) in Europe. The presence of recyclable materials on MSW depends on different factors such as inefficiencies in the Municipal Solid Waste collecting schemes and to the low level of citizenship environmental education. Among other products, MBT plants produce a residual fraction, named here as heavy residual fraction, that contains a significant amount of packaging glass which in Portugal is currently landfilled. This material is not recycled because it is heavily contaminated with other materials, preventing its processing in Material Recovery Facilities (MRF).In this paper the characterization, including particle size and composition, of the residual fraction of six Portuguese MBT plants is presented. The relevant variables that determine the heavy residual fraction characteristics were identified. It was observed that the MBTr particle size distribution is different and depends mainly on the place on the flowsheet where the MBTr exits the process, which is determined by the type of biological process and by the aperture of the last screen where the product passes through. The content in glass varies from 33 to 83%. These values are mainly related with the upstream glass sorting and with the efficiency of the recovery of the organic fraction which is the glass main contaminant. The second main contaminant is “stones”.The quantity of glass contained in this product in all the plants that will be in operation in Portugal in 2014 was estimated. The work shows that if all the 48,000 of glass could be recovered the Portuguese recycling rate would increase by 4.4%.     

Assessing and improving management practices when planning packaging waste collection systems

Packaging waste collection systems are responsible to collect, within a geographic area, three types of packaging materials (paper, glass and plastic/metal) that are disposed by the final consumer into special bins. Those systems are often characterized by having a network with multiple depots that act as transfer and sorting stations, and where the vehicle fleet is based. However, each depot is often managed independently and not as a part of a unique system. In this work, four current tactical/operational practices that contribute to the independent management of each depot are analysed. The change of such practices is investigated and their impact assessed on the total collection cost. A solution methodology based on mathematical formulations is developed to plan service areas, vehicle routes and vehicle schedules taking into account new alternative solutions in managing the system as a whole. Such methodology is applied to a real case study of a company responsible for the collection of the packaging waste in 7 municipalities in mainland Portugal. New service areas, collection routes and vehicle schedules are defined and significant savings are obtained in terms of the total distance travelled as well as in terms of the number of required vehicles, resulting in a decreasing of the total system cost.     

Techno-economic analysis and environmental impact assessment of energy recovery from Municipal Solid Waste (MSW) in Brazil

Due to the lack of appropriate policies in the last decades, 60% of Brazilian cities still dump their waste in non-regulated landfills (the remaining ones dump their trash in regulated landfills), which represent a serious environmental and social problem. The key objective of this study is to compare, from a techno-economic and environmental point of view, different alternatives to the energy recovery from the Municipal Solid Waste (MSW) generated in Brazilian cities. The environmental analysis was carried out using current data collected in Betim, a 450,000 inhabitants city that currently produces 200 tonnes of MSW/day. Four scenarios were designed, whose environmental behaviour were studied applying the Life Cycle Assessment (LCA) methodology, in accordance with the ISO 14040 and ISO 14044 standards. The results show the landfill systems as the worst waste management option and that a significant environmental savings is achieved when a wasted energy recovery is done. The best option, which presented the best performance based on considered indicators, is the direct combustion of waste as fuel for electricity generation. The study also includes a techno-economical evaluation of the options, using a developed computer simulation tool. The economic indicators of an MSW energy recovery project were calculated. The selected methodology allows to calculate the energy content of the MSW and the CH₄ generated by the landfill, the costs and incomes associated with the energy recovery, the sales of electricity and carbon credits from the Clean Development Mechanism (CDM). The studies were based on urban centres of 100,000, 500,000 and 1,000,000 inhabitants, using the MSW characteristics of the metropolitan region of Belo Horizonte. Two alternatives to recovering waste energy were analyzed: a landfill that used landfill biogas to generate electricity through generator modules and a Waste-to-Energy (WtE) facility also with electricity generation. The results show that power generation projects using landfill biogas in Brazil strongly depend on the existence of a market for emissions reduction credits. The WtE plant projects, due to its high installation, Operation and Maintenance (O&M) costs, are highly dependent on MSW treatment fees. And they still rely on an increase of three times the city taxes to become attractive.     

An examination of governance within extended producer responsibility policy regimes in North America

Extended producer responsibility seeks to integrate environmental impacts into the product lifecycle and achieve greater economic efficiencies in the management of products at end of life. For such integration to be actualized, however, producers may need to be accorded greater programmatic authority and flexibility than is often in some EPR policies that stipulate defined roles for other entities along the product chain. The proper allocation of responsibility among the parties and, in particular, the roles of the producers and local authorities remains a principal component of EPR policy construction. The analysis outlines four broad categories of financial and programmatic responsibility that currently reside within EPR programs in North America. The article concludes with recommendations for a research agenda to further define the governance characteristics that result in effective and efficient EPR programs.     

Reduction and utilization of coal mine waste rock in China: A case study in Tiefa coalfield

In China, coal mine waste rock (CMWR) produced during coal mining and processing is still increasing significantly as a result of coal production which has huge environmental impact. CMWR reduction and utilization is a major issue for coal enterprises and government to reduce the surface footprint and the public environmental impact. Tiefa coalfield, an old coalfield with 60 years of coal exploitation, was selected as a case to study the methods to minimize the environmental impacts of CMWR piles in a short period. We argue that a systematic design on CMWR utilization is needed on the basis of a usage evaluation which takes consideration of CMWR source, compositions, and proximate analysis. Mine design is crucial and the base for reducing the CMWR generation at the headstream. Placing roadway into coal seam rather than rock, panel optimization, and parametric analysis for mining technique were conducted in Tiefa coalfield. A promising technology of CMWR backfill under the ground was employed with a resultant increase of coal recovery rate. The surface CMWR recycling depends on brick making, electricity generating, and rehabilitation of subsided land. The practice of the presented methods indicates that the CMWR piles on Tiefa coalfield may disappear in 3 years, which could significantly reduce the environmental impacts of CMWR dumps. The technologies conducted in Tiefa coalfield developed a model of CMWR reduction and utilization for Chinese coal mines.     

Design of a European agrochemical plastic packaging waste management scheme—Pilot implementation in Greece

Mismanagement of Agrochemicals Plastic Packaging Waste (APPW) constitutes a major environmental problem, resulting in the pollution of soil, air and water resources and compromising the agricultural products safety, the protection of the environment and the public health. Systems for the management of APPW have been established in some European countries and they are operational for several years now. However, these schemes are incompatible while their operational conditions and technical criteria could be improved. In many countries no schemes exist yet for the management of APPW with serious negative consequences for the environment and public health. In response to these problems the European project AgroChePack has developed an environmental friendly, economically viable European APPW management scheme by transferring know-how from existing schemes, designing a new integrated APPW management scheme and testing it through pilot trials in five countries. This work presents the basic design principles established by AgroChePack by identifying problems and bottlenecks faced by existing schemes in Europe, by developing an integrated APPW scheme and by implementing, evaluating and optimising this scheme through pilot trials in Greece.     

Measuring the impact of prefabrication on construction waste reduction: An empirical study in China

Prefabrication has been widely regarded as a sustainable construction method in terms of its impact on environmental protection. One important aspect of this perspective is the influence of prefabrication on construction waste reduction and the subsequent waste handling activities, including waste sorting, reuse, recycle, and disposal. Nevertheless, it would appear that existing research with regard to this topic has failed to take into account its innate dynamic character of the process of construction waste minimization; integrating all essential waste handling activities has never been achieved thus far. This paper proposes a dynamic model for quantitatively evaluating the possible impacts arising from the application of prefabrication technology on construction waste reduction and the subsequent waste handling activities. The resulting model was validated based on an actual building project in Shenzhen, China.The simulation results of the design scenarios indicate that the policy on providing subsidy for each square meter of the prefabrication adopted in the construction would have more significant effect on promoting the use of prefabrication and improving the performance of construction waste reduction compared to the increase of income tax benefits. The results also show that (1) interaction exists among different management measures, and (2) the combined effect of multiple policies is larger than the simple sum of their individual impacts, indicating the need for comprehensive consideration on the combined effect of these potential polices. This paper demonstrates the potential benefits of using a system dynamics approach in understanding the behavior of real-world processes. The developed model not only serves as a practical tool for assessing the impact of off-site prefabrication on construction waste reduction and the corresponding waste handling activities, but also help provide a valuable reference to policy makers through the comparison of simulation results generated under various scenarios such that the best policy mix can be identified prior to production.     

Environmental sustainability assessment of food waste valorization options

Food waste can be valorized through different technologies, such as anaerobic digestion, incineration, and animal feed production. In this study we analyzed the environmental performance of two food waste valorization scenarios from a company of the retail sector in Belgium, through exergy analysis, exergetic life cycle assessment (ELCA), and a traditional life cycle assessment (LCA). In scenario 1 all food waste was considered to be valorized in an anaerobic digestion (producing electricity, heat, digestate and sorting the packaging material to be used as fuel for cement industry), while in scenario 2 a bread fraction was valorized to produce animal feed and a non-bread fraction was valorized in an anaerobic digestion (producing the same products on scenario 1, but in lower amounts). Scenario 2 was 10% more efficient than scenario 1 in the exergy analysis. For the ELCA and the single score LCA, scenario 2 presented lower environmental impacts than scenario 1 (32% and 26% lower, respectively). These results were mainly due to the avoided products from traditional supply chain (animal feed produced from agricultural products) and lower exergy loss at the feed production plant. Nevertheless, the high dry matter content of the bread waste played an important role on these results, therefore it should be pointed out that valorizing food waste to animal feed seems to be a better option only for the fractions of food waste with low water content (as bread waste).