Waste Ends Research Articles

Valorisation of Aggregate-Washing Sludges in Innovative Applications in Construction.

The valorisation of sludges from aggregate production into construction materials is required for full circularity in mining waste management. This study explores valorisation pathways, relevant regulatory frameworks, and End-of-Waste (EoW) criteria for specific settings in Spain and Norway. The explored valorisation routes involved the production of filler, supplementary cementitious materials (SCMs), and lightweight aggregates (LWAs) for the production of cement-based products, and precursors for 3D printed construction material. The sludge from Norway revealed a non-polluted stream and a stream contaminated with organic phases and clays. Sludge-based filler proved suitable in concrete production with contents of up to 40% of total binder, providing adequate consistency and cohesion. However, clays in the sludge increased the demand for water and superplasticizer. Clay contents were still insufficient for the applications as SCMs, as the calcined sludge demonstrated limited reactivity. The application to produce LWAs was promising, but further microstructure optimization is still required. The clay content was also relevant for the sludge from the site in Spain, as it provided 3D printing mixes with good plasticity. The dosage optimization still required the addition of enzymes, limestone, and natural fibres to improve cohesion, workability, and resistance to the cracking of the 3D printing mix.

THE TACIT END-OF-WASTE STATUS IS de facto USED IN THE EU AND CRUCIAL FOR THE CIRCULAR ECONOMY

For a well-functioning circular economy, recycled materials with a specific purpose, that have a market, and meet the legal requirements for both products and the environment should have an end-of-waste (EoW) status. However, at the EU level, EoW has only been established for certain metals and cullet glass, and implementation at the national level has slowed down. One potential solution is tacit EoW, supported by articles 6(1) and 6(4) of the Waste Framework Directive (WFD), which place responsibility on economy operators with possible oversight by authorities. This discussion paper examines the status of various waste streams in the EU and illustrates that tacit EoW is already widely used in regulation and waste management practices. This includes: - Reuse of waste as a product after preparation (level 2 of the waste hierarchy); - Recycling of materials (level 3 of the waste hierarchy) to produce new products; - Recycling in environmental applications, such as fertilisers, soil conditioners, and growing substrates, as well as backfilling operations; - Energy production from various biomass and wood waste categories. Granting tacit EoW status consistent with level 3 of the waste hierarchy to other materials processed by certified industrial facilities would benefit the circular economy. A first group consists of materials recycled into products that do not come into contact with the environment, which could benefit from immediate tacit EoW, since the four EoW conditions are met. Ten wastes of this group are ranked for priority EoW by the Joint Research Center of the EU.

Sustainable approaches in concrete production: An in-depth review of waste foundry sand utilization and environmental considerations.

This review critically evaluates the potential of Waste Foundry Sand (WFS) as a substitute for fine aggregate in concrete, conducting a comparative analysis of its physical and chemical properties against those of natural sand. The study synthesizes findings from various research experiments to determine concrete's most effective WFS replacement percentage. It compiles and analyzes data on how different WFS ratios affect concrete's mechanical properties, including modulus of elasticity and compressive strength. The review also consolidates research on the impact of WFS on concrete's workability, density, and flowability. A key finding is that WFS, categorized as a non-hazardous waste, possesses a diverse particle size distribution, rendering it suitable for recycling in various industrial applications.The study identifies that a 20%-30% replacement of WFS in concrete significantly improves properties such as voids, specific gravity, and density. However, it is essential to note that exceeding a 30% WFS replacement can result in increased carbonation depth and decreased resistance, primarily due to sulfur trioxide (SO3). Further observations indicate that incorporating higher levels of WFS in self-compacting concrete reduces its flowability and increases water permeability. Moreover, the review highlights the regulatory and classification challenges associated with using WFS, particularly its classification as waste, which hampers its widespread adoption in construction. In conclusion, the study recommends implementing End-of-Waste (EoW) regulations to facilitate sustainable recycling and environmental protection. Additionally, it includes a bibliometric analysis of foundry sand research spanning from 1971 to 2020, providing a comprehensive summary of the field's historical and recent developments.

End-of-Waste Criteria of the Bauxite Red Mud

The main objective of this document is to present the End-of-Waste (EoW) criteria for the bauxite red mud. EoW criteria are based on the different EoW approaches and criteria existing around the European Union (EU), especially for Construction and Demolition Waste (CDW) and the results obtained in the CINDERELA project (EU contr. No. 776751). This EoW criteria protocol could facilitate the recycling process of bauxite red mud thus guiding Republic of Montenegro to implement EoW criteria for this waste, which is landfilled in huge quantity (8 million tonnes) near Podgorica. This document will define the product status, its technical quality and applicability as well as its environmental and human health issues.

The validation of converting pyrite ash-contaminated soil into End-of-Waste by the High-Performance Solidification/Stabilization process application.

One of the major challenges to establishing more sustainable management strategies than landfill disposal of metals-contaminated soils is the lack of End-of-Waste (EoW) criteria defined at the European and national levels. Another limitation stems from the scarcity of information on industrial-scale applications of treatment technologies able to obtain safe and reusable materials from such contaminated waste. In this context, the High-Performance Solidification/Stabilization process was applied for the full-scale remediation of pyrite ash-contaminated soil (ca. 24 000 m3 ), and a dedicated sampling and analytical protocol was developed and implemented to verify if the treated material obtained complied with the general EoW criteria established by article 6 of the Waste Framework Directive 2008/98/EC. The results of the leaching, ecotoxicological, and mechanical tests carried out on representative samples of the treated soil showed that this material (ca. 19 000 m3 ) could be classified as EoW and thus was deemed reusable both in-situ as filler for the excavation and ex-situ as road construction material. These results improve the knowledge of the performance of a state-of-the-art technique for the treatment of metals-contaminated soil. Furthermore, the developed monitoring plan can support future assessments on the compliance of materials obtained from contaminated soil with the general EoW criteria. Integr Environ Assess Manag 2023;19:961-969. © 2022 SETAC.

Critical issues hindering a widespread construction and demolition waste (CDW) recycling practice in EU countries and actions to undertake: The stakeholder's perspective

Construction and demolition waste (CDW) reuse and recycling represents a key point to enhance resource efficiency in construction sector and to reduce the huge volumes of extracted materials, energy consumption and waste production, which make this sector the largest resource consuming and waste producing one. Even if several alternatives for raw materials substitution have been widely investigated from a technical and economic point, several critical issues hinder a wide substitution rate of virgin raw materials with CDW valorised streams slowing down the circular economy transition. The aim of this research was to individuate and discuss these issues hindering a widespread CDW recycling practice in order to individuate actions to undertake, that can support policies and action plans. The investigation was conducted through desk research and a survey, through the administration of questionnaires and more focused guided interviews. Difficulties and barriers have been analysed and suggestions to improve waste recycling and reuse have been proposed. The state of implementation of policies, actions and best practices such as Green Public Procurement (GPP); b) End of Waste (EoW) criteria; c) pre-demolition audit; d) selective demolition; e) landfill tax; f) tax on raw material extraction; g) traceability system; h) take-back centres, have been examined and discussed. Finally, ideas and suggestions aimed at directing the correct implementation of policies, initiatives and action plans, starting from the successful experiences of some countries that could be effectively transferred in other ones and, trying to take advantage of the difficulties encountered in the implementation process, have been proposed.

When Physical Chemistry Meets Circular Economy to Solve Environmental Issues: How the ReScA Project Aims at Using Waste Pyrolysis Products to Improve and Rejuvenate Bitumens

Urban waste management is a hard task: more than 30% of the world’s total production of Municipal Solid Wastes (MSW) is not adequately handled, with landfilling remaining as a common practice. Another source of wastes is the road pavement industry: with a service life of about 10–15 years, asphalts become stiff, susceptible to cracks, and therefore no longer adapted for road paving, so they become wastes. To simultaneously solve these problems, a circular economy-based approach is proposed by the ReScA project, suggesting the use of pyrolysis to treat MSW (or its fractions as Refuse Derived Fuels, RDFs), whose residues (oil and char) can be used as added-value ingredients for the asphalt cycle. Char can be used to prepare better performing and durable asphalts, and oil can be used to regenerate exhaust asphalts, avoiding their landfilling. The proposed approach provides a different and more useful pathway in the end-of-waste (EoW) cycle of urban wastes. This proof of concept is suggested by the following two observations: (i) char is made up by carbonaceous particles highly compatible with the organic nature of bitumens, so its addition can reinforce the overall bitumen structure, increasing its mechanical properties and slowing down the molecular kinetics of its aging process; (ii) oil is rich in hydrocarbons, so it can enrich the poor fraction of the maltene phase in exhaust asphalts. These hypotheses have been proved by testing the residues derived from the pyrolysis of RDFs for the improvement of mechanical characteristics of a representative bitumen sample and its regeneration after aging. The proposed approach is suggested by the physico-chemical study of the materials involved, and aims to show how the chemical knowledge of complex systems, like bituminous materials, can help in solving environmental issues. We hope that this approach will be considered as a model method for the future.

Eow criteria for waste-derived aggregates

Waste-derived aggregates are being considered as possible candidates for development of End-of-Waste (EoW) criteria at European Union (EU) level in accordance with Article 6 (1) of the EU Waste Framework Directive (2008/98/EC) as a means of increasing the recovery of resources from waste. If a waste-derived aggregate achieves EoW status, it will become a (construction) product and hence be regulated by the Construction Products Regulation (CPR) which means that in most EU Member States there will be no applicable environmental protection regulation. It is therefore important that the criteria a waste-derived aggregate must fulfil to achieve and maintain EoW status ensure sufficient protection of the environment and human health. It is shown that EoW criteria that do not include restrictions on the conditions of the use of waste-derived aggregates for specific construction purposes will result in leaching limit values that are so stringent that very few, if any, waste-derived aggregates can meet them. It is therefore proposed to impose restrictions and conditions on the use as part of possible future EoW criteria for waste-derived aggregates, and a step-wise methodology for development of more realistic leaching limit values for EoWis outlined. The methodology incorporates the mitigating effects of various measures that reduce the potential environmental impact of construction applications with waste-derived aggregates. Recommendations are also made of the practical testing and documentation procedures for aggregates with EoW status within the framework of the CPR.

Gravity packaging final waste recovery based on gravity separation and chemical imaging control

Plastic polymers are characterized by a high calorific value. Post-consumer plastic waste can be thus considered, in many cases, as a typical secondary solid fuels according to the European Commission directive on End of Waste (EoW). In Europe the practice of incineration is considered one of the solutions for waste disposal waste, for energy recovery and, as a consequence, for the reduction of waste sent to landfill. A full characterization of these products represents the first step to profitably and correctly utilize them. Several techniques have been investigated in this paper in order to separate and characterize post-consumer plastic packaging waste fulfilling the previous goals, that is: gravity separation (i.e. Reflux Classifier), FT-IR spectroscopy, NIR HyperSpectralImaging (HSI) based techniques and calorimetric test. The study demonstrated as the proposed separation technique and the HyperSpectral NIR Imaging approach allow to separate and recognize the different polymers (i.e. PolyVinyl Chloride (PVC), PolyStyrene (PS), PolyEthylene (PE), PoliEtilene Tereftalato (PET), PolyPropylene (PP)) in order to maximize the removal of the PVC fraction from plastic waste and to perform the full quality control of the resulting products, can be profitably utilized to set up analytical/control strategies finalized to obtain a low content of PVC in the final Solid Recovered Fuel (SRF), thus enhancing SRF quality, increasing its value and reducing the “final waste".

Standardization of Solid Recovered Fuels through Gravity Separation and Chemical Based Imaging Techniques

The European politics is addressed, in their last years, more and more towards the abolition of landfills and oriented to verify the possibility to improve their recovery through actions of recycling, composting and energy production. Currently the European Directive 2008/98/EC, through the principle of End of Waste (EoW), is driving the utilization of new methods of waste processing in order to transform them it into a new “renewable” product. The post-consumer plastics resulting from packaging account for about 60% of total plastics waste (i.e. 23 million tons) produced in Europe. The high quality Solid Recovered Fuel (SRF) is a partial solution to the problem of waste and landfill management, becoming integral and essential in the closure of the waste cycle, representing one of virtuous processes for the treatment and recovery of waste. The application of recycling strategies, finalised to polymers recovery, can thus represent an important opportunity to reduce: i) not renewable raw materials utilization (i.e. oil), ii) carbon dioxide emissions and iii) the amount of plastic waste disposed-off. Aim of this work is to study the possibility offered by the integrated utilization of Chemical Imaging (CI) based techniques in order to obtain a good quality SRF characterized by a low content of PVC derived packaging to be used for the production of thermal energy. Packaging “final waste”, in fact, is usually characterized by the presence of PolyVinyl Chloride (PVC). Therefore the association of a specific gravity separation architecture with the CI based sensing units, could strongly improve the quality of “final waste” fraction as resulting from classical recycling processes based on milling, classification and density separation. The presence of PVC, in fact, has a negative influence on the combustion and heat recovery of these products due to the production of dioxins and furans. The utilization of the proposed combined approach (i.e. gravity and CI based) could contribute to obtain a SRF characterized by a very low PVC content, thus allowing to certify SRF according to UNI EN 15359:2011 and to correctly utilise it for thermal energy production.

EoW Criteria for Waste-Derived Aggregates

Waste-derived aggregates are being considered as possible candidates for development of End-of-Waste (EoW) criteria at European Union (EU) level in accordance with Article 6 (1) of the EU Waste Framework Directive (2008/98/EC) as a means of increasing the recovery of resources from waste. If a waste-derived aggregate achieves EoW status, it will become a (construction) product and hence be regulated by the Construction Products Regulation (CPR) which means that in most EU Member States there will be no applicable environmental protection regulation. It is therefore important that the criteria a waste-derived aggregate must fulfil to achieve and maintain EoW status ensure sufficient protection of the environment and human health. It is shown that EoW criteria that do not include restrictions on the conditions of the use of waste-derived aggregates for specific construction purposes will result in leaching limit values that are so stringent that very few, if any, waste-derived aggregates can meet them. It is therefore proposed to impose restrictions and conditions on the use as part of possible future EoW criteria for waste-derived aggregates, and a step-wise methodology for development of more realistic leaching limit values for EoW is outlined. The methodology incorporates the mitigating effects of various measures that reduce the potential environmental impact of construction applications with waste-derived aggregates. Recommendations are also made of the practical testing and documentation procedures for aggregates with EoW status within the framework of the CPR.

The challenge to overcome institutional barriers in the development of industrial residue based novel symbiosis products – Experiences from Finnish process industry

The sustainable utilisation of natural resources requires a new focus on optimal material cycles and material efficiency. Recycling and sustainable industrial development through improved process design are therefore key in this context. In this study, we assessed the potential barriers within the Finnish legal framework regarding the development of novel residue-based industrial symbiosis products. A review is also made of the UK based Waste and Resources Action Programme (WRAP) and Finnish MOTIVA initiatives both of which aim at promoting sustainable and efficient use of materials focussing on the examination of End of Waste (EoW) approaches and quality protocols that guide residue recovery. The research approach was based on both legal review and analysis of relevant policy instruments. The research material includes interviews of actors in both operations and environmental management in various process industry companies in Finland. An industrial symbiosis case study is presented based on previous research and close collaboration between the metals and forest products process industry. The main research question is “does EU policy and the legal framework at the national level create barriers to the development of innovative residue based symbiosis products despite the fact that achievement of the stated goals of ‘recycling society’ and ‘sustainable industry’ require sustainable use of natural resources and high level of material efficiency such as enhanced waste utilisation and prevention?” The results suggest that an innovative approach to environmental permitting and a comprehensive approach to recycling, encompassing new quality and environmental compliance criteria for certain recycled materials, should receive more focus in future decision-making. Material and energy efficiency, as well as life-cycle and systems thinking are all found to be essential elements of this new approach to inter-industrial residues streams. We find that the institutional status of one of our case study products in particular (a fertiliser product, based on multiple residue stream derived raw materials), should be clarified. This paper focuses on Finnish domestic framework issues. It is continuation of the article Watkins et al. (2013)Overcoming institutional barriers in the development of novel process industry residue based novel symbiosis products – case study at the EU level. However, it can be read as an individual research paper.