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ERE4.2

EDI
Circular economy and resource recovery: from waste to raw material

Material recovery is critical to recoup as much as of the waste economic and ecological value (Thierry et al., 1995). In the Circular Economy, this is of the utmost importance to close material loops and re-design production and consumption patterns in a more restorative and regenerative fashion (Morseletto, 2020). Indeed, different types and levels of material recovery can soothe the pressure on raw material extraction and hopefully reduce the ultimate quantities of waste.
Material recovery plays a leading role in the current quest for circularity. Therefore, we are interested in hosting studies looking at the circular use of wastes for material recovery. We welcome and encourage interdisciplinary approaches to the topic. Potential research issues include but are not limited to the following:

1. Resource extraction/recovery from wastes;
2. Metals and Rare Earth Elements (REE) extraction and recovery techniques;
3. Reuse of waste materials in construction;
4. Techniques that perform resource recovery;
5. Drawbacks of and barriers to material recovery;
6. Digital technologies for material recovery;
7. Material recovery for Industrial Symbiosis;
8. Business models and practices for Material Recovery.

Convener: Ana Teresa Lima | Co-conveners: Pierluigi Zerbino, Davide Aloini, Lisbeth M. Ottosen, Alexandra EscobarECSECS
Presentations
| Thu, 26 May, 10:20–11:44 (CEST), 13:20–13:55 (CEST)
 
Room 0.31/32

Thu, 26 May, 10:20–11:50

Chairpersons: Ana Teresa Lima, Pierluigi Zerbino

10:20–10:27
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EGU22-2411
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ECS
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Virtual presentation
Davide Bernasconi et al.

Municipal solid waste incineration fly ash (MSWI-FA) is one of the solid by-products of MSWI treatment, accounting for about 1–3% of the total incinerated waste. FA forms in the plant purification system and bears important amount of heavy metals and salt (chloride and sulphate), therefore it is considered as hazardous waste (Bernasconi et al, 2022). For this reason, FA is required to undergo stabilization/inertization treatment (one of the most common is water washing), before being landfilled or used as secondary/supplementary raw materials. In this latter case, many studies have evaluated the incorporation of FA into alkali silicate-based geopolymer. This material is obtained by the reaction between an aluminosilicate source (metakaolin, MTK) and alkali hydroxide (NaOH, KOH), to obtain polymer-like condensation product (Wang et al, 2019). This material is characterized by higher durability and greenness with respect to the conventional Portland cement (OPC), thus gaining interest recently as a promising partial substitute to OPC. On the other hand, much less attention has been focused on acid-based geopolymer, in which the alkali hydroxide is substituted by phosphoric acid, thus producing an Al-O-P/Si-O-P polymeric matrix (Wang et al, 2019). This material has displayed better performance than the traditional alkali-silicate geopolymer, in terms of corrosion resistance (Wagh et al, 2011), thermal stability (Celerier et al, 2019) and mechanical strength. However, there are also some drawbacks, mainly related to the expensive cost of the starting materials, since MTK is obtained by high-temperature (750°C) calcination of kaolinite. The introduction of FA would be economically beneficial both by reducing the amount of MTK needed and providing a destination for a waste residue which otherwise would require important management costs.

In this work, (previously washed) FA partial replacement of MTK has been tested in the phosphate-based geopolymer formulation, up to 50 wt%. Different synthesis conditions have been evaluated, in terms of Al/P molar ratio, liquid-to-solid ratio and curing temperature. The resulting reaction products have been investigated by a combined analytical approach, involving spectroscopies (ATR-FTIR and Solid-state NMR) and powder X-ray diffraction techniques, while their morphology was inquired by SEM-EDS analysis. Moreover, compressive strength tests have been employed to evaluate the mechanical properties, which demonstrated the good performances of FA blended phosphate-based geopolymers, with compressive strength values over 30 MPa.

 

Reference

  • D. Bernasconi, C. Caviglia, E. Destefanis, A. Agostino, R. Boero, N. Marinoni, C. Bonadiman, A. Pavese. Influence of speciation distribution and particle size on heavy metal leaching from MSWI fly ash, Waste Management, 138 (2022), 318-327.
  • Y. Wang, Y. Alrefaei, J. Dai. Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review, Frontiers in Materials, 6 (2019), 106.
  • A.S. Wagh. Phosphate geopolymers, Ceramic Engineering and Science Proceeding, 32, 10 (2011), 91-103.
  • H. Celerier, J. Jouin, A. Gharzouni, V. Mathivet, I. Sobrados, N. Tessier-Doyen, S. Rossignol. Relation between working properties and structural properties from 27Al, 29Si and 31P NMR and XRD of acid-based geopolymers from 25 to 1000 °C, Materials Chemistry and Physics, 228 (2019), 293-302.

How to cite: Bernasconi, D., Viani, A., Mácová, P., Zárybnická, L., Caviglia, C., Destefanis, E., Bordignon, S., Gobetto, R., and Pavese, A.: MSWI fly ash incorporation into acid-based geopolymer: reactivity and performance impact, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2411, https://doi.org/10.5194/egusphere-egu22-2411, 2022.

10:27–10:34
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EGU22-3176
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On-site presentation
Hamdy El Desouky

The growth of the world population pressures for an increasing demand for the extraction of the Earth's non-renewable mineral resources, which are essential for modern living. The heavy mining operations associated with this extraction have several negative environmental and societal impacts, including the emission of greenhouse gases and the production of large volumes of solid waste. Green mining aims to adapt the mining operations to reduce the negative impacts, while maintaining the interests of stakeholders.

Basalt is a mafic volcanic rock that is widely available in the Earth's surface and often occurs in a variety of ore deposit systems. Traditionally, basalt is used in various ornamentation and construction purposes. However, recently, novel agricultural, environmental and even industrial applications of basalt emerged. When basalt is crushed to a reasonable size (preferably ≤250 µm) and applied to soils in an adequate application rate (5 to 20 t ha-1), it acts as a natural fertilizer. Basalt is predominantly composed of Ca-rich plagioclase, pyroxene and olivine. These rock-forming minerals have a fast weathering rate compared to other silicate minerals. When they come in contact with water and CO2, from the atmosphere, they dissolve releasing a broad spectrum of macronutrients, micronutrients and beneficial elements (e.g., Si, Fe, Ca, Mg, Mn, Na, K, P, S, Ti, V, Cu, Zn, Co & REEs), which are important for plant growth. During this natural enhanced weathering process, an adequate amount of CO2 is sequestered from the atmosphere.

Here, a novel green mining technique is proposed for ore deposits, hosted in or associated with basalt. This technique proposes the separation of the barren or very weakly mineralized basaltic bodies from the remaining solid waste. These bodies should be further crushed and distributed over local farmlands and forests. Crushed basalt will act as a slow release, natural fertilizer, which will rejuvenate weathered soils, boost soil fertility, neutralize soil acidity and enhance plant growth. This will increase the green cover and yield and will reduce the farming costs, which will have positive socio-economic impacts on the local community. More importantly, this green mining technique will reduce the amount of solid mining waste and will sequester a considerable amount of CO2 from the atmosphere, during the enhanced weathering process, which could compensate for the CO2 emitted from the mining operations. Although the process appears straightforward and of high benefit for the environment, the mining sector and the local society, a special monitoring program should be initiated to assess the heavy metal content of the distributed basalt dust to avoid contaminating soils, especially in the case of high application rates (>5 t ha-1).

This ongoing research aims to develop sustainable green mining programs to recycle and reuse the solid mine waste for CO2 sequestration and for the development of natural, slow release, low cost, eco-friendly fertilizers.

How to cite: El Desouky, H.: Role of Basalt in Green Mining , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3176, https://doi.org/10.5194/egusphere-egu22-3176, 2022.

10:34–10:41
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EGU22-3852
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ECS
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On-site presentation
Sophie van Roosmale et al.

Geopolymers are an interesting material because they are inorganic and non-toxic, they are inexpensive because the raw materials are easy to obtain, and they also have high strength and are able to process and adjust. These properties make them an innovative alternative to restoration mortars, which carry out current restoration treatments of stone heritage, but which often cause more damage because they are not fully compatible with the original.

Geopolymers are stone-like materials placed between binders, such as cements and ceramics. Different types of geopolymers exist, depending on the raw materials and the system through which they are activated. In this research we focus on geopolymers with a base of metakaolin. Metakaolin based geopolymers improve the properties of the end product compared to geopolymers based on fly-ash and ground granulated blast furnace slag. For curing the geopolymer, certain requirements have been set that take into account the application of the geopolymer in the restoration sector in the future, like curing by room temperature and ambient relative humidity in less than 48 hours. A set of reactivity tests have been performed to determine the appropriate activator and to optimize their ideal molarity. These tests shows that calcium hydroxide give the best results in forming a matrix of geopolymer.

In the next phase of the research, the compatibility between the geopolymer and porous sedimentary building stones will be investigated. The properties that are important for technical compatibility include: porosity, pore size distribution, capillary water absorption, frost resistance, structure, texture, compressive and bending strength. Samples are made with standardized aggregates of marl flour (porous calcium carbonate flour), limestone flour (non-porous calcium carbonate flour) and relatively pure sand with various grain size distribution to evaluate the compatibility and to investigate the effects on reactivity. It is critical this test phase is carried out with pure products, so that any contamination cannot affect the results. In the following stage it is then possible to experiment with the effect of degraded and contaminated original material as aggregate.

How to cite: van Roosmale, S., De Kock, T., and Blom, J.: Investigation of custom-made metakaolin-based geopolymers for stone conservation: preliminary results on activation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3852, https://doi.org/10.5194/egusphere-egu22-3852, 2022.

10:41–10:48
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EGU22-4272
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Virtual presentation
Caterina Caviglia et al.

This work is focused on the possible reutilization of municipal solid waste incinerator (MSWI) fly ash as a metakaolin replacement in the acid-based geopolymer. This type of geopolymer, obtained by the reaction between an aluminosilicate source (metakaolin) and phosphoric acid to form an Al-O-P/Si-O-P matrix (Wang et al, 2019), have displayed better performance than the traditional alkali-silicate geopolymer, in terms of corrosion resistance (Wagh et al, 2011), thermal stability and mechanical strength (Celerier et al, 2019). The replacement of up to 30 % wt has proved to not significantly alter the remarkable performance of the material, obtaining compressive strength values higher than 30 MPa. However, since fly ash contains dangerous substances as chlorides, sulfates, and heavy metals, which must be stabilized, it is important to evaluate the leching stability of the final materials.

Therefore, test cube blocks of 1x1x1 cm size, containing 10, 20 and 30 % wt of previously washed fly ash replacement with respect to metakaolin are prepared, with Al/P molar ratio of 1, liquid-to-solid ratio raging from 0.95-1 and 3 days at 60°C as curing temperature. 

Leaching tests, according to the European standards EN-12457 (2002), using deionized water at a ratio liquid to solid of 10, are applied to geopolymers blocks to evaluate the concentration of salts and heavy metals that usually exceeds the law threshold in the raw fly ash. Leachates are analyzed by ionic chromatography and ICP-MS: the results show that the concentrations of chlorides are under the legislation limits provided for not dangerous waste, as well as sulfates and fluorides; relatively to heavy metals Zn, Pb, Cd exceed the concentrations limits. Further tests and analyses are carried out to evaluate the impact of synthesis parameters on the leaching stability of these materials.

 

Reference

 

  • Wang, Y. Alrefaei, J. Dai. Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review, Frontiers in Materials, 6 (2019), 106.

 

A.S. Wagh. Phosphate geopolymers, Ceramic Engineering and Science Proceeding, 32, 10 (2011), 91-103.

 

  • Celerier, J. Jouin, A. Gharzouni, V. Mathivet, I. Sobrados, N. Tessier-Doyen, S. Rossignol. Relation between working properties and structural properties from 27Al, 29Si and 31P NMR and XRD of acid-based geopolymers from 25 to 1000 °C, Materials Chemistry and Physics, 228 (2019), 293-302.

How to cite: Caviglia, C., Destefanis, E., Bernasconi, D., Pastero, L., Pavese, A., Viani, A., Mácová, P., and Zárybnická, L.: Environmental suitability of MSWI fly ash geopolymers: evaluation by leaching tests , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4272, https://doi.org/10.5194/egusphere-egu22-4272, 2022.

10:48–10:55
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EGU22-4563
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ECS
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Virtual presentation
Giulio Galamini et al.

Both nitrogen (N) and phosphorous (P) are essential for life and their supply sustain the global population growth, thus, the question about “how correctly manage nutrient-rich wastewaters?” is a primary issue for many countries. The storage and the subsequent thoughtless use of these materials, as breeding farm and biogas plants wastewaters, has enormous impacts on the environment, causing eutrophication of water bodies and greenhouse gas emissions. The development of low-cost, low environmental impact and high yield treatment technologies is thus necessary to incentivize the circularity of resources, promoting their reuse and encouraging recycling in agri-food systems.

The recovery of N and P by struvite precipitation (MgNH4PO4·6H2O) is a promising strategy, but these technologies are in general too expensive, energy-demanding, or they alter the treated wastewaters, making them not suitable for agricultural purposes unless additional treatments are carried out.

This work investigates an innovative wastewater treatment processes that foresee the use of a natural chabazite-rich zeolitite (rock containing more than 50 % of zeolite minerals) in combination with struvite chemical precipitation. The adsorption batch (phase 1) is intended to improve the NH4+/Mg2+ and NH4+/PO43- molar ratios, to enhance struvite yield (phase 2) with fewer amounts of reagents required, thus to improve both the efficiency and the cost-effectiveness of struvite production. For the 1st phase, both natural zeolitite (NZT) and the K+-enriched (KZT) zeolitite were tested. KZT was intended to counteract any possible interference for struvite precipitation, which could instead happen with NZT due to the input of Ca2+ ions in solution.

In the 2nd phase (struvite precipitation), 2 different Mg:NH4:PO4 molar ratios were tested, in particular a condition of NH4+ excess (MR1) and a condition with Mg2+ in excess (MR2).

Treatments in which NZT (NZT-S) and KZT (KZT-S) were added prior to struvite precipitation were compared to a conventional struvite precipitation method without the use of zeolitites (CNTR).

NZT-S_MR1 was found to be the most feasible strategy because of the highest NH4+-N removal efficiency, highest struvite precipitation efficiency (less waste of reagents), and less unwanted alterations of the treated wastewater. The precipitate obtained was 89.9 mass % composed of struvite with 3.5 % N, poor in hazardous heavy metals.

The NH4+-N removal efficiency was in order: NZT-S > KZT-S > CNTR, with the highest reduction of 84.8 % recorded by NZT-S_MR1 and the lowest recorded by the CNTR (67.2 and 75.0 % for MR1 and MR2 respectively).

The addition of a “zeolite phase” in struvite precipitation process thus represents i) a valuable method for improving the efficiency of struvite production ii) a method for saving chemical reagents in struvite production and iii) an efficient way to recover and recycling N in agriculture.

How to cite: Galamini, G., Ferretti, G., Medoro, V., Eftekhari, N., Faccini, B., and Coltorti, M.: The use of a natural chabazite-rich zeolitic tuff improved struvite precipitation and nutrient recovery from anaerobically digested wastewater, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4563, https://doi.org/10.5194/egusphere-egu22-4563, 2022.

10:55–11:02
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EGU22-4819
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ECS
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Virtual presentation
Katerine Elizabeth Ponce Ochoa et al.

Current population growth has generated an increase in the food and culinary industry production, which has resulted in an increase in the consumption of vegetable oils on large restaurant chains as well as on small food stalls. This situation justifies the increasing generation of large amounts of residual vegetable oils that lead to serious problems in their purification due to their slow degradation.

This research is focused in the city of Cuenca (Ecuador) where a program for the collection of residual vegetable oils run by the company ETAPA – EP is being developed. It must be taken into account that this program has been implemented for a selected number of large restaurants but does not include other waste production sources, such as small restaurants, food carts and fast-food stalls that are usually quite frequent in the city and do not integrate an adequate management control over this type of residual waste.

This work explores for the first time the possibility of turning residual vegetable oils management into a source of income and job positions while protecting the environment. In order to carry out this study, information about the location of waste generation points and the amount of residual oil has been collected and processed using GIS tools.

How to cite: Ponce Ochoa, K. E., Rodrigo-Clavero, M. E., and Rodrigo-Ilarri, J.: Analysis of the production of residual vegetable oils from the food and culinary industry in the city of Cuenca (Ecuador) using GIS tools, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4819, https://doi.org/10.5194/egusphere-egu22-4819, 2022.

11:02–11:09
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EGU22-4981
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ECS
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Virtual presentation
Vergani Fabrizio and the Progetto Dear

Asbestos minerals, namely chrysotile and fibrous amphiboles, have long been used as components in construction materials, as for instance the cement-asbestos (CA) slates used in roofing, exploiting their capability to increase mechanical strength. As well known, asbestos minerals have been recognised toxic and banned almost worldwide. Current remediation approaches include confinement, encapsulation and removal (followed by disposal in controlled landfills). A more attractive solution, strongly recommended by the EC, is detoxification and reuse, in a perspective of circular economy.

In the present contribution we explored the possibility to reuse thermally treated and deactivated CA powder (a mixture of glass and Ca-Mg silicates typical of cement – details in Vergani et al. 2021) as filler in: i) flour-elastomers (FKM type, characterized by high resistance to oil and temperature) and bi-component epoxy resins (bisphenol-A, epichlorohydrine based resins) used in flooring. For each application, different formulations (different proportions of conventional raw materials and deactivated CA powder) have been prepared and tested according to conventional quality test protocols and SEM micro-textural observations.

As regard the reuse in epoxy resin, the inert CA powder was used either as unique inorganic filler (up to 30 wt%) or admixed to conventional ones (barite), in varying proportions (up to 10 wt%). Mechanical tests and SEM observations have shown encouraging results for all formulations, suggesting feasible reuse in this field.

The application of the inert CA powder as filler in fluor-elastomers in substitution of wollastonite (~22 wt%) or barite (~7 and ~14 wt%), has given some controversial results. Although rheological properties such as cure kinetics, viscosity and scorch temperature are comparable to the standard reference samples, some important physical-mechanical properties worsen because of compatibilization and dispersion problems. As demonstrate by SEM observations, the CA powder tends to agglomerate, and similarly to the coarser particles saved from ball-milling – the grain size distribution of the CA powder is tri-modal with peaks at ~35-40, ~4-5 and ~0.7-0.8 µm – separate from the elastomer, adding porosity with detrimental effects on breaking load, elongation at fracture and related M50 and M100 modules.

At the moment, in a perspective to keep the fine fraction low and to reduce the coarse particles, alternative milling procedures, including microwave and ultrasonic treatments and sieving, are evaluated.

Reference: Vergani et al. (2021) J. Mater. Cycles Waste. https://doi.org/10.1007/s10163-021-01320-6

How to cite: Fabrizio, V. and the Progetto Dear: Reuse of deactivated cement-asbestos waste as inorganic filler in elastomers and epoxy resins, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4981, https://doi.org/10.5194/egusphere-egu22-4981, 2022.

11:09–11:16
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EGU22-5607
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On-site presentation
Ana Teresa Lima et al.

Metals, including rare earth elements (REE), are the cornerstone of our current and future low-carbon urban infrastructure. This study looks at different waste resources and contaminated materials present in the urban setting as REE sources. Wastes and other dilute sources such as incineration ashes, sediments, and mine tailings are not only essential sources of REE in achieving a circular, carbon-neutral economy but may be the most realistic one. E-waste, being the most REE concentrated waste, faces serious reservations regarding handling in largescale facilities, and this waste is generally landfilled. After analyzing different residues, coal fly ashes and stormwater retention pond sediments present the most promising ones. While coal fly ashes have the highest critical REE contents from the studied wastes, the sediments collected from a stormwater retention pond showed the highest REE leachability. Critical REE Nd, Dy, and Er can mainly be found in sediments/soils near highways, coal ashes, and bauxite residue. Overall, coal fly ashes contain the highest critical REE contents found in the studied wastes but sediments collected from stormwater water ponds present the highest leachable REE. In fact, up to 100% of total REE found in these sediments are leachable at room temperature low pH. Future REE resource extraction efforts should account for REE speciation in wastes and not only total contents.

How to cite: Lima, A. T., Kirkelund, G., Ntuli, F., and Ottosen, L. M.: Screening dilute sources of rare earth elements for their circular recovery , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5607, https://doi.org/10.5194/egusphere-egu22-5607, 2022.

11:16–11:23
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EGU22-6391
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ECS
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On-site presentation
Pierluigi Zerbino and Davide Aloini

Abstract. The Circular Economy (CE) aims to reduce harmful emissions and soothe the pressure on raw material extraction by slowing, closing, and narrowing material and energy loops (Geissedoerfer et al., 2017). In stark contrast to this objective, CE can be environmentally unsustainable. A prominent reason is the Circular Economy Rebound (CER). CER is a phenomenon that occurs when a CE practice, which reduces per-unit production environmental impacts, causes increased levels of production and consumption that offset the environmental benefits (Zink and Geyer, 2017).
CER can impede CE strategies from achieving the intended benefits (Levanen et al., 2021). Moreover, overlooking it may lead firms to overstate their environmental performance. Nevertheless, CER is a largely unaddressed topic that deserves further empirical attention (Goyal et al., 2021). In particular, little to none has been conceived to cope with it (Salvador et al., 2020). Accordingly, this work aims to respond to the following research question: “What strategies may a firm undertake to manage CER?”.
To answer the research question, an exploratory single case study was developed. The chosen case was a marble import-export Italian firm. The unit of analysis was the CE initiative that allowed the firm to “close the loop” in its Supply Chain. The data were collected through semi-structured interviews and analysis of documentation and archival records concerning production.
The selected firm purchases marble blocks and transforms them into slabs that are sold worldwide. The transformation generates 240 t/year of slats that, before 2018, were disposed of. Since 2018, the firm has been remanufacturing the slats to create upcycled slabs that are similar to mosaics. However, this strategy exhibits massive CER (111.7%) due to the complete lack of displacement between primary and secondary products.
Through the analysis of the evidence, a guideline was developed to manage CER. The guideline presents five actionable insights that may help firms in pursuing their CE addresses through a set of Supply-Chain-wide strategies.

References
Geissdoerfer, M., Savaget, P., Bocken, N.M.P. and Hultink, E.J. (2017), “The Circular Economy – A new sustainability paradigm?”, Journal of Cleaner Production, Vol. 143, pp. 757-768
Goyal, S., Chauhan, S. and Mishra, P. (2021), “Circular economy research: A bibliometric analysis (2000–2019) and future research insights”, Journal of Cleaner Production, Vol. 87.
Levanen, J., Uusitalo, V., Harri, A., Kareinen, E. and Linnanen, L. (2021), “Innovative recycling or extended use? Comparing the global warming potential of different ownership and end-of-life scenarios for textiles”, Environmental Research Letters, Vol. 16, No. 5.
Salvador, R., Barros, M.V., Luz, L.M.D., Piekarski, C.M. and de Francisco, A.C. (2020), “Circular business models: Current aspects that influence implementation and unaddressed subjects”, Journal of Cleaner Production, Vol. 250.
Zink, T. and Geyer, R. (2017), “Circular Economy Rebound”, Journal of Industrial Ecology, Volume 21, No. 3, pp. 593-602.

How to cite: Zerbino, P. and Aloini, D.: Circular Economy Rebound: A case-based management guideline, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6391, https://doi.org/10.5194/egusphere-egu22-6391, 2022.

11:23–11:30
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EGU22-6971
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On-site presentation
Vojtech Ettler et al.

Gallium (Ga) and germanium (Ge) are technologically essential critical elements. This study focuses on old metallurgical slags generated by processing non-ferrous metallic ores in Tsumeb, northern Namibia, containing interestingly high concentrations of these elements (up to 156 ppm Ga and 441 ppm Ge). Mineralogical investigation indicated that the slags were composed of olivine-, melilite- and spinel-group phases, metal(loid)-rich glass, and sulfide/metallic inclusions. The FEG-EPMA and LA-ICP-MS data confirmed that major carriers of Ga were Zn-Fe-Al spinels (up to 1370 ppm), and Ge was primarily bound in a glassy phase (up to 470 ppm), especially in the case of granulated slags. The abiotic extraction tests, simulating a hydrometallurgical recovery via agitation leaching, were carried out in sulfuric, nitric, and hydrochloric acids (pH = 0.2-0.3, 25 °C and 70 °C, pulp density of 1%) to determine the release of Ga and Ge from slags. Their leaching attained a steady state after 6 hours for granulated slags and 2 hours for finely ground slags. The extractability of both Ga and Ge was slightly higher for the high-temperature trials. The overall recovery was the best for the sulfuric acid extractions and attained 100% and 96% for Ga and Ge, respectively. Our investigation indicates that understanding the specific binding of critical elements is crucial for their potential recovery from slags. This study was supported by the Czech Science Foundation project (GAČR 19-18513S).

How to cite: Ettler, V., Mihaljevic, M., Jedlicka, R., Kribek, B., Mapani, B., Kamona, F., Bowell, R. J., and Hrstka, T.: Gallium and germanium in metallurgical slags: mineralogy and potential recovery, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6971, https://doi.org/10.5194/egusphere-egu22-6971, 2022.

11:30–11:37
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EGU22-7014
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ECS
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On-site presentation
Luca Pellegrino et al.

Asbestos-containing material (ACM) still represents an emergency in Europe because of the related health problems. Based on dedicated legislation, ACM must be managed through several different operations such as: i) confinement, ii) encapsulation and iii) removal (with disposal in controlled landfills). A more attractive alternative to these non-ideal solutions, safer and sustainable, is the transformation of the ACM through thermal, thermo-chemical or thermo-mechanical methods into a non-hazardous secondary raw material. In this contribution, we explore the re-use of ACM thermally treated at 1100 °C in the production of sanitary ware ceramics.

Sanitary-ware vitreous bodies (VB) are generally obtained from mixtures of three fundamental raw materials: i) clay, mostly kaolinite, which provides plasticity to the ceramic mixture; ii) quartz, which acts as filler, forming the skeletal network of the ceramic body; iii) feldspar, a fluxing agent, which promotes the greification of the body and the dissolution of component like quartz upon firing (buller T 1200-1240 °C; Carty & Senapati, 1998).

The product of the thermally treated ACM, i.e. a mixture of non-hazardous Ca-Mg-rich silicates (akermanite, bredigite, merwinite and larnite) and glass, was added to a ceramic mixture as a partial substitute (5 wt%) of feldspar (mixture VBX), and characterized according to a standard protocol before and after firing in the industrial tunnel kiln (buller T 1230°C). The results pointed out a very good greification level of the VBX slip, as corroborated by very low water absorption. These results motivated us to better evaluate the greification behavior of the VBX slip at 6 different buller T by means of gradient kiln. From the mixture VBX, we prepared six samples which were heated at 1140, 1160, 1180, 1200, 1220, and 1240 °C, and characterized the mechanical, mineralogical and microstructural properties. For comparison, the same T steps and analyses were applied to six standard ceramic mixtures (i.e., vitreous China, VC).

XRPD indicates that VBX and VC have very similar mineralogical composition, with glass, quartz, feldspar and mullite as major constituents and minor Fe and Ti oxides. SEM observations suggest that VBX and VC have also similar microstructure, dominated by a glassy matrix embedding numerous 10-60 µm-sized particles of quartz, feldspar and mullite. Overall, thermally treated ACM seems a good candidate to substitute feldspar up to 5 wt% in the production of sanitary ware ceramics. This conclusion is further supported by the fact that VBX and VC display a very similar greification level at T>1200°C.

Carty, W. M., & Senapati, U. (1998). Porcelain—raw materials, processing, phase evolution, and mechanical behavior. Journal of the American Ceramic Society, 81(1), 3-20.

How to cite: Pellegrino, L., Bernasconi, A., Galimberti, L., Vergani, F., Marian, N. M., Viti, C., and Capitani, G.: Recycling of thermically treated asbestos-containing material in the production of sanitary-ware vitreous bodies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7014, https://doi.org/10.5194/egusphere-egu22-7014, 2022.

11:37–11:44
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EGU22-7741
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ECS
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Virtual presentation
Patrick Cito Namulisa et al.

Studies on worm-composting or vermicomposting, the addition and use of worms to recycle food and other organic wastes into a nutrient-rich product called vermicast, have shown that when used as soil amendment or activator, they have numerous positive effects on soil physico-chemical properties including: soil aeration, water-holding capacity, nutrient supply and they could be valuable peat substitutes in nursery production. Furthermore, vermicompost is an interesting proposition in the circular economy, particularly with food wastes in peri-urban areas. Despite these advantages, some studies have indicated that worm produce potent greenhouse gases (GHG), notably nitrous oxide (N2O). It has been suggested that the addition of biochar (BC) to the systems worm-compost-soils could substantially reduce the N2O emissions. The use of Biochar (BC), a biomass pyrolysis by-product, as soil amendment has been proposed essentially for its vast carbon sequestration potential as a “nature based solution” to combat anthropogenic induced climate change.

In this study, in addition to quantifying the GHG emissions from the entire worm-composting process and assessing the impact of BC addition on the vermicomposting process, particularly the nitrous oxide emissions (N2O), we determined the potential influence of the timing of the BC addition, whether biochar added before (BC-Compost-worms) or after (Compost-BC-worms) in the initial hot composting process had an influence on overall GHG emission; targeting essentially how biochar (BC) reduces the GHG emissions from the wormication process. We followed right through to the crop production stage using spinach as a test crop, to both determine and compare the N2O emissions from conventionally grown and organically produced products in a greenhouse experiment. To fully assess and compare these emissions from compost, compost-worms and biochar (BC) additions, we also added a treatment with equivalent inorganic fertilizer using nitrogen stable isotope (15N) labelling with the aim to see the pathway of the fertilizer, matching the nitrogen uptake with observed emissions.

In all seven treatments were established: compost only, compost worms, BC-Compost worms, Compost-BC worms, equivalent inorganic 15N fertilizer, soil only, and soil only no plants. Using a novel experimental set-up and cavity ring down laser based flow through system for analysis we explored the impacts of treatments on both GHG emissions and plant production. Our central hypothesis is that biochar will reduce N2O emissions from the worm treatments and that, this will lead to greater reductions in worm emissions when BC is added after (Compost-BC-worms) the initial hot composting process than compared to when added before (BC-compost-worms). The results and conclusions of this study will be presented.

How to cite: Namulisa, P. C., Heiling, M., Grand, A., Resch, C., Dercon, G., and Hood-Nowotny, R.: Greenhouse gas emissions from worm-compost-biochar combinations from farm to production to fork, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7741, https://doi.org/10.5194/egusphere-egu22-7741, 2022.

Thu, 26 May, 13:20–14:50

Chairpersons: Ana Teresa Lima, Pierluigi Zerbino

13:20–13:27
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EGU22-9769
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Virtual presentation
Cristina Maria Belfiore and Marco Viccaro

The presence of active volcanoes often influences human life both in terms of health impact and socio-economic consequences. Explosive eruptions can release into the atmosphere huge quantities of ashes which then fall to the ground, causing many inconveniences to communities living and working in close proximity to the volcano. A further problem is represented by the high costs that the involved administrations (Civil Protection or Municipalities) of the interested areas must face whenever this material, considered as waste, needs to be collected and disposed of in landfill.

To overcome this problem, it would be suitable to find ‘‘end of waste” alternatives for volcanic ash as raw material in the productive sectors, e.g., in building materials (tiles, bricks, mortars, concretes, etc.). A paradigm shift leading to consider ashes no longer as a waste but a resource.

This contribution deals with an experimental study aimed at assessing the possible re-use of volcanic ash as temper in the manufacture of ceramic tiles. Volcanic ashes recently erupted by Mount Etna volcano in Sicily (Southern Italy), one of the most active basaltic volcanoes in the world, have been here chosen as case study for such a purpose. Ceramic test-tiles were manufactured by mixing volcanic ash with a calcareous clayey raw material, by using specific proportions of clay/temper. In order to assess the quality of the products, the tiles underwent several physical–mechanical tests including: a) water absorption; b) bending resistance; c) impact resistance; d) resistance to deep abrasion; e) thermal shock resistance; f) frost resistance; and g) accelerated aging test by salt crystallization (Belfiore et al. 2020). The obtained results have been then compared with those of a reference product manufactured by using another volcanic material known as azolo (i.e., finely ground basalt) for a long time on the market. Our data demonstrate how basaltic ash recovering through this methodological approach is highly promising in the sector of building materials.

Reference

Belfiore C.M., Amato C., Pezzino A., Viccaro M., 2020. An end of waste alternative for volcanic ash: A resource in the manufacture of ceramic tiles. Construction and Building Materials, 263, 120118, doi: 10.1016/j.conbuildmat.2020.120118

How to cite: Belfiore, C. M. and Viccaro, M.: Recycling Etna volcanic ash for the production of ceramic materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9769, https://doi.org/10.5194/egusphere-egu22-9769, 2022.

13:27–13:34
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EGU22-11232
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ECS
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On-site presentation
Zijian Ren et al.

Aggregates (collectively sand, gravel, and crushed stone) are the most extracted material by weight over the world, and they are important raw materials for buildings and infrastructure. Owing to its rapid development, China is the largest aggregate consumer and producer, accounting for over half of the global aggregate consumption. However, aggregates in China are now facing shortages and low resource circulation. As a long-neglected resource, it is difficult to provide sufficient support for relevant policy-making without a comprehensive quantitative basis. To bridge the knowledge gap, first, we established a systematic material flow and stock accounting framework to map the social metabolism of aggregate resources in China. Then we discussed the results in the global context for international comparison to figure out the circularity gaps of aggregates in China. Our results show during 1978–2018, the inflows of China’s aggregates increased by 13 times (1.3 to 17.3 billion tons), the stocks increased by 15 times (18.3 to 285.5 billion tons), and the outflows, the main component of CDW, increased 9 times (from 445 million tons to 4.4 billion tons). On the supply side, a transition of the primary supply structure is observed. The manufactured aggregates gradually replaced the natural aggregates as the main supply source in the past decade. On the demand side, the demand for aggregates stepped to a peak of around 18.5 billion tons. The infrastructure rather than building becomes the main consumer since 2014. However, the model shows the recycling rate of outflows is less than 5%, indicating a circularity gap compared to the rate that could be as high as 70%–95% in certain advanced economies. The market acceptance, policy supports, and the structures of demolished buildings are the main reasons for the current circularity gap of aggregates. Regarding a large amount of aggregates accumulated in the material stocks, it is expected to see rapid growth of aggregate waste in the near future. It is essential to foster a well-functioned circular system to achieve the sustainable development of the aggregate industry.

How to cite: Ren, Z., Jiang, M., Chen, D., Yu, Y., Li, F., Xu, M., Bringezu, S., and Zhu, B.: Structure Transition and Circularity Gap of Sand and Gravel Resources in China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11232, https://doi.org/10.5194/egusphere-egu22-11232, 2022.

13:34–13:41
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EGU22-13539
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Virtual presentation
Margret Fuchs et al.

The steeply increasing demand for electronic devices and fast innovation cycles, combined with the recent political and societal orientations towards e-mobility and energy transition leads to vast amounts of e-wastes (i.e. Waste of Electrical and Electronic Equipment – WEEE). Most of the million tons of WEEE generated annually are only partially recycled up to now. This impedes dramatically EU goals towards Circular Economy. In order to improve recycling efficiency and thus minimize our environmental footprint, modern recycling plants need multi-component sensors that can identify complex materials rapidly and accurately. We address this challenge by using a combination of imaging sensors to identify key chemical compounds in material streams. Our main objective is the rapid mapping of the critical compounds in unknown, variable WEEE material streams. Such digital information is then immediately available for an adequate sorting and inherently adapted recycling that will enable Circular Economy. In this context, the RAMSES-4-CE project, which is funded by EIT innovates optical spectroscopy-based multi-sensor systems for the recycling industry. By means of hyperspectral (HSI) reflectance spectroscopy in the near- and mid-infrared range certain alloys, ceramics, and plastics can be identified and classified. Laser-induced fluorescence (LiF) spectroscopy enables the detection of rare earth elements (REEs) and low-reflective black plastics among others. In order to expand the range of WEEE classes which can be identified by our system, we propose to add a rapid, non-destructive and cost-efficient Raman sensor.  

To achieve the required innovation towards an efficient and smart sensor network, we focus on three major aspects: (1) developing a Raman sensor, (2) its integration in an existing LiF-HSI system (EIT inSPECtor project), (3) advanced multi-source data fusion via a rapid machine learning-based data integration. The combination of fast imaging sensors with a precise point validation sensor addresses the need for the identification of shredded recycling materials at high measurement speeds (up to 1 m/s) as well at high spatial resolution (about 2 mm) in industrial applications of sensor-based sorting. In this contribution, we present the RAMSES-4-CE sensor network concept of two integrated line-scan sensors (HSI, LiF) for rapid mapping combined with an adapted Raman point-sensor. The sensor network is mounted on top of a conveyor belt of about 50 cm width and can be adapted for the characterization of minerals/rocks in exploration and mining applications as well. Component identification is based on the comprehensive work on spectral fingerprints for plastics, semiconductors, REE and other critical WEEE components. In addition, we present our concept for a time-efficient data processing workflow to enable sensor communication and accordingly, allow for selected validation analysis to update the mapping results. The temporally and spatially resolved information enables then subsequent decision making in recycling processes. 

 

How to cite: Fuchs, M., de Lima Ribeiro, A., Arbash, E., Röder, C., Schüler, N., Dornich, K., Sheng, Y. X., Gloaguen, R., and Heitmann, J.: The RAMSES-4-CE project – developing a smart sensor network for e-waste characterisation , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13539, https://doi.org/10.5194/egusphere-egu22-13539, 2022.

13:41–13:48
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EGU22-13557
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Highlight
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Virtual presentation
Laura Ferrans et al.

Dredging activities are carried out worldwide to increase water levels in harbours and bays or restore the aquatic ecosystem. As a result, a large amount of extracted sediments are produced, and the material is widely disposed of at open seas or landfills. Legal and environmental regulations constrain traditional sediment disposal methods due to their potential contaminant pathways, lack of long-term stability, and limited space capacity. Finding new disposal routes for sediments becomes a challenge. Implementing beneficial uses for dredged material represents a proper way to eliminate sea dumping and embodies adequate disposal, reducing the extraction of raw materials. Around the world, several beneficial uses of sediments have been implemented. Productive and positive uses of dredged material include incorporation in construction, agriculture, land reclamation and habitat restoration, among others.

The recycling of dredged sediments depends on their composition. The material typically contains nutrients, metals and organic compounds, according to the discharges to water bodies since sediments are the final sink of discharged compounds. Sediments with a high organic matter content and nutrients and low pollution concentrations are feasible for soil conditioning purposes. Nutrients are essential for life, and elements such as phosphorous receive high importance since the element is limited on Earth. Additionally, phosphate mines are only located in a few parts of the world, potentially causing shortages due to geopolitics. Hence, investigating new sustainable sources of nutrients is required, and dredged sediments could be employed as an option. This study aims to present dredged material as a plant-growing substrate to cultivate lettuce (L. Sativa), tested under greenhouse conditions. Moreover, another objective was to assess the risk of metal pollution related to vegetable consumption. The case study is in Kalmar, southeast of Sweden. The dredged material comes from Malmfjärden bay. The water body is currently shallow, and its biodiversity is threatened by eutrophication and continuing siltation. Therefore, a dredging project was initiated to recover the bay.

Sediments from the dewatering system of the project were extracted to be employed in the greenhouse experiment. The material presented high content of nutrients and organic matter and medium-low content of metals. The sediments were mixed with compost to improve the physical conditions since they were mainly clay and silt (90%). The selected substrates were (1) 100% compost and (2) 50% sediments - 50% compost. The seeds were pre-germinated and transplanted into pots. The experiment was carried out for 3 months in stable conditions. The obtained lettuces (leaves and roots) were analysed to measure their metal content. The results showed that the plants grew in both substrates, and the harvested lettuce had leaves of a medium length. The metal contents in the vegetables were below critical levels detrimental to human health. The study concluded that the sediments were a potential source of nutrients, using the material as a plant-growing substrate. However, mixing with other organic materials (like compost) is recommended to improve the physical properties of sediments and improve their nutrient distribution and availability.

How to cite: Ferrans, L., Schmieder, F., and Hogland, W.: Dredged sediments: A new source of nutrients as a plant-growing substrate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13557, https://doi.org/10.5194/egusphere-egu22-13557, 2022.

13:48–13:55
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EGU22-13564
Lisbeth M. Ottosen et al.

Strontium came into the EU list of critical raw materials in 2020 [1]. Critical raw materials are essential to the functioning and integrity of a wide range of industrial ecosystems. The European Green Deal’s Circular Economy Action Plan [2] aims to decouple growth from resource use through sustainable product design and mobilizing the potential of secondary raw materials. Still, for Sr, recovery from secondary resources is currently very limited. The end-of-life recycling input rate (EOL-RIR) reflects the total material input into the production system that comes from post-consumer scrap recycling, and it is 0% for Sr [3].

This work explores the possibility of extracting Sr from three different types of incineration ashes. The ashes are: wood fly ash (WFA), sewage sludge ash (SSA), and municipal solid waste incineration (MSWI) fly ash. The experimental work includes two ashes of each type and from different Danish incineration plants.

 

The total Sr concentrations in the ashes were: WFAs 610 mg/kg and 500 mg/kg, SSAs 2021 mg/kg and 520 mg/kg, and in the MSWI fly ashes 260 mg/kg and 261 mg/kg. Thus, the WFAs and the MSWI fly ashes mutually had concentrations within the same level, whereas the SSAs varied more in Sr concentrations. A four-step sequential extraction was used. It showed very similar patterns for each ash pair but significant differences between the ash types. The SSAs had more than 70% Sr in the residual phase i.e., in the hardest bound fraction, and less than 10% in the first step i.e., easiest to extract. The MSWI fly ash had about 20% Sr in the residual phase and 35% in the first. The WFAs were in-between these two.

 

Extracting Sr from the ashes in HNO3 of different concentrations also showed different patterns, and the results were similar for each pair of ashes. At pH 5, about 100% Sr was extracted from the WFAs. At pH 5 the maximum extraction was obtained for the MSWI fly ashes, which was 65%, and no more was extracted even at pH of 0.3. At pH 1 about 100% Sr was extracted from the SSAs.

 

From the screening of three different ash types performed here, extraction of Sr has the highest potential for WFAs. They contain 500-600 mg Sr/kg, and at a pH of around 5, it was possible to extract about 100% of this resource.

 

Acknowledgment

This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045

 

References

[1] COM(2020) 474 Critical Raw Materials Resilience: Charting a Path towards greater Security and

Sustainability

[2] COM(2020) 98 A new Circular Economy Action Plan. For a cleaner and more competitive Europe

[3] Blengini, G.A., Latunussa, C.E.L., Eynard, U., Torres de Matos, C., Wittmer, D., Georgitzikis, K., Pavel, C., Carrara, S., Mancini, L., Unguru, M., Blagoev

How to cite: Ottosen, L. M., Hansen, H. K., Ribeiro, A. B., and Lima, A. T.: Screening of strontium extraction from different incineration ashes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13564, 2022.