ERE4.6 | Monitoring, treatment, and utilization of industrial solid wastes
EDI
Monitoring, treatment, and utilization of industrial solid wastes
Convener: Qiusong Chen | Co-conveners: Yikai LiuECSECS, Davide BernasconiECSECS, NYANDWE EUGENIE MUSONDAECSECS, SAKARIYAU BABATUNDE ABDULKADIRECSECS
Orals
| Thu, 18 Apr, 10:45–12:30 (CEST)
 
Room 0.16
Posters on site
| Attendance Thu, 18 Apr, 16:15–18:00 (CEST) | Display Thu, 18 Apr, 14:00–18:00
 
Hall X4
Posters virtual
| Attendance Thu, 18 Apr, 14:00–15:45 (CEST) | Display Thu, 18 Apr, 08:30–18:00
 
vHall X4
Orals |
Thu, 10:45
Thu, 16:15
Thu, 14:00
The widespread pollution stemming from the disposal of industrial solid waste has altered soil geochemistry and disrupted ecosystem functions. This crisis has manifested in many detrimental consequences, including acidification, trace metal contamination, and soil degradation. In light of the imperative to align with the United Nations' Sustainable Development Goals (SDGs) and ensure the sustainability of contemporary industrial practices, responsible and careful stewardship of solid waste management is paramount. Over recent decades, diverse disposal options have been proposed and critically evaluated by scientific organizations, which range from conventional landfill/dumping methods to more sustainable treatments such as solidification/stabilization, biological remediation, electrokinetic processes, and phytoremediation. It is noteworthy, however, that certain strategies may inflict more detrimental impacts on the environment when considering their entire life cycles than simply taking no action. Furthermore, factors such as the depletion of traditional disposal sites, increasingly stringent environmental regulations on waste disposal, and the increase in the volume of industrial solid wastes, particularly in industrialized nations, have led to a rapid increase in the cost of waste disposal services. Thus, the blueprint for future waste management plans should revolve around a profound understanding of the enduring resilience of these systems and a resource-efficient paradigm for waste control. This will involve a wide range of scientific issues, such as the long-term resilience of the immobilized product over time when entering local biogeochemical processes and ecosystem dynamics, how to use quantitative and/or qualitative simulations to demonstrate the safety of disposal, how to assess the carbon footprint of the entire system, etc.
In this session, we will discuss the following scopes, but not limited to:
-In-depth analysis and characterization of industrial solid waste
-Innovative tools and methodologies in active and legacy sites for risk monitoring
-Identification of potential secondary resources for rare earth elements recovery
-Contaminant leaching and environmental impact assessment
-Advanced recycling processes (e.g., carbonation, solidification/stabilization, and chemical processing)
-Interaction of surrounding environment with waste constituents
-Geochemical and reactive transport modeling for industrial solid waste disposal

Orals: Thu, 18 Apr | Room 0.16

Chairpersons: Qiusong Chen, Yikai Liu, Davide Bernasconi
10:45–10:50
10:50–11:00
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EGU24-631
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ECS
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Highlight
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On-site presentation
Quentin Wehrung, Linda Pastero, Enrico Destefanis, Caterina Caviglia, Simona Cavagna, Andrea Cotellucci, and Alessandro Pavese

The urgent need to mitigate carbon dioxide (CO2) emissions and address climate change has propelled the exploration of innovative approaches for carbon capture and storage (CCS). Among these, the carbonation of Industrial Alkaline Wastes (IAW) emerges as a promising avenue. In the design of a carbonation process, the primary challenges revolve around enhancing the CO2 absorption rate while minimizing energy consumption and water demand. This holds true irrespective of the nature of the gas stream—whether it be flue gas, pure CO2, or even air. Beyond the storage of CO2, the main co-benefit of IAW carbonation lies in the value added through waste stabilization, facilitating its reutilization.

The study seeks to contribute to the optimization of carbonation reactors by providing a comprehensive understanding of the relevant factors influencing both the CO2 absorption rate and the waste stabilization during MSWIA aqueous carbonation in open systems. The investigation considers Ca(OH)2, Mg(OH)2, and MSWIA carbonation individually, with a focus on free Ca and Mg oxides/hydroxides as the main phases providing cations for carbonation to occur. The detailed exploration of operational parameters aims to guide the design of efficient strategies, addressing the critical question of "How can an IAW carbonation reactor be optimized to achieve maximum CO2 absorption, high yields, and stable byproducts?". The investigated operational parameters include:

  • Ca(OH)2, Mg(OH)2, MSWIA initial concentrations;
  • CO2 flow rate;
  • CO2 concentration in the gas stream;
  • Temperature;
  • NaCl concentration (salinity);
  • NaSO4 concentration as accumulating impurities;
  • MSWIFA concentration as accumulating impurities;
  • Mixing system, with a comparison of bubbling (pipe), sparger and porous stone diffusor;
  • Ball-milling of MSWIFA for particle size reduction;
  • One-step vs two-step process (mineral extraction through pH-swing).

An experimental dataset, based on batch experiments, was collected using high-precision gas flow sensors to measure the percentage of flowing CO2 absorbed by the reactor under a wide range of operational conditions. Leaching tests were carried out according to the EN 12457-2 standard on solid waste. Solid-liquid phases characterisation was conducted using XRPD with Rietveld refinement, SEM-EDS and ICP-MS. A computational set comprising equilibrium and dissolution kinetic models was developed using Phreeqc to interpret CO2 absorption vs. time patterns as well as the pH dependence of the MSWIA leaching.

We acquired numerous relevant findings:

  • Ca/Mg (hydr-)oxides dissolution is widely considered as the main rate-controlling step for IAW carbonation over CO2. Using a CO2 diffusion systems, we have shown that increasing the CO2-water interfacial surface area by reducing the size of the bubbles causes a cascade of kinetic acceleration of dissolution.
  • The average NaCl seawater concentration, 3.5 wt.%, optimizes the CO2 absorption rate.
  • By employing CO2 sparger/porous stone diffusion alongside a 3.5 wt.% NaCl concentration, it becomes feasible to achieve an absorption rate exceeding 90 % for 2 L/min of CO2 when using a solution with 7.5 wt.% Ca(OH)2 in just 1 kilogram of water.

These insights pave the way for more energy-efficient and environmentally sustainable IAW reactor designs with the potential for widespread application in carbon capture and storage efforts. 

How to cite: Wehrung, Q., Pastero, L., Destefanis, E., Caviglia, C., Cavagna, S., Cotellucci, A., and Pavese, A.: Industrial Alkaline Waste Carbonation: Challenges and Opportunities. The case of Municipal Solid Waste Incineration Ashes (MSWIA), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-631, https://doi.org/10.5194/egusphere-egu24-631, 2024.

11:00–11:10
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EGU24-6954
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ECS
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On-site presentation
Daolin Wang, Qinli Zhang, and Yunbo Tao

As a bulk by-product of the chemical phosphoric acid industry, phosphogypsum (PG) has not been effectively utilised because of the large number of impurities, and the large amount of stockpiled on the surface of the ground poses a potential risk of environmental pollution due to the leaching of its harmful elements. Therefore, the current consideration is to combine the bulk consumption of PG with the management of the underground mining area by cementing paste backfilling technology (CPB), so as to realise the harmless disposal of PG in the management of the mining area at the same time. However, there are several scientific problems as follows:

  • PG has a large amount of phosphoric acid residue in the output process, which makes the pH of phosphogypsum around 2~3, and it is difficult to meet the alkaline environment requirements for cement hydration.
  • The poor cementing properties of PG and silicate cement lead to limited development of the strength of the PG backfilling body, and increasing the proportion of cementitious materials is bound to increase the cost of backfilling.
  • Although PG cemented backfiller can fix/stabilise most of the harmful elements leaching pollution, according to the preliminary experimental research, the fluorine leaching amount in the backfiller is still far more than the original groundwater quality grade standard (>2.0mg/L).

Therefore, on the basis of CaO neutralisation and modification of PG, we choose diversified active solid wastes such as steel slag and slag as backfilling cementitious materials, and use PAC or biochar as targeted fluorine fixation materials. Afterwards, we can obtain the parameters of PG backfilling ratios in line with the requirements of strength and environmental protection through a large number of experiments. The hydration and fluorine leaching mechanisms were explained by XRD, EPMA-WDS, heat of hydration test, compressive strength test and fluorine leaching test.

How to cite: Wang, D., Zhang, Q., and Tao, Y.: Research on the transformation and immobilization mechanism of fluorine-containing phase in phosphogypsum low-carbon gel backfilling system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6954, https://doi.org/10.5194/egusphere-egu24-6954, 2024.

11:10–11:20
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EGU24-1777
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ECS
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Highlight
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On-site presentation
Abdullah Basaleh, Muhammad Al-Malack, Tawfik Saleh, and Bassam Tawabini

An effective magnetic polymeric composite was produced from steelmaking waste in this work. For the elimination of methyl orange MO and methylene blue MB from synthetic solutions, steel slag was treated with an acrylamide acrylic acid (SSAA) copolymer. TGA thermogravimetric analysis, SEM scanning electron microscope, XRD X-ray diffraction, BET Brunauer-Emmett-Teller surface area, and FTIR Fourier transform infrared were used to analyze the SSAA composite. The SSAA adsorption behavior for MO and MB was studied, and the impact of various factors was analyzed using one factor at a time (OFAT) and the RSM-BBD response surface method-Box Behnken Design. The second-order kinetic model accurately described the kinetic data of MO and MB, and the primary rate-limiting phase is film diffusion. The Dubinin-Raudshkevish (D-R) and Freundlich isotherms accurately characterized the MB and MO experimental outcomes, respectively. MO and MB had maximal absorption efficiencies of 97% and 94%, respectively, and capacities of 47 and 463 mg/g. The thermodynamic studies revealed that MO and MB adsorption on the SSAA was favorable and spontaneous. Physical adsorption was discovered to be the dominant mechanism for MB, whereas chemisorption was identified for MO. The regeneration investigation verified these mechanisms, in which SSAA was regenerated for MB and a negligible decline in adsorption capacity was seen after five cycles. However, for MO ions, a minor renewal of the SSAA was achieved, confirming the chemisorption mechanism. According to the thermodynamic study, the SSAA composite might be employed for the removal of cationic and anionic dyes from wastewater spontaneously and feasibly.

How to cite: Basaleh, A., Al-Malack, M., Saleh, T., and Tawabini, B.: Utilization of steelmaking waste as a sustainable low-cost adsorbent for cationic and anionic dyes removal , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1777, https://doi.org/10.5194/egusphere-egu24-1777, 2024.

11:20–11:30
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EGU24-5156
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Highlight
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Virtual presentation
Zhuoran Wang, Xiaozhong Gu, and Haiqiang Jiang

The hydration of alkali-activated slag (AAS) is highly sensitive to the curing temperature, especially at early ages. In low temperature environment, cemented paste backfill made of AAS (AAS-CPB) exhibits notably reduced early-age uniaxial compressive strength (UCS), attributable to the inhibitory effect of low temperature on slag hydration. This study aims to improve the performance of AAS-CPB at low temperatures by incorporating chemical additives. The results shows that calcium salts, specifically CaCl2, CaSO4, and Ca(COOCH3)2, can increase the early-age UCS of AAS-CPB by up to 1050%, depending on the specific anion involved. Overall, CaCl2 provides the greatest enhancement in the UCS. However, the presence of these salts result in strength degradation at later ages. A pronounced exponential relationship is evident between UCS and ultrasonic pulse velocity. The change of conductivity and moisture content are valuable indicators of hydration process at low temperatures. C(N)-A-S-H, hydrotalcite and portlandite are the primary hydration products. Anions play a decisive role in the morphology, precipitation and quantity of C(N)-A-S-H. The slag hydration degree and UCS basically exhibit a consistent trend. 

How to cite: Wang, Z., Gu, X., and Jiang, H.: Improving early-age performance of alkali-activated slag paste backfill with calcium salts at low temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5156, https://doi.org/10.5194/egusphere-egu24-5156, 2024.

11:30–11:40
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EGU24-515
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ECS
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On-site presentation
Sneha Das and Sandip Mondal

Through this study, a novel method for producing magnetic biochar from waste wood sourced from Acacia auriculiformis is achieved. Slow pyrolysis method of biochar was used for the conversion of waste wood which in turn proved to be more efficient than other procedures. Nanoparticles which were successfully deposited onto the surface of biochar were derived from iron powder transformed into iron-oxide. High specific surface area of 266.564 m2g-1 was achieved through Brunauer–Emmett–Teller (BET) analysis. Scanning Electron Microscopy (SEM) images demonstrate the formation of triangular pyramid-shaped nanoparticles in the adsorbent's inner and outer wall pores. Fe3O4 was coated on the surface of the adsorbent in a crystalline, carbonaceous form, as indicated by XRD peaks. A number of hydroxyl and aliphatic stretching bonds of carbon serve as functional groups in the impregnation and anionic targeted pollutants adsorption process, according to FTIR research. The establishment of the best-fit model for several anionic pollutants followed the method of multi-layer heterogeneous adsorption. Removal efficiencies of 95%, 85%, and 80% of arsenic, chromium, and fluoride are attained, respectively. Kinetic models were used to determine the adsorption process. Surface mechanism involved electrostatic attraction followed by pseudo first, second order, Bangham equation and Weber Morris intra-particle diffusion and complexation helping in adsorption of the anionic ions. Whereas, chromium and fluoride followed Temkin and Dubinin-Radushkevich adsorption isotherms. The maximum capacity of the manufactured biochar for arsenic, chromium and fluoride is estimated to be 294.1176, 204.22 and 102.36 mgg-1 respectively. Regeneration studies showed that upto 80-90% of ions can be recovered from the magnetic biochar.

How to cite: Das, S. and Mondal, S.: Separation and recovery of anions from aqueous solution through iron oxide nanoparticle impregnated biochar derived from waste wood, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-515, https://doi.org/10.5194/egusphere-egu24-515, 2024.

11:40–11:50
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EGU24-3326
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Virtual presentation
Yan Feng, Cunyu Zhao, Qinli Zhang, and Daolin Wang

Ordinary Portland Cement (OPC) is the most widely used cementitious material in cemented paste backfill at present. However, OPC production consumes massive energy and is one of the main contributors to greenhouse gas emissions. Hybrid alkali-activated cement (HAAC) is a promising alternative to Ordinary Portland Cement (OPC), mainly consisting of supplementary cementitious materials (SCMs), OPC, and alkali activators. This innovative solution not only reduces energy consumption but also mitigates carbon footprint compared to OPC production. Moreover, it is worth noting that the production process of widely used commercial alkali activators, including sodium hydroxide and sodium silicate, is associated with notable energy consumption and environmental pollution. Therefore, addressing these concerns is essential for enhancing the sustainability of HAAC and making it an environmentally friendly choice in cemented paste backfill.

Red mud (RM) is a by-product generated by the Bayer process during the production of alumina from bauxite, which is a potential alternative to commercial alkali activators due to its high alkalinity. The experimental results show that the cemented paste backfill with RM-NaOH activated slag cement exhibits higher compressive strength than that with OPC or NaOH activated slag cement as binders in different curing ages. By comparing the Life Cycle Assessment (LCA) results, the RM-NaOH activated slag cement shows reductions mainly in the environmental impact categories of terrestrial acidification potential (TAP), fossil depletion potential (FDP), ozone depletion potential (ODP), and global warming potential (GWP). The total environmental impact of RM-NaOH activated slag cement is reduced by 13.67% compared to OPC, indicating that the production of HAAC with RM as the primary activator would significantly decrease the environmental effect of OPC manufacturing.

How to cite: Feng, Y., Zhao, C., Zhang, Q., and Wang, D.: Using Bayer red mud as an alternative activator in hybrid alkali-activated cement for cemented paste backfill: Experimental investigation and life cycle assessments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3326, https://doi.org/10.5194/egusphere-egu24-3326, 2024.

11:50–12:00
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EGU24-13218
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ECS
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On-site presentation
Elias Arbash, Margret Fuchs, Behnood Rasti, Sandra Lorenz, Pedram Ghamisi, and Richard Gloaguen

In the quest for achieving the principles of a circular economy, our Helios Lab seeks to optimize the e-waste recycling industry with its innovative Ramses-4-CE project (KIC RM 19262). Ramses focuses on the development of a smart network comprising multimodal optical non-invasive sensors mimicking industrial scenarios with a conveyor belt that can attain speeds of several meters per second. The primary objective is to facilitate the comprehensive identification and characterization of e-waste materials, particularly printed circuit boards (PCBs), plastics, and rare earth elements (REE).

The sensor ensemble encompasses a laser profiler generating height maps, an RGB camera capturing surface spatial features, hyperspectral cameras capturing the spectral features, and chemical characteristics obtained with a Raman spectroscopy sensor affixed to a robotic arm. Each sensor type offers unique advantages and inherent challenges. RGB cameras with their data facilitate fast, highly accurate, and smart data processing e.g., using machine learning (ML) and deep learning (DL) object detection and segmentation techniques in shredded plastics, while hyperspectral imaging (HSI) aids in polymer identification based on spectral fingerprint libraries. Nonetheless, HSI poses challenges such as large data size due to its abundant information, noise interference, and overlong processing times.

To optimize the data processing pipeline, meticulous preprocessing and processing methods have been devised. Upon data acquisition of different objects and materials, data co-registration is executed on the resulting RGB images and hyperspectral cubes, followed by object detection and segmentation of valuable objects on both data types. For objects eluding identification via RGB and hyperspectral imagery, a Raman spectroscopy-based validation is involved for detailed chemical analysis.

Yet, exerting high accuracy in HSI pixel-wise classification on multi-unseen data cubes necessitates HSI classification models with robust generalization capabilities. Towards this aim, smart automated masking of undesired objects in the hyperspectral scene is developed. HS cube contains abundant data causing their large volume size. This abundance highlights the useful information, while concurrently amplifying noises and artifacts, detrimentally affecting both data processing speed and model generalization. Masking undesired objects in the HSI reduces the number of pixel vectors skewing calculations in preprocessing steps and DL models training routines, leading to enhanced segmentation models, i.e., masking unwanted data vectors from HSI allows exclusive processing for desired targets elevating processing speed without compromising accuracy. 

How to cite: Arbash, E., Fuchs, M., Rasti, B., Lorenz, S., Ghamisi, P., and Gloaguen, R.: Ramses-4-CE: Towards Enhanced Generalization of RGB/Hyperspectral Imaging Data Processing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13218, https://doi.org/10.5194/egusphere-egu24-13218, 2024.

12:00–12:10
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EGU24-15399
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ECS
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Virtual presentation
Estela Pérez, Javier Rodrigo-Ilarri, and Maria-Elena Rodrigo-Clavero

The implementation of efficient municipal waste management systems is crucial to address current environmental challenges. These systems allow for the minimization of waste generation, promotion of reuse and recycling, and proper management of remaining waste. By reducing the amount of waste sent to landfills, soil, water, and air pollution decreases, and the emission of greenhouse gases is limited. Moreover, efficient municipal waste management fosters the circular economy by recovering valuable resources from waste, thereby contributing to the conservation of raw materials and long-term sustainability.

This work presents a methodology for urban waste management tailored to medium-sized municipalities (approximately 10,000 inhabitants). It highlights the resources and tools available at the municipal level to achieve the objectives set by European Directives on waste management. These resources encompass environmental communication and information, economic, fiscal, and regulatory instruments, as well as a proposal for a model of urban solid waste collection.

The proposed methodology is applied to the municipality of l'Alcora (Castellón, Spain), whose current management model relies on anonymous municipal waste collection, where citizens voluntarily decide where to dispose of their waste based on their environmental awareness, without any form of reward or penalty for their actions. This voluntariness and limited promotion of environmental awareness have led to a general lack of interest among the population in waste management. This situation has, in general, caused Spain to lag behind other EU member states in achieving the goals of waste prevention, valorization, and recycling set by the European Union.

How to cite: Pérez, E., Rodrigo-Ilarri, J., and Rodrigo-Clavero, M.-E.: Implementing a new model of urban solid waste management at a local scale: application to the municipality of l'alcora (castellón, spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15399, https://doi.org/10.5194/egusphere-egu24-15399, 2024.

12:10–12:20
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EGU24-15407
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On-site presentation
Orlando Vaselli, Federica Meloni, Barbara Nisi, Marcello Panarese, Jacopo Cabassi, Giordano Montegrossi, and Ivan Fagiolino

KEU (Kraftanlagen Energie und Umwelttechnick) is a by-product of a pyrolyzed waste of sewage sludge produced by wastewater treatment from tannery industries. KEU is regarded as an industrial non-hazardous waste after inertization to obtain a sintering granulate and usually mixed with demolition-construction or industrial mud products to produce EoW (End of Waste) material. However, the resulting materials are apparently responsible of the anomalous concentrations of Cr and CrVI and other PTEs (Potentially Toxic Elements), recovered in several domestic wells distributed along the Siena-Empoli motorway (Tuscany, central Italy) since KEU was used as roadbed. Similar concerns were also evidenced in other areas, as in the local groundwater system, where the KEU industrial by-product is stored, anomalous contents of heavy metals were determined.

In this work, an extensive analytical work was conducted to characterize the mineralogical and chemical bulk composition of eight KEU-bearing samples collected from different cumulus stored in an aggregate crushing plant and one pyrolysis char (the KEU) sample. It is remarkable the presence of high Rare Earth Elements (REEs) concentrations. While pure KEU has total REEs of 14 mg/kg, the KEU-bearing materials are up 4300 mg/kg.

To verify whether the KEU-bearing samples were able to release PTEs, three leaching tests (after 1-hour, 1-day and 7-days) were performed by shaking 20 g in 200 mL of MilliQ and 20 g in 200 mL of CO2-saturated MilliQ water, the latter simulating the interaction between meteoric waters and KEU-bearing materials. The resulting suspensions of all the aliquots were centrifuged and the surnatant was analyzed for pH, electrical conductivity, main composition, CrVI and trace elements. The 1-day post-centrifugation residue was leached and shaken for 7 days to evidence whether the PTEs were still released after a relatively long-term leaching. The analytical results showed that the MilliQ water leachates have high pH values (up to 11.75) whereas those obtained by CO2-saturated MilliQ partly buffer the pH although moderately alkaline pH values were measured. Our study indicates that, as expected, in most cases the CO2-saturated MilliQ water is able to more efficiently scavenge PTEs than those solubilized by MilliQ water. Moreover, the 1-day leachates resulted to be enriched in many PTEs with concentrations, in most cases, from hundreds to thousands microg/L. Despite a general decrease, in the 7-days leachates, high contents of some heavy metals were still measured, suggesting that prolonged interaction between meteoric waters and the KEU-bearing materials is able to transfer PTEs to the groundwater systems. The 1-hour and 1-day leachates showed relatively high concentrations of CrVI (from 20 to 1370 microg/L) while REEs were always approaching the detection limit or below it. Another important aspect is that the investigated samples are chemically heterogeneous, indicating that the inertization process was not performed by using the same amount of demolition and construction materials although the main composition was mostly Ca-SO4. Notwithstanding such an inertization, aimed at stabilizing unwanted toxic elements, its efficiency is rather scarce and, consequently, its use as by-product is strongly discouraged unless a more adequate inertization process is applied.

How to cite: Vaselli, O., Meloni, F., Nisi, B., Panarese, M., Cabassi, J., Montegrossi, G., and Fagiolino, I.: When environmentally friendly solutions are worse than the contaminated product: the KEU case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15407, https://doi.org/10.5194/egusphere-egu24-15407, 2024.

12:20–12:30
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EGU24-19079
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On-site presentation
Ana Paola Becerra Quiroz, Johanna Karina Solano Meza, María Elena Rodrigo-Clavero, and Javier Rodrigo-Ilarri

The organic fraction of municipal solid waste (OFMSW) represents between 40% and 50% of the solid waste of a megacity and despite its great potential for use, continues to generate environmental problems, which highlights the need to continue the search for sustainable and efficient solutions [1].  Current research processes have been geared towards anaerobic digestion (AD) as a promising technology to treat this waste. To this end, this study focuses on examining variables and mathematical models to precisely implement AD processes in a megacity, while exploring its technical and economic feasibility to address the increased amounts of these wastes, in order to optimize current technological developments.  

In megacities such as Bogotá, the case study area for this research paper, addressing the environmental, social and public health impacts generated by OFMSW is of the utmost importance. Anaerobic digestion is projected as an innovative and sustainable alternative, which not only contributes to treating waste, but also as a source of renewable energy, in addition to generating valuable by-products for agriculture. However, successfully applying AD in a megacity requires an in-depth analysis of the processes involved and the examination of multiple variables for its integration into models that become essential decision-making tools.

The following are among the technical variables of analysis for these processes and their subsequent modeling: OFMSW composition, temperature, carbon-to-nitrogen ratio, pH, volatile fatty acids and the presence of inhibitors as critical factors that impact AD performance. Given this scenario, having an adaptive approach that ensures predictive and consistent results over time is indispensable. In addition to these variables, aspects associated with economic, environmental, and social viability should be included, such as population size and projections, climate variability and seasonality, costs associated with the comprehensive service, correct separation at the source, policies and governance models, and land use plans established within the development plans of the cities[2]. Thus, the results obtained from this research study will provide a comprehensive understanding of the factors, processes and variables that influence the efficiency of AD of OFMSW in a megacity. These findings will not only contribute to the design of more efficient systems, but also support decision-making processes, as well as the formulation of waste management strategies, policies and practices at the city level.

[1]      L. M. Ulloa-Murillo, L. M. Villegas, A. R. Rodríguez-Ortiz, M. Duque-Acevedo, and F. J. Cortés-García, "Management of the Organic Fraction of Municipal Solid Waste in the Context of a Sustainable and Circular Model: Analysis of Trends in Latin America and the Caribbean," Int J Environ Res Public Health, vol. 19, no. 10, 2022, doi: 10.3390/ijerph19106041.

[2]       L. Mu, L. Zhang, K. Zhu, J. Ma, and A. Li, "Semi-continuous anaerobic digestion of extruded OFMSW: Process performance and energetics evaluation," Bioresour Technol, vol. 247, pp. 103-115, 2018, doi: 10.1016/j.biortech.2017.09.085.

How to cite: Becerra Quiroz, A. P., Solano Meza, J. K., Rodrigo-Clavero, M. E., and Rodrigo-Ilarri, J.: Modeling Anaerobic Digestion Processes to Treat the Organic Fraction of Municipal SolidWaste in a Megacity: A Comprehensive Approach to Sustainable Waste Management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19079, https://doi.org/10.5194/egusphere-egu24-19079, 2024.

Posters on site: Thu, 18 Apr, 16:15–18:00 | Hall X4

Display time: Thu, 18 Apr 14:00–Thu, 18 Apr 18:00
Chairpersons: Davide Bernasconi, Yikai Liu
X4.152
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EGU24-6002
Caterina Caviglia, Enrico Destefanis, Valentina Brombin, Maura Mancinelli, Annalisa Martucci, Costanza Bonadiman, and Alessandro Pavese

The fly ashes resulting from municipal solid waste incineration (MSWI FA) are classified as hazardous waste due to their high metal and soluble salt content, posing environmental risks upon reuse.
The CLEAN project, funded by the Ministry of the Environment and Protection of Land and Sea, introduced steam washing (SW) to reduce chloride and metal concentrations in FAs. This process transforms them into non-hazardous waste, suitable for stabilization, with ongoing investigations exploring the recovery of metals (Cr, Ni, Cu) aligning with the raw-secondary materials market.
Detailed elemental characterizations of solid matrices (pre- and post-SW) and liquid matrices (residual washing water, wastewater) employed X-ray fluorescence (XRF), X-ray diffraction (XRD), and inductively coupled plasma mass spectrometry (ICP-MS).
Results from a waste-to-energy plant in northern Italy indicate metals like Cr (300 mg/kg), Ni (65 mg/kg), Cu (1500 mg/kg), and Sb (1800 mg/kg) concentrating in the solid residue. After a 40% weight loss of FAs post-washing, there's an 80-90% increase in these elements per kg of ash. Residual washing water has high metal concentrations: 6000 mg/L Zn, 400 mg/L Pb, and 250 mg/L Cd, corresponding to approximately 15%, 10%, and 70% extraction from FAs (considering SW uses a 1.5-2.0 liquid-solid ratio).
Sequential extraction methods, variable pH release tests, and geochemical simulations trace metal species behavior to different speciation in FA. Many elements associate with mineralogical phases unstable at the treatment's pH (around 6), favoring mobilization (e.g., chlorides, hydroxides, carbonates, and surface adsorption).
While these chemical species pose challenges in FA, they can be valuable resources if extracted and recovered. SW yields two matrices suitable for metal recovery: a treated solid and a liquid one. For the solid matrix, increased heavy metal concentration per kg of FA favors effective extraction via targeted washing with diluted acid (e.g., HCl 2-3M), limiting reagent consumption. Analyses for the elemental characterization of wastewater are underway after absorption and recovery of metals by minerals like zeolites.

How to cite: Caviglia, C., Destefanis, E., Brombin, V., Mancinelli, M., Martucci, A., Bonadiman, C., and Pavese, A.: Sustainable Solutions for Incineration Byproducts: The CLEAN Project's Innovative Approach to Municipal Solid Waste Incineration Residue Management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6002, https://doi.org/10.5194/egusphere-egu24-6002, 2024.

X4.153
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EGU24-7365
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ECS
Hosub Lee, Seulki Jung, Jinsung An, and Kyoungphile Nam

In a spatially limited contaminated site, in situ synthesis of iron oxide would be an option for metal stabilization. We proposed the repetition of in situ iron oxide synthesis through additional simultaneous injection of iron oxide synthesizing solution, Fe(NO3)3, and NaOH to enhance the stability of heavy metals. In this study, iron oxide was repeatedly synthesized, and the behavior of immobilization of Cd, Zn, and As was investigated. Cd, Zn, and As were surface-adsorbed on the first synthesized iron oxide 69±0.97%, 38±1.6%, and 23±0.96%, respectively. The remaining metals were adsorbed into the ferrihydrite structure (i.e., incorporation). Repeating the synthesis resulted in reduced surface adsorption rates of Cd and Zn at 54±2.6% and 23±1.5%, respectively, while As adsorption remained constant at 23±0.54%. Meanwhile, the crystallinity of the second and third-synthesized iron oxides measured using X-ray diffraction (XRD) was similar to that of pure ferrihydrite. Encapsulation of the surface adsorbed metals occurred due to particle growth on pre-synthesized iron oxide by agglomeration on the surface. However, encapsulation of surface-adsorbed As was not observed, probably due to its inhibitory effect on ferrihydrite agglomeration. The incorporation and encapsulation of heavy metals were determined by scanning transmission electron microscopy (STEM). The zone axis [11¯0] fast Fourier transform (FFT) reveals that the interplaner lattice space (d-spacing) of the c-axis elongates by 0.001 – 0.012 nm compared to pure ferrihydrite. In addition, a common zone of axis of brighter spots was also found at multiple bulk sites of iron oxide of high-angle annular dark-field (HAADF) image, indicating metal incorporation within the iron oxide. The abundance of metals as an atomic ratio measured by TEM energy-dispersive X-ray spectroscopy (EDS) line-scanning from the edge to the bulk site of iron oxide showed encapsulation of metals by repetition. The metal abundance at the edge site decreases with additional synthesis due to an increase in the number of Fe in the surrounding area, while a constant abundance of stabilized metal from a single synthesis was consistently detected across the edge to the bulk site. However, As shows a constant abundance in both single and repetitive synthesis. The Fourier transform of Fe K-edge extended X-ray absorption fine structure spectroscopy (EXAFS) was also able to determine the incorporation of heavy metals within the iron oxide by the single synthesis. As expected, the number of neighboring second and third shell-ions increased and those radial distances were shortened by 0.01 – 0.03 Å are distinctively observed for Zn and As. Electron probe micro-analyzer (EMPA) analysis results indicate a lower relative metal concentration within the third-synthesized iron oxide structure than the first synthesis. This result exhibits repetitive synthesis induces agglomeration and aggregation of previously synthesized iron oxide further encapsulates surface-adsorbed metals which explains the reduction of surface-bound metals extractability with an increasing number of the iron oxide synthesis. The findings suggest that repeated synthesis of iron oxide can enhance the stabilization of heavy metals by encapsulating Cd and Zn, which were previously adsorbed on the iron oxide surface synthesized by a single application.

How to cite: Lee, H., Jung, S., An, J., and Nam, K.: Spectroscopic study on heavy metals stabilization by repetitive in situ iron oxide synthesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7365, https://doi.org/10.5194/egusphere-egu24-7365, 2024.

X4.154
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EGU24-16746
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Highlight
Rubén Forján, Álvaro Amado-Fierro, Teresa A. Centeno, Carlos A. López-Sánchez, Jose Luis R. Gallego, and Lorena Salgado

Hydrothermal carbonization (HTC) at temperatures of 150-250°C and self-generated pressures of 1−5 MPa is an efficient technology to convert wet biomass wastes into stable carbon-rich solids (hydrochars) with great potential for energy production/storage, soil amendment, sustainable construction, adsorption, catalysis, etc., within a circular economy framework.

The different composition of the biomass residues, the impact of the operating conditions and the diversity of the reactions that take place during the HTC process make the design of hydrochar production very challenging.

In this study, machine learning (ML) techniques enabled addressing the inherent complexity of interactions among diverse variables and accurately modeling their relationships in order to guide the hidrochar production and properties. Three algorithms, namely Multiple Linear Regression (MLR), Support Vector Machine (SVM), and Random Forest (RF), have been chosen and systematically compared in their ability to predict the variables that exert the most influence on the development of a stable hydrochar.

Analyses were accomplished on 93 representative samples of hydrochars derived from 12 radically different bio-wastes (out-of-use woods, apple bagasse, organic fraction from municipal solid waste, sewage sludge, digestate, etc.) subjected to HTC at 180, 200 and 230 °C for 2 and 4 h.

The modeling of four key performance indicators associated with production and quality of hydrochar, such as H/C and O/C atomic ratios, the calorific value (expressed as higher heating value, HHV) and yield have been developed. The approach relies on the comprehensive analysis of a number of dependent variables categorized into six main groups: set-up parameters, operational parameters, hydrochar characterization (proximate and ultimate analysis) and thermal properties under inert (N2), oxidative (air) and reactive (CO2) atmospheres. Each category addresses specific aspects of the HTC process and/or hydrochar formation and its properties.

The results show that SVM achieves a better goodness of fit for H/C (R2=0.88), while RF for O/C (R2=0.92), HHV (R2=0.96), and yield (R2 = 0.88) variables, both of them no-parametric algorithms. Regarding the dependent variables, the most influential categories in predicting H/C are those associated with hydrochar characterization and combustion thermogram parameters, being the variable with the greatest importance, the fixed carbon, associated to the solid carbon that remains in char after devolatilization. For O/C, those related to hydrochar characteristics and pyrolysis thermogram parameters have a relevant role. The HHV is determined by parameters of hydrochar characterization and gasification thermograms, being the most important variables the fixed carbon, associated to the solid carbon that remains in char after devolatilization, and the reactivity when 1000 °C reached and 30 and 60 minutes passed. The results obtained for yield indicate that the most important category is operational parameters, being the variables with the greatest significance, the energy, indicative of energetical harvesting potential, and densification ratio, indicative of energetical improvement.

This investigation belongs to the European Union's Horizon 2020 research and innovation program, under grant agreement No. 101006656 (GICO Project), and also to the Agroalimentación Cero Emisiones project funded by Misiones Científicas del Principado de Asturias 2022 AYUD/2022/24227 (Spain).

How to cite: Forján, R., Amado-Fierro, Á., Centeno, T. A., López-Sánchez, C. A., R. Gallego, J. L., and Salgado, L.: Comprehensive Analysis and Machine Learning Modeling of Hydrochar Characteristics: Optimizing Production Variables and Predictive Insights, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16746, https://doi.org/10.5194/egusphere-egu24-16746, 2024.

X4.155
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EGU24-18228
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ECS
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Highlight
Alessia Nannoni, Patrick Byrne, Patrizia Onnis, Alex L Riley, Catherine Gandy, Ian Burke, Karen Hudson-Edwards, Will Mayes, and Adam Jarvis

Climate change is expected to significantly affect the release of toxic elements from legacy waste landfills across coastal areas because it will enhance severe flooding, erosion, and extreme wetting-drying cycles. The UK’s industrial past resulted in a wide range of legacy wastes deposited in estuarine and coastal settings, for a total of 2550 sites. In this perspective, a NERC project is ongoing to provide a national-scale assessment of geochemistry and mobility of these wastes, which is necessary to establish environmental and ecological risks and to prioritize sites for management interventions. In the project framework, a mesocosm experiment was carried out to investigate the leaching processes that can occur in different types of legacy wastes (LW) disposed across the UK coasts. The experiment was designed to study how wetting and drying cycles affects the release of pollutants in the coastal areas. Four sites were selected, each one for a different type of LW: colliery (L), landfill municipal wastes (CB), metal smelter (CP), and mining-impacted sediments (HE). These four sites represent the range of LW geochemistry encountered across the UK. Each wetting/drying cycle (WDC) lasted 2 weeks. Artificial rainwater was used to inundate the columns. Water samples were collected weekly for Dissolved Organic Carbon (DOC), major ions and metals. EC, Eh, DO, and DOC showed a great variability both at inter- and intra-sites: the L samples were the most acid ones (pH = 3.3 – 5.1), whereas the other sites showed pH values ranging from 6.0 to 8.7. HE samples showed the largest variation ranges for EC and DOC (409 – 109000 µS/cm and 8.3 – 405.8 mg/l, respectively), whereas the CP ones showed the narrowest ranges for both parameters (176 – 592 µS/cm and 0.2 – 248.1 mg/l, respectively). The maximum variation for EC and pH occurred after the first WDC for all the sites but CP, which showed a progressive decrease in both parameters throughout the experiment. DO, Eh, and DOC varied more irregularly for all sites. For each site, Control samples showed wider ranges of variation than those that experienced the WDC but the trends were similar for both control and non-control ones. These preliminary data, together with trace metal data, suggest that leaching processes are more likely to be efficient at the end of prolonged dry periods when heavy storms occur. Extreme climate conditions are expected to become more frequent in the near future, therefore a proper management is mandatory to reduce the risk posed by the coastal legacy wastes.

How to cite: Nannoni, A., Byrne, P., Onnis, P., Riley, A. L., Gandy, C., Burke, I., Hudson-Edwards, K., Mayes, W., and Jarvis, A.: Impacts of climate-driven wetting and drying on mobilization of trace metals in legacy coastal wastes in the United Kingdom, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18228, https://doi.org/10.5194/egusphere-egu24-18228, 2024.

X4.156
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EGU24-21199
Silvia Patricia Barragan Mantilla, Raquel Ortiz, Gabriel Gascó, Laura Sánchez, Patricia Almendros, and Ana Méndez

The demand for metals is increasing, so the need of looking for greener alternatives to obtain them [1]. Techniques such as hydrometallurgy have been thoroughly studied to obtain better metal recoveries from different feedstocks, including low-grade ores, mine tailings, and spent batteries, which are normally difficult and expensive to treat [2]. This study focused on the implementation of an amino acid to promote metal recovery, particularly Zn from spent batteries, and its possible application in agriculture. For the leaching, we used a ratio of glycine (8/1), hydrogen peroxide, and sodium hydroxide (to adjust pH) at room temperature, 200 rpm, and different pH values (7.0, 8.0, 9.0, 10.0, 11.0, and 12.0). At 0.5, 1, 2, 4, 6, 22, and 24 h, we measured pH and potential and took aliquots of each sample. Subsequently, samples were characterized by atomic absorption spectrometry and processed. According to the results, the best recoveries were achieved at lower pH values. Although the results obtained are not on par with those of acid leaching systems, they provide important insights into factors that may affect recovery rates (i.e., type of material, pH, glycine/oxidant agent) [3,4], which leads to the development of strategies to optimize them.

Acknowledgments: This research has been funded by the Ministerio de Ciencia e Innovación y Universidades (MCIU), Agencia Estatal de Investigación (AEI), and European Union “NextGenerationEU” with grant number TED2021-131198B-I00 “GREEN-AGRO-REC”.

[1] Henckens, M. L. C. M., Driessen, P. P. J., & Worrell, E. (2014). Metal scarcity and sustainability, analyzing the necessity to reduce the extraction of scarce metals. Resources, Conservation and Recycling, 93, 1–8. https://doi.org/10.1016/j.resconrec.2014.09.012

[2] Mohanraj, G. T., Rahman, M. R., Arya, S. B., Barman, R., Krishnendu, P., & Singh Meena, S. (2022). Characterization study and recovery of copper from low-grade copper ore through hydrometallurgical route. Advanced Powder Technology, 33(1). https://doi.org/10.1016/j.apt.2021.12.001

[3] Shin, D., Ahn, J., & Lee, J. (2019). Kinetic study of copper leaching from chalcopyrite concentrate in alkaline glycine solution. Hydrometallurgy, 183, 71–78. https://doi.org/10.1016/j.hydromet.2018.10.021

[4] Tanda, B. C., Eksteen, J. J., & Oraby, E. A. (2017). An investigation into the leaching behavior of copper oxide minerals in aqueous alkaline glycine solutions. Hydrometallurgy, 167, 153–162. https://doi.org/10.1016/j.hydromet.2016.11.011

How to cite: Barragan Mantilla, S. P., Ortiz, R., Gascó, G., Sánchez, L., Almendros, P., and Méndez, A.: Use of sustainable extractants for the Zn recovery from spentbatteries for agricultural purposes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21199, https://doi.org/10.5194/egusphere-egu24-21199, 2024.

X4.157
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EGU24-21201
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Highlight
Raquel Ortiz Castillo, Silvia Patricia Barragán Mantill, Gabriel Gascó, Ana Méndez, Laura Sánchez, and Patricia Almendros

The use of highly effective sources of zinc in agriculture is necessary to achieve adequate crop quality and to avoid potential environmental hazards [1]. The use of synthetic chelating agents can lead to environmental risks such as contamination by leaching into aquifers [2]. There is currently a growing interest in the use of environmentally friendly zinc sources as an alternative to traditional ones [3]. This study focused on the evaluation of the leaching capacity of different Zn sources extracted from spent batteries with H2SO4 2M, H2SO4 0.25M or environmentally friendly complexes (glycine or citrate) in comparison with the traditional ZnSO4 source. Columns of 15 cm height and 1.5 cm diameter with 25 grams of washed sand were used for this. The treatment to carry 5 mg of Zn was added to each column and covered with another 5 g of sand. A flow of 10 ml/h of 0.01 M CaCl2 solution was added from the top of the columns. The leachates were collected in 20 ml portions until a total of 400 ml. The result showed distinct trends for the added treatments. The evolution of accumulated leached Zn for each of the treatments was fitted to the logistic model. The Zn-H2SO4 0.25M treatment achieved the highest percentages of total leached Zn at 400mL, accounting for more than 98% of the leached Zn with respect to the total Zn added to the columns. This percentage was statistically higher (P˂0.05) than the rest of the treatments, among which there were no significant differences in the total leached Zn, which reached percentages of between 72.68 and 77.12% (Zn-citrate and ZnSO4, respectively).

Acknowledgments: This research has been funded by the Ministerio de Ciencia e Innovación y Universidades (MCIU), Agencia  Estatal de Investigación (AEI), and European  Union  “NextGenerationEU”  with grant number  TED2021-131198B-I00 “GREEN-AGRO-REC”.

1.  Alloway, B.J. Zinc in Soils and Crop Nutrition; Second edi.; International Zinc Association Brussels, Belgium: Brussels, Belgium and Paris, France, 2008;
2. Chandrika, K.S.V.P.; Patra, D.; Yadav, P.; Qureshi, A.A.; Gopalan, B. Metal Citrate Nanoparticles: A Robust Water-Soluble Plant Micronutrient Source. RSC Adv. 2021, 11, 20370–20379, doi:10.1039/d1ra02907j.
3. Ortiz, R.; Gascó, G.; Méndez, A.; Sanchez-Martín, L.; Obrador, A.; Almendros, P. Comparative Study of Traditional and
Environmentally Friendly Zinc Sources Applied in Alkaline Fluvisol Soil: Lettuce Biofortification and Soil Zinc Status. Agronomy 2023, 13, 4–15, doi:10.3390/agronomy13123014.

How to cite: Ortiz Castillo, R., Barragán Mantill, S. P., Gascó, G., Méndez, A., Sánchez, L., and Almendros, P.: Zinc leaching potential of environmentally friendly zinc sources obtained from spent batteries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21201, https://doi.org/10.5194/egusphere-egu24-21201, 2024.

Posters virtual: Thu, 18 Apr, 14:00–15:45 | vHall X4

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 18:00
Chairpersons: Yikai Liu, Davide Bernasconi
vX4.45
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EGU24-3031
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ECS
Preparation of New Copper Smelting Slag-based Mine Backfill Material and Investigation of its Mechanical Properties
(withdrawn after no-show)
Minggui Jiang, Wei Sun, Kaifang Lu, and Tong Gao
vX4.46
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EGU24-3131
Determination of mechanical, flowability, and microstructural properties of cemented tailings backfill containing rice straw
(withdrawn after no-show)
Xin Chen and Zeyu Li
vX4.47
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EGU24-22554
Microstructure and mechanical properties of sustainable cemented-paste backfill materials with the substitution of alkali-activated rice husk ash
(withdrawn after no-show)
Bin Liu, Qinli Zhang, Yan Feng, and Daolin Wang
vX4.48
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EGU24-5203
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ECS
Micro-mechanism on strength development and failure mode of cemented ultra-fine tailing backfill: Influence of binder
(withdrawn after no-show)
Aiping Cheng
vX4.49
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EGU24-22556
Xinyi Yuan, Chao Zhang, and Zian Song

Reducing the substantial carbon dioxide emissions from mining activities is essential for establishing environmentally friendly mines and achieving carbon neutrality in the mining industry. This study introduces a practical approach for reducing carbon dioxide emissions in underground mining by leveraging shotcrete, a widely used material in mining, as a carrier for carbon mineral sequestration. Additionally, to further mitigate the overall carbon footprint related to the shotcrete preparation, we enhanced the carbonation process by utilizing bacteria and incorporating solid waste materials as ordinary Portland cement substitutes (mainly yellow phosphorus slag and coal gasification slag). Our research reveals that shotcrete containing bacteria microorganisms exhibits significantly enhanced carbonation rates compared to conventional shotcrete. Specifically, it absorbs approximately 0.76 kgCO2 per square meter within a span of 14 days. Moreover, the substitution of solid waste materials fixed with bacteria not only enhances the mechanical performance of the shotcrete but also further augments the bacterial carbonation ability. Characterization techniques, such as XRD and SEM/EDS, reveal the presence of captured carbon dioxide in the form of calcite, pyrrhotite, and magnesite, resulting in a denser cementitious matrix and improved mechanical properties.

How to cite: Yuan, X., Zhang, C., and Song, Z.: Mechanical properties and carbon sequestration potential of MICP-based shotcrete partially substituted with industrial solid waste, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22556, https://doi.org/10.5194/egusphere-egu24-22556, 2024.