Residual Material Research Articles

Mechanism analysis on carbon-ash separation of coal gasification fine slag by high internal phase emulsion collector

ABSTRACT Coal gasification slag is a solid waste produced in modern coal chemical industry, its mixed characteristics of residual carbon and ash materials restrict its resource utilization. This study focused on improving the flotation effect of coal gasification slag and reducing the consumption of flotation reagents, a water in oil type high internal phase emulsion collector was prepared, and the microstructure, rheology, stability, particle size and other characteristics of the emulsion collector were analyzed. By comparing with the flotation effect of conventional kerosene collector, when the amount of organic liquid is basically equal, the ash content of the tailings increased by 4.02%, the yield of concentrate increased by 9.79% and the recovery of combustible matter increased by 11.11%. When the combustible matter recovery is similar, the emulsion collector can save 13.40% of kerosene. The flotation kinetics test shows that the emulsion collector can significantly improve the flotation speed. By analyzing the flocculating ability of emulsion collectors, emulsion collectors can significantly improve the flocculating ability of particles, thereby improving the flotation effect. The research results have certain guiding significance for improving the flotation efficiency of coal gasification slag.

Low-cost nano biochar: a sustainable approach for drought stress mitigation in faba bean (Vicia faba L.)

This study tends to reach some objectives of the sustainable development goals, which call for responsible consumption and production and climate action. Long-term global food security is affected by drought and the optimal use of water in agricultural areas under climate change scenarios. Our approach aims to amend soil for cultivation under drought stress and improve plant growth to contribute to food security. In this context, a biochar was prepared from peanut shell and thoroughly examined as a soil enhancer for broad bean cultivation during drought stress. The produced biochar exhibited 0.307 g cm−3 bulk density, 9.6 cmol kg−1 cation exchange capacity, −15.5 mV zeta potential, and an average diameter of 21.86 nm. Surprisingly, the application of biochar increased soil water holding capacity and organic matter by 66% and 220%, respectively. Moreover, its application under drought improved plant growth as indicated by stem height, leaf area index, pod number/plant, pod weight, protein level, chlorophyll content, nutrient levels in leaves, and reduced lipid peroxidation and electrolyte leakage. The principal component and factorial analysis of the current study demonstrated correlations between the physiological response of faba bean plants and soil physiochemical parameters after the application of peanut shell-derived biochar. This study presents promising nano biochar that could be an effective sustainable practice for disposing residual materials.

Mechanical Characterization of Sustainable Mortars with Recycled Aggregates from Construction and Demolition Wastes: An Experimental Investigation

The use of recycled aggregates in the production of concrete and mortar represents a sustainable way to reintroduce these constituents—which are typically treated as waste and disposed of—in the production chain, providing new value to potentially polluting materials. The effect of recycled aggregates has been widely studied in the production of concrete due to the directions of National Standards in Italy; however, their role in the manufacturing of mortar must be investigated further due to the high variability that can be observed in the literature. In particular, the aim of this paper is the mechanical characterization of sustainable mortars defined by different mix designs and different binders, in which the aggregates are gradually replaced by a recycled sand obtained from the grinding of construction and demolition wastes, which could include old concrete, clay bricks, and minimal amounts of other kinds of residual materials. This investigation is carried out through experimentation, taking into account four different mortar compositions defined by an increasing percentage of recycled constituents. Virgin aggregates are also studied for the sake of comparison. The results, accomplished through a three-point bending test and an unconfined compression test, show that it is still possible to maintain acceptable mechanical properties by using these wastes as aggregates in spite of a decrease in the analyzed values. In general, the mean reductions with respect to the use of natural aggregates are about 30–40% and 35–55%, respectively, for compressive and flexural strengths. It should be highlighted that some experimental sets provide a maximum reduction of 70–80%, but the results are still within the limitations of the standards. This aspect can be considered to be a good compromise since the production of this sustainable construction material can represent a solution that is able to reduce the extreme exploitation of natural resources, the pressure on landfills, and the consumption of energy, which are related to the construction industry.

Supply security beyond mines and scrap recycling: valorization potential of metallurgical residues.

In the context of the European Critical Raw Materials Act, this work attempts to demonstrate the potential of residual material flows from non-ferrous metallurgy and their possible contribution to the supply security of metals by locally available new secondary resources, assuming technically and economically viable processing. Based on the aluminium, zinc, copper and lead industries, the resulting waste streams are discussed and, in particular, the complex process consisting of physical, chemical and metallurgical steps is described. Their diversity, be it slags, dusts or even sludges, has a wide variety of morphologies and compositions due to the process of generation. In the past, many concepts for reprocessing were investigated, but the goal was usually only the recovery of one target element or to avoid landfilling by using it, for example, as a building material, whereby the metals contained are completely lost. If the target is the extraction of valuables, the required interdisciplinary process development must be based on an in-depth characterization to understand the behaviour of metals and trace elements in possible extraction steps and also to develop suitable strategies for influencing the behaviour of target elements with the aim of extraction. This starts with an in-depth comprehension of the formation process, which is the subject of this article and has a direct influence on the composition and morphology of the materials, thus forming the basis for understanding the behaviour in potential recycling processes. Furthermore, typical compositions of the residual material streams, sources and, if available, quantities are shown and, in summary, an attempt is made to evaluate the materials in a SWOT analysis and to address the challenges in developing extraction steps for processing. While mine tailings are mostly found outside of Europe, the potential of the residual materials from metallurgy is local due to the processing of the concentrates in Europe. This leads to several potential advantages in a possible reprocessing, such as no or shorter transport routes, which is linked to lower quantity of emissions, defined volume and known composition, no geopolitical risk, conservation of primary resources, and increasing Europe's sustainability through a more comprehensive use of the raw materials.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Is Apical Enlargement with Single Reciprocating Instruments the Key to Success in Endodontic Retreatment?

Modern endodontics has provided significant advancements, particularly in the treatment and retreatment of root canals. However, the complete removal of obturation material during retreatment remains a challenge, especially in the apical third of root canals, where complex anatomy imposes limitations. This study aimed to evaluate the effectiveness of using WaveOne Gold reciprocating instruments of different diameters and kinematics (brushing motion and pecking motion) for removing obturation material from root canals during retreatment, with a particular focus on the apical third. Thirty human maxillary molars with separate roots were selected and divided into four groups. Root canals were prepared and obturated using different WaveOne Gold instruments (Primary and Medium) and then retreated with larger diameter instruments using different kinematics. The removal of obturation material was evaluated through cone beam computed tomography (CBCT). The results were statistically analyzed using ANOVA and logistic regression. Statistical analysis revealed no significant differences between the groups regarding the type of instrument or kinematics applied. Residual obturation material was observed in approximately 60% of the samples, regardless of instrument diameter or kinematics used, indicating that complete removal of obturation material from the apical portion of root canals remains a substantial challenge. The use of larger diameter instruments, such as the WaveOne Gold Medium, and the application of brushing motion kinematics did not prove significantly more effective in removing obturation material compared to smaller diameter instruments. These findings highlight the need to explore new approaches and technologies to optimize obturation material removal, especially in complex anatomical regions like the apical third of root canals.

Effect of Tissue Fragments Remain in the Karman Cannula on the Histopathological Diagnosis of Abnormal Uterine Bleeding.

The aim of this study was to perform histopathological analysis of residual material in the cannula by endometrial sampling using a Carmen injector, and to compare the results. The study was conducted in the Department of Gynaecology, Mardin Training and Research Hospital, Artuklu/Mardin, Turkiye, from December 2021 to June 2022. The study group consisted of 104 patients who presented to the outpatient clinic with complaints of abnormal uterine bleeding. Endometrial curettage material was collected from all patients using a Carmen injector. The collected material was discharged into the pathology container (Group 1). Subsequently, the residual material remaining in the injector was placed in a separate pathology container (Group 2). Specimens were sent to the pathology laboratory with buffered formol. The pathological evaluation was performed by the same pathologist without revealing the patients' names. Comparative histopathological results of the patients in Group 1 and Group 2 were found to be fully compatible in 64.4% of the patients. In 35.6% of the patients, the histopathological results were different from each other between Group 1 and Group 2. Pathological results were different from each other in 21.2% of patients with incompatible pathology results. In Group 1, 16.7% of the patients were over-diagnosed, while 7.7% of the patients were over-diagnosed in Group 2. It would be beneficial to carefully remove the material remaining in the cannula and send it for pathological examination as it may affect the histopathological results. Key Words: Abnormal uterine bleeding, Probe curettage, Karman cannula, Histopathological evaluation.

Can hydrogen be generated by UV- photodegradation of biomass residues in water media?

The photoinduced processes can be promising routes for hydrogen generation. This study explores hydrogen production through the non-catalyzed photodegradation of various biomass materials, a process that remains largely understudied compared to the catalyzed ones, i.e., photoreforming. Using as precursor almond shell (AS), a lignocellulosic biomass residue, various solid and liquid materials obtained from it were tested as substrates. These materials were obtained through different pretreatment methods including grinding, milling, pyrolysis, and hydrothermal carbonization (HTC), and compared with milled cellulose (MC). Photodegradation tests, conducted in aqueous media under UV light, revealed that hydrogen production strongly depends on the structural and compositional features of the substrates. Among the solid samples, ground almond shell (GAS) and milled cellulose (MC) showed promising hydrogen yields. However, the liquid residue from the HTC process using diluted phosphoric acid (HMAS-L2), which is rich in simple organic acids, stood out, delivering the highest hydrogen production across all the substrates, and reaching an impressive value of 105 μmol of H2 in 5 h of reaction. Attention was also given to the production of other gases, particularly carbon dioxide and methane, as a result of the photodegradation. CO2 production occurred for all the substrates. PMAS (the pyrolyzed milled almond shell) and, specifically, HMAS-L2 generated detectable amounts of CH4 (5 and 22 μmol, respectively).The H2/CO2 ratios reached 0.66 for MC and 0.44 for HMAS-L2, highlighting the interest in evaluating the non-catalyzed biomass photodegradation as a preliminary step for future photoreforming studies. These findings enhance our understanding of biomass-based hydrogen generation and open new avenues for exploring non-catalyzed photoinduced processes.

Machine learning powered predictive modelling of complex residual stress for nuclear fusion reactor design

Fusion In-vessel components, assembled and maintained using laser welding, one of the most promising techniques, exhibit complex distributions of residual stress, microstructures, and material properties. These residual stresses can compromise structural integrity and lifespan of critical components. Although using advanced experimental measurements can evaluate the residual stress for individual case, extending the measurements to massive number of components are costly and time-consuming. Traditional machine learning (ML) models struggle to account for the heterogeneity and anisotropy of these stress distributions. Here, we develop a novel ML framework based on the Eurofer97 steel, the structural material for in-vessel components. The ML framework is trained on high-resolution residual stress data derived from recently-developed evaluation techniques. Combining with microstructures, the model enables prediction of heterogenous and anisotropic residual stress distribution. It successfully predicts the compressive residual stress in fusion zone (∼−200 MPa) balanced by tensile residual stress in heat affected zone (∼300 MPa), aligning closely with experimental results with the R-squared value of 0.989 and the mean square error of 10−4. Unlike experiments that take hours, the ML model provides predictions within seconds. It offers valuable insights into residual stress prediction for various joints, enhancing the reliability and lifetime prediction of in-vessel components.

High-temperature thermochemical conversion of iron ore tailings into diopside and akermanite-based composite materials

Iron ore tailings (IOTs), the residue materials generated during iron ore processing, pose environmental challenges due to their massive volume and potential impact on ecosystems. This study proposes a sustainable approach to manage and utilize this solid waste by converting it into value-added composite materials through high-temperature thermochemical reactions. Experiments are conducted in a tubular reactor at various reaction temperatures and times, and the resulting product samples are comprehensively characterized to elucidate their chemical compositional, physical, microstructural, thermal, and electrical properties. The results reveal that at optimal reaction temperatures (1230–1260 °C) and reaction times (20–120 min), the synthesized product is predominantly composed of diopside (CaMgSi2O6) and akermanite (Ca2MgSi2O7). Additionally, we demonstrate that the product can be diopside-rich or akermanite-rich when blending silica and MgO powders into the IOTs to control the starting material composition, opening a promising avenue for large-scale sustainable utilization of industrial solid waste.

Two Stage Sinus Lifting Using Nanohydroxyapatite Particles Versus Deproteinized Bovine Bone: Randomized Clinical Trial.

Sinus floor elevation is one of the predictable techniques for augmentation of vertically deficient posterior maxillary alveolar ridges. Several biomaterials were reported to be successful for sinus augmentation, including xenografts and hydroxyapatite. The aim of this study was to compare the quality and quantity of generated bone using xenografts versus nanohydroxyapatite in sinus augmentation. Twenty-four patients/sinuses were randomly assigned into two groups; in the control group, patients underwent sinus floor elevation and augmentation using deproteinized bovine bone (DBB), whereas in the study group, the sinus was augmented using nanohydroxy-apatite bone (NHA). For each patient, the amount of bone height was assessed preoperatively, immediately postoperatively, and 6 months postoperatively. Furthermore, the quality of the newly formed bone was assessed via histological and histomorphometric analyses after 6 months postoperatively. Both biomaterials showed a good level of consolidation. In the study group, the mean bone height after 6 months was 11.72 ± 1.24 compared to 12.01 ± 1.16 mm in the control group which was not statistically significant (p > 0.05). The mean bone area percent of newly formed bone was 29.84% ± 6.7% for NHA group and 34.73 ± 7.9 for DBB group. Moreover, the mean percent of residual grafting material was 32.43% ± 11.53% for NHA group compared to 30.43% ± 8.27% for DBB group. Histologically, there was no significant difference between both groups regarding different parameters (p > 0.05). The two-stage sinus floor augmentation using NHA and DBB revealed no statistically significant difference regarding both the quality and the quantity of the regenerated bone. Studies with larger samples and longer follow up are recommended. ClinicalTrials.gov identifier: NCT03184857.

Green fabrication of cost-effective and sustainable nanoporous carbons for efficient hydrogen storage and CO2/H2 separation

In this study, sustainable nanoporous carbon materials that are efficient, renewable, cost-effective and adaptable were developed. These microporous feature carbon adsorbents were synthesized utilizing a straightforward and efficient method. Plum stones are residual fruit materials that offer a financially feasible and sustainable carbon source with exceptional porosity and desirable elemental composition. The plum stones underwent carbonization and were subsequently chemically modified with polyaniline nanofibers and then subjected to chemical activation using different activating agents. This yielded sustainable nanoporous carbon with a high degree of porosity, in conjunction with doping with precious high electron density elements such as O, N and S. The sustainable nanoporous carbons that have been developed exhibits exceptional microporosity, with BET-SSA of 1705 m2 g−1 and a pore volume of 0.726 cm3 g−1, besides, the dominance of ultramicropores of 0.6 nm size. This in addition to convenient doping of oxygen, nitrogen and sulfur elements which are crucial for H2 uptake. The developed nanoporous carbon demonstrated highly promising capabilities for storing H2 molecules at cryogenic and ambient temperatures. The sustainable adsorbent achieved hydrogen storage capacities of 4.63 and 0.45 wt% at 77, 296 K, and a pressure of 40 and 80 bar, respectively. This H2 storage capacity at RT is often regarded as one of the highest reported in the literature for nanoporous adsorbents. Moreover, study investigated the separation selectivity of developed adsorbents for CO2/H2 based on uptake ratio at 30 bar and RT. The results demonstrated a significant separation selectivity reaching a value of 382.5 for the CO2/H2, which is regarded as one of the most elevated values documented in the existing literature for nanoporous carbon materials. Thus, the presented sustainable nanoporous materials have shown great promise for hydrogen storage, pre-combustion CO2 capture and H2 purification applications at ambient temperature.

EXCAVATIONS IN THE ANCIENT THEATRE OF SPARTA, 2008

This article presents the results of the 2008 excavation in the ancient theatre of Sparta conducted by the British School at Athens and the Ephorate of Antiquities of Laconia. Focused on the west side of the cavea, work aimed to locate the southern edge of the Late Antique settlement between the theatre and the sanctuary of Athena Chalkioikos; to establish the northern limits of the Late Antique settlement over the former orchestra; and to establish a more precise ceramic characterisation and chronology for the Early–Middle Byzantine period in Sparta. The area between settlement clusters on the acropolis and over the former orchestra was essentially open, with just a Byzantine terrace wall and path recorded. In the north-west part of the former cavea, a tomb built in the late eighth or early ninth century AD was used at least until the late thirteenth century for the burial of c. 29 individuals. This article presents the first results of a bioarchaeological study of the human remains, and studies of Byzantine pottery from the tomb interior and from the backfill of the pit in which the tomb was built (the latter including a notable quantity of Early Byzantine domestic ware). The 2008 findings are set in the larger context of research on post-antique phases in the theatre (drawing on the British School at Athens Archive) and on the material culture and urban topography of Byzantine Sparta. Almost all excavated contexts contained residual material of all periods. The article concludes with short catalogues of material which pre-dates the construction of the theatre and of inscriptions of all periods.

A Novel Approach for Predicting the Mid–Long-Term Radiation Dose in the Case of a Hypothetical STSBO Nuclear Accident for an Operating Nuclear Power Plant

Four severe nuclear accident scenarios have been identified for operating nuclear power plants (ONPPs). However, there is a research gap in predicting the mid–long-term radiation doses for these scenarios. This study aims to address this gap by proposing a novel approach for predicting the mid–long-term radiation dose in the case of a hypothetical short-term station blackout (STSBO) scenario, one of the aforementioned scenarios. Firstly, the Weather Research and Forecasting (WRF) model was coupled with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) (WRF-HYSPLIT) model to establish an atmospheric transport and diffusion model for airborne radionuclides, and the regularity of the atmospheric transport and diffusion for the airborne radionuclides was determined. Subsequently, the Residual Radioactive Material Guidelines (RESRAD) OFFSITE (RESRAD-OFFSITE) code was utilized to establish a radiation dose model for predicting the mid–long-term radiation dose resulting from the airborne radionuclides, and the evolution of the mid–long-term radiation dose was analyzed. Finally, the proposed approach was applied to an ONPP, and the results were used to predict the mid–long-term public radiation dose. The results indicated that the total radiation dose would be lower than the dose limit recommended by the International Commission on Radiological Protection (1 mSv/yr) from the second month to the 100th year after the hypothetical STSBO nuclear accident, and the total radiation dose would decrease slowly over time. Recommendations are made for offsite emergency response measures. These research findings can assist ONPPs in analyzing their environmental impacts in the event of an STSBO scenario.

Fibre post removal using ultrasonic tips: A comparative invitro study using different protocols.

This study evaluated the glass fibre post (GFP) removal using three different protocols with ultrasonic tips. Thirty-six extracted single-rooted teeth were endodontically treated and cemented with a 10-mm GFP. Three protocols were used for GFP removal: 20 s activated with cooling, 20 s activated without cooling and 40 s activated without cooling. The removal time and temperature increase on the external root surface were recorded. The amount of residual material and the volume of dentin loss were assessed using micro-computed tomography. Data were analysed using ANOVA with a 5% significance level. The removal time and the amount of residual material were not affected by the protocol. There was no difference in temperature increase between the 20-s groups. The 40s activated without cooling produced the highest temperatures, especially in the apical region, and greater dentin loss. It is not advisable to use the ultrasonic insert continuously for more than 20 s.

Sustainability and Environmental Performance in Selective Collection of Residual Materials: Impact of Modulating Citizen Participation Through Policy and Incentive Implementation

The effective management of urban waste represents a growing challenge in the face of demographic evolution and increased consumption. This study explores the impacts of municipal strategic decisions on household waste management behaviours and sustainability performance outcomes through agent-based modelling. Using data from Gatineau and Beaconsfield in Quebec, Canada, the model is calibrated and validated to represent diverse urban contexts. Our analysis demonstrates that reducing collection frequency leads to notable increases in participation rates, reaching 78.2 ± 5.1% for collections every two weeks and 96.5 ± 8.3% for collections every five weeks. While this reduction improves bin filling levels, it concurrently decreases the recovery of recyclable materials by 2.8% and 19.5%, significantly undermining the environmental benefits of the recycling program. These findings highlight a complex interplay between collection frequency, citizen participation behaviour, waste stream characteristics, and overall environmental performance. While reducing collection frequency initially appears beneficial, it leads to operational challenges and increased CO2 emissions due to reduced material recovery. The research emphasises the need for tailored holistic waste management strategies that optimise performance outcomes while minimising environmental impacts. By understanding these dynamics, municipalities can develop more effective waste management policies that promote sustainability.

A novel tapered quartz tuning fork-based laser spectroscopy sensing

A novel tapered quartz tuning fork (QTF) was designed to enhance its stress magnitude and charge distribution in QTF-based laser spectroscopy, which had a low resonant frequency of 7.83 kHz and a wide fork gap for long energy accumulation time and easy optical alignment. Compared to the reported rectangular QTF, this tapered QTF transfers the maximum stress position from the root to the middle to improve its sensing performance. Furthermore, the unique design eliminates the 90° right angles typically found in standard QTFs, which often lead to undesired “webs” and “facets” during the etching process. This design minimizes performance degradation by reducing the presence of residual unexpected materials. QTF-based laser spectroscopy of quartz-enhanced photoacoustic spectroscopy (QEPAS) and light-induced thermoelastic spectroscopy (LITES) were adopted to verify its performance. Compared with the widely used standard QTF, the total surface charge of the tapered QTF was improved 5.08 times and 5.69 times in QEPAS and LITES simulations, respectively. Experiments revealed that this tapered QTF-based QEPAS sensor had a 3.02 times improvement in signal-to-noise-ratio (SNR) compared to the standard QTF-based system. Adding an acoustic micro-resonator to this tapered QTF-based QEPAS sensor improved the signal level by 97.20 times. The minimum detection limit (MDL) for acetylene (C2H2) detection was determined to be 16.45 ppbv. In the LITES technique, compared to the standard QTF, this tapered QTF-based sensor had a 3.60 times improvement in SNR. The MDL for C2H2 detection was determined to be 146.39 ppbv.

Comparative Histological Analysis of Dentine-Derived Tooth Grafts in Maxillary vs Mandibular Socket Preservation: A Retrospective Study of 178 Cases.

(1) Background: In recent years, there has been a growing interest in tooth-derived materials as valuable alternatives to synthetic biomaterials for preventing alveolar ridge dimensional changes. This study aimed to evaluate the histological and clinical differences between alveolar ridge preservation procedures in the maxilla and mandible using demineralized dentin treated with Tooth Transformer®. (2) Methods: A total of 178 patients in good general health were enrolled, with 187 post-extractive sockets lacking buccal and/or palatal bone walls. Alveolar socket preservation procedures and histological evaluations were performed. The sites were divided into two groups: Group A (99 mandibular samples) and Group B (108 maxillary samples). After 5 months (±1 month), single bone biopsies were performed for histologic and histomorphometric analysis. (3) Results: Clinical outcomes demonstrated a good healing of hard and soft tissues with an effective maintenance of bone architecture in both groups. Histomorphometric analysis revealed a total bone volume of 50.33% (±14.86) in Group A compared to 43.53% (±12.73) in Group B. The vital new bone volume was 40.59% (±19.90) in Group A versus 29.70% (±17.68) in Group B, with residual graft dentin material volume at 7.95% (±9.85) in Group A compared to 6.75% (±9.62) in Group B. (4) Conclusions: These results indicate that tooth-derived material supports hard tissue reconstruction by following the structure of the surrounding bone tissue. A 6.8% difference observed between the maxilla and mandible reflects the inherent disparities in natural bone structures in these regions. This suggests that the bone regeneration process after tooth extraction adheres to an anatomical functional pattern that reflects the specific bone characteristics of each area, thus contributing to the preservation of the morphology and functionality of the surrounding bone tissue.

Potassium Hydroxide Extraction of Polyphenols from Olive Leaves: Effect on Color and Acrylamide Formation in Black Ripe Olives

Olive leaves are generated in large quantities in olive oil and table olive factories. This waste is currently used for multiple purposes, one of them being the extraction of bioactive substances, in particular phenolic compounds. The aims of this study were (i) to obtain a new polyphenolic extract from potassium hydroxide (KOH) -treated olive leaves; and (ii) to reduce acrylamide formation in black olives by using this extract. The results showed that olive leaves and leafless branches of the Manzanilla cultivar treated with 10 g/L KOH provide a solution that, concentrated under vacuum, had >6000 mg/L hydroxytyrosol and >2000 mg/L of hydroxytyrosol 4-glucoside. Moreover, the residual material generated after the treatment with KOH could be used for agronomic purposes, due to its high potassium content. The employment of this non-bitter extract during the darkening step of black ripe olive processing then resulted in darker fruits with higher potassium content. Likewise, the addition of the extract into the packing brine reduced the acrylamide formation by up to 32%, although this effect was batch-dependent. KOH olive extract could be useful for the reduction in acrylamide in black ripe olives along with the enrichment of this product in phenolic compounds and potassium.

Landfill mining: A step forward to reducing CH4 emissions and enhancing CO2 sequestration from landfill

Landfill management is a major challenge for sustainable development in terms of climate change and resource scarcity. Landfill leachate contains high concentrations of nitrogen (N) and phosphorus (P), which cause eutrophication if discharged improperly. However, the nutrients can be recovered and reused as fertilizers for agriculture, contributing to resource recovery, circular economy, food security, and net zero emissions. Recent advances in landfill management have transformed landfills into resource recovery facilities that can produce nutrient-energy-material (NEM) products for applications through biological or physico-chemical process. Through a literature survey, this article reviews NEM recovery from landfills such as biogas production and composting. This work also discusses the benefits and challenges of NEM recovery for sustainability transition towards net zero emissions, while analyzes knowledge gaps and future research directions for landfill management and NEM recovery. It was conclusive from 193 articles published between 1993 and 2024 that landfill mining presents a promising solution for mitigating CH4 emissions and enhancing CO2 sequestration, both critical in reducing the overall greenhouse gas footprint of waste management. From landfill leachate and/or landfill gas, engineers can recover and recycle nutrients (for fertilizer), materials (for chemistry), and biogas (for electricity). Through landfill management, roadmaps towards decarbonization can be cost-effective and sustainable so that a maximum value of the waste can be extracted before it is discarded. Key findings reveal that CH4 emissions can be reduced by uncovering buried waste, while soil and residual organic material enhance CO2 sequestration through microbial activity. Additionally, this review highlights the economic and environmental benefits of material recovery from landfills, including metals and plastics. Overall, this work emphasizes landfill mining as a sustainable strategy for improving waste management practices, while contributing to climate change mitigation.

Drill Hole Spacing Analysis for Evaluation of Quartz Sand Resources as Residual Material from On-Land Alluvial Tin Processing based on Global Estimation Variance and Kriging Variance, with Case Study in the Bangka and Belitung Islands, Indonesia

On-land alluvial tin mining activities produce residual materials from mineral processing or mineral washing; the major one of these is quartz sand, which can be utilized in the manufacturing industry. As time goes by, the reserves of alluvial tin are decreasing, which is in line with the increasing residual material from abundant mineral processing. Mining procedures are carried out following the Indonesian government regulations, covering mining as well as reprocessing. This motivated us to evaluate the potential of quartz sand at two mining sites in Bangka and Belitung Islands. This study evaluated alluvial tin processing residual quartz sand through drill hole spacing analysis (DHSA) by comparing two geostatistics parameters, namely global estimation variance (GEV) and kriging variance (KV). Drill hole samples were taken with varying spacing, ranging from 50 to 200 m, after which geostatistical analysis was carried out. With several simulations, the incorporation of GEV and KV was able to produce the optimal drill hole spacing with measured resource categories in the range of 40 to 55 m, indicated resources in the range of 55 to 85 m, and inferred resources >85 m. Accordingly, the total estimated quartz sand resources of both sites were obtained.