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Dry anaerobic digestion (dry-AD) is an attractive process for solid wastes such as agri-food waste. However, some limitations mainly associated to lack of effective mixing, can hinder the methane production capacity of the systems. Bulking agent (BA) has been proposed as a solution to the compaction issues in systems without mechanical agitation, such as leaching bed reactors. However, effects of BA are still not clear, and, thus, the factors to consider for its dose has not been optimized yet. This work studies the effect of BA in dry-AD. Two substrates with different characteristics were proposed as models, bean peel as a lignocellulosic substrate and a mixture of food waste as a readily biodegradable substrate. Inert plastic rings were used as BA at different BA:S ratios. Assessed BA:S ratio did not affect the performance of methane production for the lignocellulosic waste, but it did significantly affect to the easily biodegradable substrate, showing up to a 28% of methane production increase. This result could be due to the presence of lignocellulosic compounds in the bean peel, behaving like a natural BA. In assays with an increased bed height, the compaction of the system was more severe, resulting in the rapid acidification of the processes. At these conditions, the positive effect of BA addition was more marked, allowing methane production and no acidification of the system. Thus, the addition of BA is a suitable strategy for improving methane production or stability in dry-AD systems without requiring the stirring of the systems. • Bulking agent (BA) addition is assessed as alternative to stirring in dry AD. • Positive effects by BA was due to an increase of the porosity in the digester bed. • Optimal BA:S ratio was strongly dependent on the characteristics of the substrate. • Low lignocellulosic content substrates were more favoured by BA addition. • BA addition was able to avoid acidification by enhancing the methanogenic activity. [ABSTRACT FROM AUTHOR]

Nanomaterials are emerging as important contributors in various applications and can be used especially in environmental catalysis. Herein, a brief summary on the basic knowledge of supercritical hydrothermal synthesis (SCWHS) is presented, including the synthesized functional nanomaterials, the effects of different experimental conditions on the properties of nanoparticles, and examples of their applications in environmental catalysis, highlighting the environmental and economic advantages of SCWHS. This review focuses on supercritical water as an environmentally friendly particle engineering tool for the production of high-quality, high-yield nanoparticles and the possibility of achieving their continuous production in industry. Nanoparticles are nucleated within a short time and their particle size can be controlled by SCWHS. Therefore, attention is given to the relationship between the formation and experimental conditions, as well as the properties of the obtained material in terms of particle size, surface area, crystallinity, morphology and surface properties. In addition, SCWHS can combine organic wastewater treatment, waste resource utilization and nanoparticle synthesis, and the in situ-generated nanoparticles can promote the oxidation of organic wastewater and the resourceful conversion of solid wastes as well as have production value as a by-product. The work may provide guidance for the further development of SCWHS, preparation of functional nanomaterials, and exploration of multiple applications. [ABSTRACT FROM AUTHOR]

Membranes with precise Li+/Na+ and Li+/K+ separations are imperative for lithium extraction from brine to address the lithium supply shortage. However, achieving this goal remains a daunting challenge due to the similar valence, chemical properties, and subtle atomic‐scale distinctions among these monovalent cations. Herein, inspired by the strict size‐sieving effect of biological ion channels, a membrane is presented based on nonporous crystalline materials featuring structurally rigid, dimensionally confined, and long‐range ordered ion channels that exclusively permeate naked Li+ but block Na+ and K+. This naked‐Li+‐sieving behavior not only enables unprecedented Li+/Na+ and Li+/K+ selectivities up to 2707.4 and 5109.8, respectively, even surpassing the state‐of‐the‐art membranes by at least two orders of magnitude, but also demonstrates impressive Li+/Mg2+ and Li+/Ca2+ separation capabilities. Moreover, this bioinspired membrane has to be utilized for creating a one‐step lithium extraction strategy from natural brines rich in Na+, K+, and Mg2+ without utilizing chemicals or creating solid waste, and it simultaneously produces hydrogen. This research has proposed a new type of ion‐sieving membrane and also provides an envisioning of the design paradigm and development of advanced membranes, ion separation, and lithium extraction. [ABSTRACT FROM AUTHOR]

Boron-doped biochar (B-BC) was synthesized by pyrolysis using solid waste of sorghum straw as raw material. The specific surface area of B-BC increased significantly by 2.38 times compared to that of pure BC. This enhancement allowed B-BC (0.3 g L−1) to achieve complete adsorption of 10 mg L−1 tartrazine (TTZ) within 40 min. Moreover, acidic conditions were more favorable for TTZ adsorption, achieving complete removal of TTZ in only 15 min at a pH of 3.0. Interestingly, the adsorption rate of TTZ by B-BC in the presence of 0.05 M Cl− was approximately 2.12 times higher than that in the absence of Cl−. When other background electrolytes were present, excluding PO43−, complete adsorption of TTZ could also be achieved within 60 min. Thermodynamic analysis and DFT calculations described the parameters of B-BC for TTZ adsorption, including Δ G Θ (< 0 kJ mol−1), Δ H Θ (− 2.199 kJ mol−1), Δ S Θ (− 6.068 J mol−1 K−1), and the adsorption energy (Eads = − 0.6919 eV), indicating a tendency towards a spontaneous adsorption process. Moreover, the strong electron transfer ability of B-BC and the oxygen-containing groups promoted the activation of PDS and generation of active substances such as 1O2, O2•−, and SO4•−, thereby degrading TTZ into products with lower biological toxicity. When the added PDS was only 0.1 mM, the degradation rate constant of TTZ could reach 0.1481 min−1. Furthermore, boron doping enhanced the stability of biochar, enabling the complete removal of 10 mg L−1 TTZ even after recycling and regeneration. In summary, this study offers a practical solution for the resource utilization of solid waste sorghum straw and the treatment of TTZ-polluted wastewater. Highlights: Boron doping significantly increased the specific surface area of biochar by 2.38 times. B-BC exhibited complete adsorption of TTZ in only 15 min at a pH of 3.0. Addition of 0.05 M Cl− increased the adsorption rate of TTZ on B-BC by 1.12 times. Free radicals and nonradicals contributed to TTZ degradation in B-BC/PDS system. Degradation products of TTZ displayed reduced toxicity to typical aquatic organisms. [ABSTRACT FROM AUTHOR]

In the process of the development of the ceramic industry, a large amount of ceramic solid waste is generated, and how to make high‐value reuse of ceramic solid waste has also become a problem of common concern. In this article, a new method of making porous thermal insulation materials reusing waste electric porcelain was successfully developed. In this work, a porous light refractory with bulk density of 0.99 g/cm3 and apparent porosity of 59% was prepared by the novel method. Which room temperature flexural and compressive strengths are 11.52 MPa and 1.84 MPa, respectively. These properties makes the waste electric porcelain‐based porous light refractory can be applicated as lightweight heat insulation materials for high‐temperature kilns, high‐temperature catalyst carriers, high‐temperature phase‐change heat storage support materials, etc. which will create higher application value and research significance. [ABSTRACT FROM AUTHOR]

Hydrogen plays a fundamental role in the context of decarbonization as a pillar of energy transition. It can be produced through different manners, including from residual biomass. Aiming to mitigate the effects of climate change, this study seeks to estimate Greenhouse Gas (GHG) emissions, specifically the carbon footprint of biohydrogen (Bio-H 2) derived from dark fermentation of Organic Fractions of Urban Solid Waste (OFUSW) and reforming biomethane from Landfill Gas (LFG) at landfill consortia. The goal of this study is to address the question of how Low Carbon Emission Hydrogen generation may be achieved. Population and solid waste generation projections for the next 20 years at landfill consortia in the Brazilian southeast were estimated. The potential for generating (Bio-H 2) and Life Cycle Analysis (LCA) were defined according to ABNT ISO 14040 and ABNT ISO 14044 using the two aforementioned scenarios. The results showed that the bio-H 2 potential generation from methane flows were 654, 517, 453, and 162 million m³, respectively for the states of São Paulo, Minas Gerais, Rio de Janeiro, and Espírito Santo. Moreover, the carbon footprint calculations for bio-H 2 generation showed that up to 9.23 and 18.41 gCO 2eq /MJ, respectively, are generated by producing 1.0 MJ of hydrogen via dark fermentation and the biogas reforming process. These values indicated a reduction of up to 75% for biogas reformation, and 87% for dark fermentation, compared to conventional hydrogen production from natural gas. This underscores the significance of waste energy recovery management aiming to achieve the goal of producing Low Carbon Emission Hydrogen. • Economic feasibility of leveraging H 2 from biogas for sanitary landfill in Brazil. • Two processes were analyzed: steam methane reforming and pyrolysis reforming. • Biogas production was estimated along with the production of hydrogen and ammonia. • Ammonia attainment from H 2 and the Levelized Cost of Ammonia were determined. • Installed capacity of consortia varied from 12,738.08 to 1,716,651.77 kgH 2 /year. [ABSTRACT FROM AUTHOR]

As one of the main waste streams of the manufacturing process of solid oxide cells (SOCs), scrap half-cells - discarded before the deposition of the barrier layer and the air electrode - imply the loss of significant quantities of ceramic composite material containing critical and hazardous elements, namely yttria-stabilized zirconia (YSZ) and NiO. These materials represent more than 90 wt% of an entire anode-supported cell. In this contribution, scrap half-cells were fragmented and subjected to three subsequent milling and sieving (below 25 μm) steps to recover composite NiO-YSZ powders with the appropriate specifications for reuse in SOC manufacturing. The overall characterization in terms of specific surface area, particle size distribution and crystalline phase retention confirmed the suitability of the recovered powders. Half-cells were manufactured including 30 wt% of recovered NiO-YSZ composite powders in their fuel electrode support, produced via tape-casting in combination with 70 wt% of virgin materials. The obtained cells were morphologically, mechanically and electrochemically tested and compared against standard cells constituted by 100 wt% of virgin materials. The electrochemical characterization highlighted 0.68 A cm−2 for the standard and recycled cells, at 600 °C and 0.7 V, while at 650 °C and same voltage both cells measured 1.12 A cm−2. This demonstrates the feasibility of recovering scrap SOCs through the presented method. [ABSTRACT FROM AUTHOR]

In order to realize the resource utilization of solid waste and the treatment of phenol wastewater in China, a new porous ceramic granules (PCG) with the function of degrading phenol wastewater was prepared by using titanium-containing blast furnace slag, iron tailings and fly ash as raw materials, which realized the sustainable development of "treating waste with waste". The effects of different pore forming agents on the structure, morphology, ionic state of PCG samples and the adsorption behavior of phenol in aqueous solution were investigated. The results show that the change of pore forming agent has no obvious change on the crystal structure. When carbon powder (CP) and starch (SH) are used as pore forming agents, the internal pore structure is relatively dense and less porous, and it is not easy to form liquid channels. When ammonia bicarbonate (NH) is used as pore-forming agents, the internal pore structure is very developed and has many three-dimensional pore structures. Under the conditions of PH 2, phenol concentration 10 mg/L and solid-liquid ratio 3 g/L, TOC removal rates of CP-PCG, SH-PCG and NH-PCG samples after 72 h adsorption reaction were 39.10 %, 14.00 % and 93.29 %, respectively. In addition, the surface functional groups, hydrogen bonds and π-π interactions of PCG samples may be involved in the adsorption of phenol. This work not only provides a low-cost, environmentally friendly and simple technology for phenol-containing wastewater treatment, but also provides a new idea for the effective use of solid waste resources. [ABSTRACT FROM AUTHOR]

Expanding waste-to-energy (WtE) facilities is difficult, and with tightening incineration regulations, improvements in WtE facility operations are required to dispose of waste that is increasing by an average of 4.8% annually. To achieve this, an intelligent combustion control (ICC) system was studied using digital technologies such as the Internet of Things and artificial intelligence to improve the operation of WtE facilities. The ICC system in this study is composed of three modules: perception, decision, and control. Perception: collecting and visualizing digital data on the operating status of WtE facilities; Decision: using AI to propose optimal operation methods; Control: automatically controlling the WtE facility according to the AI-suggested optimization methods. The ICC system was applied to the "G" WtE facility, a solid waste WtE facility operating in Gyeonggi province, Republic of Korea, and the digital data collected over six months showed high quality, with low delay and a data loss rate of only 0.12%. Additionally, in January 2024, the ICC system was used to automatically control the second forced draft fan and induced draft fan over a four-day period. As a result, the incinerator flue gas temperature decreased by 0.66%, steam flow rate improved by 2.41%, power generation increased by 3.09%, CO emissions were reduced by 60.72%, and NOx emissions decreased by 7.33%. Future research will expand the ICC system to include the automatic control of the first forced draft fan and the operation time of the stoker. [ABSTRACT FROM AUTHOR]

This study explores the utilization of municipal solid waste incineration fly ash (MSWIFA) in geopolymer concrete, focusing on compressive strength and heavy metal leachability. MSWIFA was sourced from a Shenzhen waste incineration plant and pretreated by washing to remove soluble salts. Geopolymer concrete was prepared incorporate with washed or unwashed MSWIFA and tested under different pH conditions (2.88, 4.20, and 10.0). Optimal compressive strength was achieved with a Si/Al ratio of 1.5, water/Na ratio of 10, and sand-binder ratio of 0.6. The washing pretreatment significantly enhanced compressive strength, particularly under alkaline conditions, with GP-WFA (washed MSWIFA) exhibiting a 49.6% increase in compressive strength, compared to a 21.3% increase in GP-FA (unwashed MSWIFA). Additionally, GP-WFA's compressive strength reached 41.7 MPa, comparable to that of the control (GP-control) at 43.7 MPa. Leaching tests showed that acidic conditions (pH 2.88) promoted heavy metal leaching, which increased over the leaching time, while an alkaline environment significantly reduced the leachability of heavy metals. These findings highlight the potential of using washed MSWIFA in geopolymer concrete, promoting sustainable construction practices, particularly in alkaline conditions. [ABSTRACT FROM AUTHOR]

Understanding the strength development of alkali-activated materials (AAMs) with fly ash (FA) and granulated blast furnace slag (GBFS) is crucial for designing high-performance AAMs. This study investigates the strength development mechanism of AAMs using machine learning. A total of 616 uniaxial compressive strength (UCS) data points from FA-GBFS-based AAM mixtures were collected from published literature to train four tree-based machine learning models. Among these models, Gradient Boosting Regression (GBR) demonstrated the highest prediction accuracy, with a correlation coefficient (R-value) of 0.970 and a root mean square error (RMSE) of 4.110 MPa on the test dataset. The SHapley Additive exPlanations (SHAP) analysis revealed that water content is the most influential variable in strength development, followed by curing periods. The study recommends a calcium-to-silicon ratio of around 1.3, a sodium-to-aluminum ratio slightly below 1, and a silicon-to-aluminum ratio slightly above 3 for optimal AAM performance. The proposed design model was validated through laboratory experiments with FA-GBFS-based AAM mixtures, confirming the model's reliability. This research provides novel insights into the strength development mechanism of AAMs and offers a practical guide for elemental design, potentially leading to more sustainable construction materials. [ABSTRACT FROM AUTHOR]

Biomass bottom ash (BBA) is a by-product of the energy industry and is produced from biomass-fired thermal power plants. They represent the coarsest fraction of the recovered ash and are mostly landfilled. Several researchers have investigated the feasibility of the use of BBA as a replacement for natural aggregates in cementitious material. The utilisation of BBA in the manufacturing of concrete provides an economic and ecological way to upcycle it. At the same time, its use conserves natural resources and promotes sustainability. This review article first presents the chemical, mineralogical and physical properties of BBA, to highlight the possible effects on cementitious materials and the interest in valorising them as a building material. Secondly, the focus is on the utilisation of BBA incorporated in place of natural aggregates used in the manufacturing of concrete. This review investigates the multi-physical properties of concrete manufactured with the partial incorporation of BBA. This substitution leads to decreased workability, which can be limited by the use of admixtures. In the hardened state, a reduction in the mechanical properties is shown with BBA replacement. However, many experimental works show that BBA can be used in appropriate proportions to maintain the specified properties of the concrete. [ABSTRACT FROM AUTHOR]

• Critical application of the Waste Flow Diagram methodology in Tuy Hoa city, Vietnam. • Plastic leakage into the aquatic environment from 0.8 to 2.7 kg/cap/year. • The SWM collection system is the main contributor to plastic leakages. Plastic mismanagement and its subsequent pollution by rapid economic development and urbanisation pose significant challenges for modern world society. Notwithstanding one of the main sources for macro plastic leakage into the ocean from land, precise assessment of plastic pollution origins from Southeast Asia is yet to be clearly examined. In order to make informed decisions and prioritise areas of improvement it is required to better understand the waste leakage dynamics at the local level. In this work, the Waste Flow Diagram (WFD) was applied to understand the sources and fates of plastics leaking from the solid waste management system for the case of Tuy Hoa City, Phu Yen, Vietnam. The study shows scenarios of leakage into the aquatic environment ranging from 0.8 to 2.7 kg/cap/year, which originates mainly from the collection system. Targeted improvements to this stage of the service could reduce leakages and the overall environmental impacts of mismanaged plastic waste. The results of this study show the necessity and importance of having up to date and reliable data to better inform stakeholders and service planning, facilitating efficient action against plastic pollution. As the first peer-reviewed scientific article critically applying the WFD, this work highlights the steps and challenges of the methodology and critically analyses different methodological pathways. [ABSTRACT FROM AUTHOR]

• Monitored microbial shifts during anaerobic degradation of two types of food waste. • Sampling of both leachate and solids revealed microbial composition differences. • Substrates led to different population dynamics and methanogenic pathways. A key question in anaerobic microbial ecology is how microbial communities develop over different stages of waste decomposition and whether these changes are specific to waste types. We destructively sampled over time 26 replicate bioreactors cultivated on fruit/vegetable waste (FVW) and meat waste (MW) based on pre-defined waste components and composition. To characterize community shifts, we examined 16S rRNA genes from both the leachate and solid fractions of the waste. Waste decomposition occurred faster in FVW than MW, as accumulation of ammonia in MW reactors led to inhibition of methanogenesis. We identified population succession during different stages of waste decomposition and linked specific populations to different waste types. Community analyses revealed underrepresentation of methanogens in the leachate fractions, emphasizing the importance of consistent and representative sampling when characterizing microbial communities in solid waste. [ABSTRACT FROM AUTHOR]

• Estimates of modeled CH 4 emission (E) data for 1,325 U.S. landfills were reviewed. • Operators use two methods to estimate E from landfills with a gas collection system. • First-order decay (FOD) method shows increasing emissions. • Collection efficiency assumption method shows decreasing emissions. • FOD method shows some agreement to remotely sensed national estimates. As part of its commitment to the United Nations Framework Convention on Climate Change, the U.S. annually develops a national estimate of methane emissions from municipal solid waste (MSW) landfills by aggregating activity data from each facility. Since 2010, the U.S. has reported a 20 % decrease in MSW landfill emissions despite a 21 % increase in tons disposed. Operator-submitted data were investigated to understand the causes of this decline. In the U.S., operators of landfills with a gas collection and control system (GCCS) calculate their facility's emissions via two separate approaches – (1) first-order decay (FOD) and (2) collection efficiency assumption (CEA) − and select either result to feed into the annual inventory. The FOD model predicts methane generation proportional to waste disposal and that approach calculated a 19 % increase in total methane generated from 2010 to 2022, whereas generation via the CEA approach decreased by 8.9 %. The amount of measured methane collected has increased 7.5 % for the same years. Discrepancies between the two models' generated methane, assumed gas collection efficiencies, and oxidized methane compound into substantive differences in national estimates. Operators more frequently select the CEA method, which results in decreased national estimates. If only the FOD method was used, U.S. MSW landfill emissions would be 1.3-1.7 times greater than current estimates which is similar to recent extrapolations from remote sensing campaigns in the U.S. Both models contain parameters with large inherent uncertainty. Without measurement methods that continuously quantify both point-source and diffuse emissions, an assessment of either equation's accuracy cannot be made. [ABSTRACT FROM AUTHOR]

Aluminum electrolysis spent cathode carbon (SCC), as typical solid hazardous waste, poses significant environmental risks. Harmless treatment of SCC and recycling of its carbon component are important research areas. In this study, SCC was subjected to microwave hydrothermal acid leaching to remove harmful components, followed by the production of high-quality graphite via iron-catalyzed graphitization. The effects of reaction temperature, heating time, and catalyst loading on the graphitization conversion of SCC were investigated. The catalytic graphitization process of SCC was optimized using the response surface method. The results show that when the reaction temperature is 1520 °C, the heating time is 85.24 min, and the catalyst loading is 46.15 wt%, the graphitization degree of the sample is 97.61 %. The samples prepared under the optimal conditions were characterized using XRD, Raman, SEM, and TEM. The results reveal that the catalytic graphitization process significantly influences the conversion of microcrystalline structures in SCC into graphite structures. The iron-catalyzed transformation of microcrystalline carbon was analyzed to elucidate the graphitization transformation mechanism. This study offers an effective pathway for the high-value utilization of SCC. It also serves as a technical reference for the catalytic graphitization conversion of carbon materials. [ABSTRACT FROM AUTHOR]

Three groups of composite cementitious materials (CCMs) were prepared by separate grinding, mixed grinding, and cascade grinding using iron and steel solid waste (ISSW) materials (granulated blast furnace slag (GBFS), iron ore tailings (IOTs), steel slag (SS) and desulfurization gypsum (DG)), and the influence on the strength of CCMs was investigated under different water-binder ratios (w/b). Then, the hydration hardening mechanism of the CCMs was revealed via hydration heat analysis, phase composition and structural analysis of hydration products. The results show that the properties of the CCMs prepared by cascade grinding (CGC) is better than that prepared by separate grinding and mixed grinding. When the mass percentage of IOTs and SS in the CGC was 2:3, the mix proportion of CGC is SS+IOTs: GBFS: DG=36:51.5:12.5, mixed with 1.0 % Na 2 SO 4 and 1.2 % Na 2 SiO 3 ˑ9 H 2 O of the CGC, the compressive strength (CS) of mortar sample containing CGC in 28-days and 180-days reach 52.3 MPa and 70.7 MPa respectively under the conditions of standard curing and low water-binder ratios. The hydration degree of pure cement is higher than that of CGC, but types of the hydration products were similar with cement, mainly were Ca(OH) 2 , iolite, ettringite (AFt) and C-S-H gel. The CGC can greatly reduce the hydration heat of CCMs system in early age, and is suitable for massive concrete structures in which elevated temperature can be kept for a long time. [ABSTRACT FROM AUTHOR]

Geopolymers derived from solid waste can effectively remediate heavy metal polluted sites, achieving the ideal fusion of solid waste utilization and environmental remediation. Red mud and blast furnace slag were used to develop a geopolymer for the remediation of composite heavy metal-contaminated soils, focusing on Cd(II)-, Pb(II)-, Cu(II)-, and Zn(II)-contaminated soils. Uniaxial compressive strength tests, toxicity characteristic leaching procedures, pH change characteristics, and pH gradient tests were performed on the solidified/stabilized soil. The results showed that increasing the red mud-blast furnace slag content and curing age significantly enhanced the unconfined compressive strength. Furthermore, it suppressed the leaching of heavy metals in the solidified/stabilized soil. Notably, the treatment effectiveness of Cu(II) and Zn(II) was superior to that of Cd(II) and Pb(II). The leaching concentrations of Cd(II), Pb(II), and Zn(II) decreased in acidic to weakly alkaline environments but increased in strongly alkaline environments. However, the impact of curing age and initial heavy metal content on the pH of the solidified/stabilized soil was the opposite. In conclusion, red mud and blast furnace slag exhibited superior solidification/stabilization effects compared to cement. As environmental protection awareness grows and technology continues to evolve, geopolymers derived from red mud and blast furnace slag will play a greater role in pollution control and remediation, showcasing broad application prospects. [ABSTRACT FROM AUTHOR]

An innovative decision matrix has been developed to guide the selection and implementation of Pneumatic Urban Solid Waste Collection Systems (PUSWCS) in smart city projects. This study comprehensively collects and analyzes data on the advantages and disadvantages of pneumatic collection systems from technical, economic, and social perspectives. A decision-making tool was created to address the complexities of evaluating the desirability of incorporating PUSWCS in municipalities or specific areas, using a holistic approach. The tool assesses the technical, economic, and social feasibility of implementing PUSWCS, aligning it with the United Nations' Sustainable Development Goals (SDGs). Specific variables are measured to assess compliance with the SDGs, distinguishing technical aspects from economic and social aspects. The methodology includes surveys of system users and technicians, expert assessments, and the development of a decision matrix that cross-references study variables and SDGs. The matrix assigns numerical values to the Magnitude (M) and Impact (I) of each variable, enabling quantitative interpretation. This holistic approach accommodates the complexities of waste management and diverse stakeholder perspectives. The results demonstrate the matrix's effectiveness in accurately assessing the desirability of implementing PUSWCS. This confirms the matrix's ability to optimally integrate with innovative smart city concepts and align with long-term sustainability goals. The study concludes that the design of the decision matrix allows the collection of information from experts, users, and stakeholders about economic, social, and environmental variables and relates them to the SDGs, to obtain a numerical result that allows to decide whether in a given urban environment it is advisable to implement a PUSWCS. [ABSTRACT FROM AUTHOR]

Emerging contaminants (ECs) present a significant risk to both the ecological environment and human health. Landfill leachate (LL) often contains elevated EC levels, posing a potential risk to localized groundwater. This study aimed to characterize ECs in municipal solid waste landfills (MSWLs) and hazardous waste landfills (HWLs) in northeast (NE) China. One and three HWLs and MSWLs in NE China with varying types, operational years, and impermeable layers were selected as case studies, respectively. Statistical analysis of 62 indicators of nine ECs in leachate and the groundwater environment indicated the presence of perfluorinated compounds (PFCs), antibiotics, alkylphenols (APs), and bisphenol A (BPA). The leachates of the four landfills exhibited elevated concentrations of ECs of 21.03 μg/L, 40.04 μg/L, 14.54 μg/L, and 43.05 μg/L for PFCs, antibiotics, Aps, and BPA, respectively. There was a positive correlation between the highest concentrations of ECs in groundwater and those in leachate as well as with operational duration of the landfill; in contrast, groundwater EC was negatively correlated with the degree of impermeability. This study can guide future management of ECs in landfills and hazardous waste sites in China, particularly in NE China. [ABSTRACT FROM AUTHOR]

This research investigates the use of municipal solid waste cremated fly ash as a viable substitute for natural sand in building methodologies, with a focus on sustainability. The waste material is used in the manufacturing of concrete roof tiles that are combined with solar PV systems, providing advantages in terms of both thermal comfort and improved energy efficiency. These tiles exhibit thermal insulation prowess by effectively preserving a 2-degree temperature differential and collecting heat from solar panels to enhance their energy-production efficiency. In order to enhance performance even further, aluminium foil is strategically placed on all four sides of the roof walls. The foil acts as a reflector, redirecting solar energy towards the tiles, which leads to a 5% boost in power generation. Particular alignments, such as positioning in an east-west or north-south direction, result in further enhancements in performance of 4% and 3%, respectively. This comprehensive approach not only confirms the use of waste materials for environmentally friendly construction but also emphasizes their crucial role in promoting energy-efficient building methods. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is an efficient technology for treating organic solid wastes, and the volatile fatty acids (VFAs) produced during AD have significant value due to their wide range of applications and higher added value compared to methane. This study investigated the long-term effects of high solid content and straw proportion in mixed substrates (straw, sludge, and food wastes) on VFAs production through semi-continuous reactors under thermophilic and mesophilic conditions. Results showed that both reactors achieved a maximum VFAs concentration of ~ 22 g/L as the straw proportion increased to 50%. Acetate (48.3 – 64.5%) was the main component of produced VFAs in both reactors, while butyrate and propionate production in thermophilic temperature were superior compared to mesophilic conditions. Microbial community analysis revealed that Defluviitoga plays a pivotal role in acidogenesis within both reactors; besides, unclassified Hungateiclostridiaceae and Caproiciproducen were found to be dominant in thermophilic reactor, while Lachnospiraceae_NK3A20_group and Rikenellaceae_RC9_gut_group were essential for VFAs production under mesophilic conditions. These findings provide valuable insights for the biotechnological exploration of acidogenic fermentation for large-scale mechanized production of VFAs from agricultural wastes. [ABSTRACT FROM AUTHOR]

Coal gasification coarse slag (CGCS) has become a bulk coal-based solid waste that threatens the ecological environment. The high moisture content of carbon-rich coal coarse gasification slag (CR-CGCS) seriously limits its utilization. In this study, a pore water releasing method was proposed to promote the dewatering of CR-CGCS through size reduction with surface modification. Hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and kerosene were added during the grinding process, respectively. The results showed that kerosene can significantly improve the dewatering efficiency of CR-CGCS more than CTAB and SDS. The final moisture content of the CR-CGCS could be reduced from 47.50% to 33.01%. The SEM and FTIR results illustrated that kerosene could effectively reduce the content of oxygen-containing functional groups on the surface of CR-CGCS more than CTAB and SDS. Meanwhile, the PVM results showed that CR-CGCS modified by kerosene tended to form hydrophobic agglomerates. The LF-NMR results indicated that only the water in the macropores of CR-CGCS could be released in grinding process, but the water in micropores could be reduced when kerosene, CTAB, or SDS was added in grinding. This study provides new insight into enhancing the dewatering of CR-CGCS and theoretical support for the efficient utilization of CR-CGCS. [ABSTRACT FROM AUTHOR]

The article discusses the current problem of energy utilization of municipal solid waste, most of which is currently buried in landfills. An assessment of greenhouse gas emissions from these anthropogenic objects is provided. It is noted that a promising direction for utilization of landfill biogas is the production of biohydrogen. The authors present the results of laboratory studies on the production of biomethane from organic waste with its further conversion into biohydrogen. Using the example of a large landfill for municipal solid waste, a possible geo-ecological effect is shown by reducing greenhouse gas emissions during the energy utilization of biogas. [ABSTRACT FROM AUTHOR]

The stone waste generated by stone industry occupy land resources, cause safety hazards and need to be efficiently resourcefully utilized. In this study, the CGF solid waste based binder (abbreviated as CGF) with calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), and fly ash (FA) as components was developed to solidify the stone waste. Through "treating waste with waste", the resource utilization of solid waste was realized. The mechanical properties and reaction mechanism of CGF solidified stone waste were investigated through unconfined compressive strength (UCS), XRD, and SEM–EDS tests. The results show that CGF has the better solidify effect on stone waste, and its strength meets the requirements of the road base material standards. Compared to cement, the CGF solidified stone waste existed higher UCS at both 7 and 28 d of curing. The UCS of CGF solidified stone waste reaches 2.93 and 4.42 MPa under curing of 7 and 28 d at 5% binder content, which is 1.61 and 1.37 times higher that of P.O. 42.5 cement. Furthermore, the primary mineral-based stone wastes will not react with the binder, and the CGF generates gelling products such as C-S–H C-A-H, and C-A-S–H through alkali-activated reactions between the components of CGF. These gelling products enhance the UCS of solidified stone wastes through cementing and filling effects. The findings provide a feasible approach with low-carbon emission and low-cost for resourceful utilization of stone wastes. [ABSTRACT FROM AUTHOR]

There are about 3159 open dump sites in India, which cause severe environmental pollution and are a danger to public health. This study demonstrates that the embedded resources in these dumpsites can be recovered profitably. The paper surveys the excavation, segregation, re-cycling and re-use of an open dumpsite containing legacy waste, at a cost of 8 $/m3 of rubbish, recovered, incinerable and inert fractions. A land reclamation of 3.16 ha yielding 1048 tonnes of refuse-derived fuel was achieved. This study demonstrates that dumpsite mining can be profitable while preventing the environmental hazards caused by existing waste dump sites in most Indian cities. [ABSTRACT FROM AUTHOR]

This study aimed to increase the scale of oil‐based drilling cuttings (OBDCs) resource utilization in the ceramic industry. The sintering process and mechanism were explored based on the analysis of physicochemical properties, phase transitions, and microstructure. The results showed that (1) The main ceramic‐technological characteristics of the OBDC were determined, which belonged to high‐silica solid waste with a high Si–Al ratio and a low acid–base ratio of oxides. (2) The low meltability temperature of the OBDC could largely influence the determination of the sintering temperature range for ceramic products. (3) The chemical components OBDC provided were involved in the formation of molten phases, which could affect dimensional accuracy and mechanical properties. Meanwhile, the dolomite promoted the formation of closed pores and enhanced lightweight performance. (4) Before 800°C, dolomite decomposed and reacted with SiO2 to form silicate, and then a new feldspar crystal appeared. After 1000°C, orthoclase completely melted into the molten phase, only two phases of quartz and diopside existed in the material until 1150°C. When the temperature was higher than 1350°C, the glass transition of the phase was basically intensified. (5) In the analyzed scenarios, the results indicated OBDC can only be doped in low contents and degrades the ceramic material properties. [ABSTRACT FROM AUTHOR]

As organic waste is converted to usable amendments via composting, there are large CO2 emissions associated with the decomposition of organic matter via microorganisms. While the active composting phase produces the largest emissions over a short duration, compost can often be stored during and after the maturation phase for much longer periods of time, increasing cumulative emissions. As such, the objectives of this study were to examine the spatial and temporal variability associated with in situ emissions sampling while identifying the environmental and chemical controls on emissions in windrow composting facilities during and after the maturation phase. A total of 665 flux measurements were taken from four windrows representing different ages and compositions between June and November 2020. Factorial analysis of covariance (ANOVA) was used to determine the variability between sampling locations, while multiple linear regression was used to identify those parameters which had the most influence on CO2 flux. Emissions showed significant variability over time that were attributed to ambient temperatures. During the summer, each windrow reached peak emissions between 5.0 and 32.3 g CO2 m-2 hr-1. As temperatures cooled, the windrows saw a 62%-86% decline in emissions, generally falling below 2 g CO2 m-2 hr-1. Significant differences occurred between the top-most sampling location and all others on the windrow, emitting between 33%-100% more CO2. The environmental controls of surface temperature, moisture content, and internal temperature showed the highest influence on emissions (R2 = 0.62). Chemical properties including organic nitrogen, carbon, pH, magnesium, and nitrate also showed significant influence (R2 = 0.43). This research has shown that environmental factors including temperature and moisture show the strongest influence over emission rates in mature compost. A significant negative effect of organic nitrogen on CO2 flux was found, indicating that increased presence of organic nitrogen would aid in the retention of carbon after the maturation phase, acting to lower total emissions. [ABSTRACT FROM AUTHOR]

Steel slag (SS) as solid waste, has low resource utilization efficiency and seriously endangers environmental safety and human health. To explore the potential utilization value of SS and address the flammability challenge of rigid polyurethane foam (RPUF), with a novel flame‐retardant system composed by SS and dimethyl methyl phosphonate (DMMP) was explored. The DMMP/SS system effectively improved the high temperature stability of the RPUF composites. When the mass ratio of SS and DMMP was 1:1, the limiting oxygen index of RPUF/DMMP/SS reached 23.1 vol% and UL‐94 vertical combustion tests passed V‐2 level. Upon incorporation of 15 wt% DMMP, the initial decomposition temperature (T−5 wt%) reduced to 165.3°C, a decrease of 32.2%, while the Tmax2 and residue yield at 700°C exhibited negligible alteration. The peak heat release rate of RPUF/DMMP/SS composite (118.20 W g−1) was 11.02% lower than that of pure RPUF, indicating the significant enhancement of fire safety of the composites. Results confirmed that a synergistic flame‐retardant mechanism was existed between DMMP and SS in enhancing the fire safety of RPUF composite. Introducing a 20 wt% SS content reduces the ID/IG ratio to 1.85, thereby markedly enhancing its heat resistance. This work provides a new application field of SS and paves a novel approach to enhance fire safety of polymers. [ABSTRACT FROM AUTHOR]

A substantial amount of process waste is generated during the manufacture of soft‐wheat products (SWPs), such as biscuits/cookies, crackers, wafers, and cakes. A small portion of waste is reused in specific biscuits, whereas the rest is usually discarded. This study aimed to investigate the suitability of this waste for the co‐production of bioethanol and fatty acid methyl esters (FAMEs or biodiesel). Two groups of waste generated in the SWP industry were included in the study: (a) the waste of low‐moisture (<10%) biscuits, crackers, and wafer sheets with no fillings and/or coatings, and (b) the waste of high‐moisture (>10%) biscuits, crackers, wafers, and cakes with fillings and/or coatings. The study involved extracting each sample with hexane, and the recovered fat was converted to the FAME through alkali‐catalyzed transesterification. The remaining carbohydrate‐rich fraction was then converted to bioethanol through amylolytic hydrolysis and yeast fermentation. A great portion (92.42%–93.17%) of the fat was extracted from the wastes and converted to the FAME with adequate yields (13.81–14.55 g FAME/g waste, dm) and acceptable conversion efficiencies (85.19%–89.04%). However, bioethanol production from the defatted carbohydrate‐rich fractions proceeded rather slowly, yielding only 16.54–18.02 (g ethanol per g of waste, dm), corresponding to fermentation efficiencies ranging from 43.32% to 48.29%. Upon the co‐production of FAME and ethanol, a considerable amount (50.93%–53.08%) of waste solids remained in the residue fraction. These findings indicated that production of the FAME with adequate yields and conversion efficiencies is viable from the SWP industry wastes; however, bioethanol yields and fermentation efficiencies are rather limited, which warrants further investigation. Practical Application: The soft‐wheat processing industry generates 1%–5% of total production as waste. The waste was studied to produce FAME and bioethanol. The fat was extracted from the waste and converted to FAME. Bioethanol yields and fermentation efficiencies are limited due to dough modifiers and antimicrobial additives used in SWP production. Further research is required to improve ethanol yield. [ABSTRACT FROM AUTHOR]

Background: Several Acinetobacter species live in different ecosystems, such as soil, freshwater, wastewater, and solid wastes, which has attracted considerable research interests in public health and agriculture. Methods: We assessed the distribution of Acinetobacter baumannii and Acinetobacter nosocomialis in three freshwater resources (Great Fish, Keiskemma, and Tyhume rivers) in South Africa between April 2017–March 2018. Molecular identification of Acinetobacter species was performed using Acinetobacter-specific primers targeting the recA gene, whilst confirmed species were further delineated into A. baumannii and A. nosocomialis. Similarly, virulence genes; afa/draBC, epsA, fimH, OmpA, PAI, sfa/focDE, and traT in the two Acinetobacter species were assessed. Results: Our finding revealed that 410 (48.58%) and 23 (2.7%) of the isolates were confirmed as A. baumannii and A. nosocomalis, respectively. Additionally, three hundred and eight (75.12%) A. baumannii and three (13.04%) A. nosocomialis exhibited one or more of the virulence genes among the seven tested. OmpA was the most prevalent virulence gene in A. baumannii in freshwater sources. Conclusions: The distribution of clinically important Acinetobacter species in the freshwater sources studied suggests possible contamination such as the release of hospital wastewater and other clinical wastes into the environment thereby posing a risk to public health. [ABSTRACT FROM AUTHOR]

In this research, the energy potential of switchgrass (SG) was analyzed to find promising directions for producing bioenergy from this biomass. The first direction is determining the thermal energy of bioethanol extracted from SG biomass after its pretreatment, enzymatic hydrolysis (saccharification), and fermentation of the resulting glucose. It was established that after a two-stage pretreatment of 1 ton of SG with dilute solutions of nitric acid and alkali, the largest amount of bioethanol can be extracted with an energy potential of 4.9 GJ. It is also shown that by the utilization of solid and liquid waste, the production cost of bioethanol can be reduced. On the other hand, the direct combustion of 1 ton of the initial SG biomass used as a solid biofuel provides an increased amount of thermal energy of 18.3 GJ, which is 3.7 times higher than the energy potential of the resulting bioethanol extracted from 1 ton of this biomass. Thus, if the ultimate goal is to obtain the maximum energy amount, then another direction for obtaining bioenergy from biomass should be implemented, namely, direct combustion, preferably after pelletizing. Studies have shown that fuel characteristics of SG pellets such as the gross thermal energy and density of thermal energy are lower than those of wood pellets, but they can be improved if the SG biomass is densified into pellets together with binders made from polymer waste. [ABSTRACT FROM AUTHOR]

In recent years, the remediation of heavy metal-contaminated soils has attracted great attention worldwide. Previous research on the removal of toxic heavy metals from wastewater effluents through adsorption by typical solid wastes (e.g., fly ash and coal gangue) has mainly focused on the control of wastewater pollutants. In this study, a coal gangue (CG) by-product from Hancheng City was used as a raw material to prepare polymeric aluminum chloride-loaded coal gangue-based porous carbon (PAC-CGPC) by hydrothermal synthesis. This material was subsequently employed to assess its performance in mitigating Pb2+ in soils. In addition, the effects of the pore structure of the prepared material on the adsorption rates, adsorption mechanisms, and plant root uptakes of soil Pb2+ were investigated in this study. The raw CG and prepared PAC-CGPC materials exhibited specific surface areas of 1.8997 and 152.7892 m2/g, respectively. The results of adsorption kinetics and isotherms indicate that the adsorption of Pb2+ based on PAC-CGPC mainly follows a pseudo-second-order kinetic model, suggesting that chemisorption may be the dominant process. In addition, the adsorption isotherm results showed that the Freundlich model explained better the adsorption process of Pb2+, suggests that the adsorption sites of lead ions on APC-CGPC are not uniformly distributed and tend to be enriched in APC, and also shows the ion exchange between aluminum and lead ions. The thermodynamic model fitting results demonstrated the occurrence of spontaneous and exothermic PAC-CGPC-based adsorption of Pb2+, involving ion exchange and surface complexation. The effects of the PAC-CGPC addition on soybean plants were further explored through pot experiments. The results revealed substantial decreases in the Pb2+ contents in the soybean organs (roots, stems, and leaves) following the addition of the PAC-CGPC material at a dose of 3% compared with the control and raw CG groups. Furthermore, the addition of the PAC-CGPC material at a dose of 3% effectively reduced the bioavailable Pb2+ content in the soil by 82.11 and enhanced soybean growth by 15.3%. These findings demonstrated the inhibition effect of the PAC-CGPC material on the translocation of Pb2+ in the soybean seedlings. The modified CG adsorbent has highly pore structure and good hydrophilicity, making it prone to migration in unsaturated soils and, consequently, enhancing Pb2+ immobilization. This research provides theoretical support for the development of CG-based materials capable of immobilizing soil pollutants. [ABSTRACT FROM AUTHOR]

Industrial solid residual waste (ISRW) generated during and/or due to the making of energy, heat, and raw materials poses a major threat to a sustainable future due to its large production quantities and complex characteristics. Especially improper disposal of ISRW (e.g., coal ashes, municipal waste residue, and biomass ashes) not only threatens human health but can also cause environmental hazards such as water, soil, and air pollution, upsetting the global balance. Given the environmental impacts as well as increasingly stringent disposal regulations, lack of landfills, and economic constraints, more sustainable and naturally friendly management strategies are being adopted for ISRW. While numerous studies in the literature have considered various characteristics of ISRW, a complete appraisal of the entire practice, from making to disposal, is still lacking. This paper presents an overview of the making, features, and traditional and innovative managing tactics of ISRW within the context of a general legal framework. This paper provides a scientific review of the various production types, global production quantities, and characteristics of ISRW. Additionally, the orthodox management strategies of ISRWs are scrutinized from a sociological and ecological standpoint, and diverse techniques for more viable and secure management are elucidated. This review culminates in an examination of the global impact and advantages of ISRW management policies based on legislation and regulations. Consequently, this paper seeks to elucidate the extant practices and a few recent advancements pertaining to ISRWs. Additionally, it underscores the ecological, sociological, and economic issues engendered by ISRWs and proposes innovative applications and production technologies. [ABSTRACT FROM AUTHOR]

The continuous dumping of industrial solid wastes into the immediate environment is incommodious since these waste materials cause pollution and serious hazards to human health. In addition, these solid wastes are complex and consist of toxic chemical substances, heavy metals, and valuable metals, hence warranting treatment before disposal. Bioleaching is a green and sustainable technology for the solubilization and mobilization of metals from solid matrices. The leaching efficacy is contingent on the types and physiology of the organisms, the elemental content of the solid wastes, and the presence of appropriate bioprocess parameters at optimum conditions. Extremophilic microbes, including thermophiles, acidophiles, alkaliphiles, and halophiles, are recognized as excellent biological agents for the efficient bioextraction of metals from industrial solid wastes due to their aptitude for survival under harsh bioleaching conditions. Therefore, this review provides insights into the employability of extremophilic microorganisms as a biofactory for the recovery of valuable metals from various industrial solid wastes. More so, it discusses the sustainability of the bioleaching technique in terms of its life cycle assessment (LCA) and techno-economic analysis. [ABSTRACT FROM AUTHOR]

Organic solid waste treatment is crucial for enhancing environmental sustainability, promoting economic growth, and improving public health. Following our previous organic solid waste upgrading technique, a further two-step pilot-scale run, using sugarcane bagasse as the feedstock, has been successfully conducted with long-term stability. Firstly, the sugarcane bagasse was treated under mild conditions (400 °C and 1 bar of CH4), and this catalytic Methanolysis treatment resulted in a bio-oil with a yield of 60.5 wt.%. Following that, it was subjected to a catalytic Methano-Refining process (400 °C and 50 bar of CH4) to achieve high-quality renewable fuel with a liquid yield of 95.0 wt.%. Additionally, this renewable fuel can be regarded as an ideal diesel component with a high cetane number, high heating values, a low freezing point, low density and viscosity, and low oxygen, nitrogen, and sulfur contents. The successful pilot-scale catalytic upgrading of sugarcane bagasse further verified the effectiveness of this methane-assisted organic solid waste upgrading technique and confirmed the high flexibility of this innovative technology for processing a wide spectrum of agricultural and forestry residues. This study will shed light on the further valorization of organic solid waste and other carbonaceous materials. [ABSTRACT FROM AUTHOR]

Alkali-activated materials (AAMs), which are prepared by using various solid wastes as precursors and reacting with alkaline solutions, are gradually applied in the construction industry. However, not all solid waste precursors can exhibit good performance in the preparation of AAMs. To realize the effective utilization of phosphorus slag (PS) solid waste, alkali-activated PS-GBFS-FA (AAPGF) was prepared by using PS and GBFS/FA. Using different contents of GBFS/FA to replace PS, the workability performance, mechanical properties and hydration products of AAPGF were investigated. The incorporation of GBFS/FA improves the fluidity of AAPGF, but leads to slurry flash setting. When containing 30% GBFS/FA, the 28 days compressive strength of AAPGF can reach the highest 72.65 MPa. GBFS/FA increased the number of C-(A)-S-H gels, accompanied by the formation of hydrotalcite gels. In addition, GBFS/FA also transforms AAPGF hydration products from C-S-H gel to C-(N)-A-S-H and N-A-S-H gel with high degree of polymerization, and SiO4 tetrahedron is Q2 unit. GBFS/FA will significantly reduce unhydrated particles, but it will lead to uneven distribution of hydration products and produce large pores. The results of this study can provide reference value for the effective use of PS. [ABSTRACT FROM AUTHOR]

Disposal of municipal solid waste in open dumpsites remains widespread throughout the developing world. While harm to local environments and public health may seem apparent, the lack of credible estimates of damages from open dumpsites is a major reason for their continued use. This paper estimates the disamenity damages imposed by an open dumpsite in Colombo, Sri Lanka, on nearby property owners using hedonic regression methods and a novel data set collected for the purpose. We find that property values increase by 10% for every additional 100 m of distance from the edge of the dumpsite and thus provide the first credible estimate of costs imposed by open dumping in a developing country. As open dumpsites are often sited in less affluent areas, our results suggest that such sites are likely exacerbating urban inequities in urban agglomerations across the developing world. [ABSTRACT FROM AUTHOR]

Expansive clays feature high compressibility and large swelling-shrinkage potential, which may cause significant damage to the infrastructures, including pavements. This study investigates the potential use of industrial waste ash generated from municipal solid waste incineration (MSWI) as a more sustainable treatment method to treat expansive soils compared to the use of conventional coal fly ash. A series of tests was conducted to study the mechanical, durability, and environmental performance of the MSWI fly ash in comparison with the coal fly ash. The study reveals that the compressive strength and resilient modulus of 20% MSWI fly ash treated sample increased to 0.86 MPa and 213 MPa respectively, depicting an increase of 150% and 240% of the control clay specimen. Results also indicate that MSWI treated expansive clay shows better performance during the soaked California bearing ratio (CBR) testings, moisture susceptibility and cyclic wetting–drying tests compared to coal fly ash treated samples. Microlevel investigations reveal that the influence of cation exchange is more decisive in the MSWI-treated clays due to the presence of higher Ca2+ ions, during the early stages, and the influence of hydration is stronger at the later stage of stabilisation. X-ray diffraction (XRD) results show that gismondine, albite, calcite, portlandite, andradite, and ettringite are the main crystalline phases formed during the stabilization. Heavy metal concentrations after the stabilisation are within the allowable limit defined by state regulations. Applying MSWI fly ash as a ground treatment for expansive clays can reduce the consumption of natural resources, promoting a "zero landfill" policy. [ABSTRACT FROM AUTHOR]

The production of municipal solid waste (MSW) has led to an unprecedented level of environmental pollution, worsening the global challenges posed by climate change. Researchers and policymakers have recently made significant strides in the field of sustainable and renewable energy sources, which are viable from technological, environmental, and economic perspectives. Consequently, the waste-to-energy programs enhance nations' socioeconomic status while positively impacting the environment. To predict the higher heating value (HHV) of MSW fuel based on carbon, hydrogen, oxygen, nitrogen, and sulfur content, the current study introduces a Gradient Boosting Regression Tree (GBRT) model optimized with the Slime Mold Algorithm (SMA). This model was evaluated using an additional 50 data points after being trained with 202 MSW biomass data points. The performance of the model was assessed using three metrics: root mean square error (RMSE), mean absolute error (MAE), and the coefficient of determination (R2). The results indicated that our model outperformed previously developed models in terms of accuracy and reliability. Additionally, a graphical user interface (GUI) was developed to facilitate the practical application of the model, allowing users to easily input data and receive predictions on the enthalpy of the combustion of MSW fuel. [ABSTRACT FROM AUTHOR]

Industrial wastewater discharge, tainted with hazardous substances, including dyes like methylene blue (MB) from the textile sector, further emphasizes the need for water treatment to produce safe drinking water. This study explores the potential of olive mill solid waste, an abundant and cost-effective agricultural waste in Mediterranean regions, to yield high-quality activated carbon (AC) with zinc chloride activation for MB adsorption. The activation process, carried out at a modest temperature of 500 °C without the need for an inert atmosphere, resulted in AC with remarkable characteristics, boasting a substantial surface area of 1184 cm2·g−1 and a total pore volume of 0.824 cm3·g−1. Extensive characterization of the AC was carried out through a large range of surface techniques. The pH of the solution had minimal influence on MB adsorption, the maximum removal was 95%, which was under slightly acidic pH conditions (5.8), and the adsorbent dose was 0.4 g·L−1 for a 50 mg·L−1 MB concentration. Equilibrium data pertaining to MB adsorption were subjected to fitting with different models, namely Langmuir, Freundlich, and Temkin. Notably, the Langmuir model exhibited the best fit, revealing a maximum monolayer adsorption capacity of 500 mg·g−1 at 25 °C, and the adsorption kinetics closely followed a pseudo-second-order model. [ABSTRACT FROM AUTHOR]

Highlights: Data analysis revealed that an appropriate amount of BPG can enhance the mechanical properties of cementitious materials, with compressive strength increasing by an average of 7–30%. The mechanical properties and underlying mechanisms of BPG-based cementitious materials were summarized. This study analyzed the mechanisms of the conversion and utilization of elements of impurities in BPG, as well as the solidification mechanisms of hazardous elements. The mechanisms of synergistic utilization between BPG and silica–alumina-based solid waste, as well as alkaline solid waste, are summarized, showcasing innovative waste management strategies. A sustainable solution for promoting the collaborative low-carbon development of various industrial solid wastes using BPG is proposed. Industrial byproduct gypsum (BPG) is a secondary product that is mainly composed of calcium sulfate discharged during industrial production. BPG primarily consists of desulfurized gypsum, phosphogypsum, and titanium gypsum, which account for 88% of the total BPG in China. The large-scale utilization of these three types of solid waste is crucial for the safe disposal of BPG. BPG contains various impurities and harmful elements, limiting its applications. The continuous accumulation of BPG poses a serious threat to the safety of the environment. Based on a literature review (2021–2023), it was found that 52% of BPG is used in the preparation of cementitious materials, and the addition of BPG results in an average improvement of 7–30% in the mechanical properties of cementitious materials. Moreover, BPG has a positive impact on the immobilization of hazardous elements in raw materials. Therefore, the utilization of BPG in cementitious materials is beneficial for its large-scale disposal. This study primarily reviews the effects and mechanisms of BPG on the mechanical properties of cementitious materials and the solidification of hazardous elements. Most importantly, the review reveals that BPG positively influences the hydration activity of silica–alumina-based solid waste (such as steel slag and blast furnace slag) and alkaline solid waste (such as carbide slag and red mud). This improves the proportion of solid waste in cement and reduces production costs and carbon emissions. Finally, this article summarizes and proposes the application of BPG in cementitious materials. The application of BPG + silica–alumina solid waste + alkaline solid-waste-based cementitious materials is expected to realize a new type of green ecological chain for the joint utilization of multiple industrial solid wastes and to promote the low-carbon sustainable development of industrial clusters. [ABSTRACT FROM AUTHOR]

Population growth has generated an enormous increase in demand for energy and chemicals to supply goods and services and to maintain quality of life. Oil, coal, and natural gas are the primary sources of the chemicals and energy that directly impact the economy. However, the reserves of these resources are continuously reducing. New alternatives have emerged, including biotechnological tools such as microbial consortia (MC) to produce biofuels, chemicals such as organic acids, and processed foods. The diversity of MC as a biotechnological tool allows it to be used in complex substrates, opening the possibility of using other solid waste to implement consolidated bioprocesses (CPs). This review presents an overview of the uses of MC and CP for producing biofuels using different feedstocks. [ABSTRACT FROM AUTHOR]

In the present investigation, a thorough examination of waste composition was undertaken in the Tamale Metropolis, Ghana. The methodology employed was carefully designed, incorporating both commercial and residential sectors as well as various socioeconomic classes. Source-based sampling of waste materials covered a range of locations, including households, markets, hotels, and restaurants, while socioeconomic-based categorization followed the zoning of the metropolis. Waste audit sampling involved collecting a total of 90 batches of solid waste over the three-month period from August to October 2023. The primary objectives were to physically characterize the waste and evaluate its chemical properties through proximate and ultimate analysis of waste fractions, aiming to determine the waste-to-energy potential and compatibility with waste-to-energy technologies. The study revealed that the Tamale Metropolis generates 176.1 tons/day of Municipal Solid Waste (MSW) at a rate of 0.47 kg/capita/day. Organic matter constituted the majority (44.9%), followed by inert, miscellaneous, and plastic waste at 20% each. The remaining 14.3% comprised paper, metal, glass, leather, and textile components. Notably, the hospitality sector exhibited the highest organic matter content at 62.3%, contrasting with average households and markets at 44.9% and 13.1%, respectively. Moisture content ranged from 5.4% to 12.6%, volatile solids from 21.8% to 77.2%, and gross calorific values from 7.9 MJ/kg to 28.9 MJ/kg. Household waste demonstrated the highest energy content at 6693.8 kcal/kg, followed by hotels/restaurants (2003.94 kcal/kg) and markets (1883.62 kcal/kg). This study's findings offer valuable insights that can inform the development of effective policies by regulatory bodies such as the Public Utility Regulatory Commission (PURC) and the Ghana Ministry of Energy, as well as city authorities like the Tamale Metropolitan Assembly and the Environmental Protection Agency. These insights can be used to address waste and energy challenges in the metropolis. Implications: The findings reveal critical insights with substantial implications for stakeholders and regulatory bodies. It emphasizes the waste-to-energy potential of various waste fractions, highlighting the need for sustainable municipal waste management strategies. Particularly, the high organic content in the hospitality sector presents significant energy recovery opportunities. For bodies like the Public Utility Regulatory Commission and the Ghana Ministry of Energy, this data is crucial for developing policies that support waste-to-energy technologies. Additionally, the Tamale Metropolitan Assembly and the Environmental Protection Agency can use these insights to improve local waste management practices, customizing interventions to address specific sectoral waste composition. The study also underlines the importance of ongoing monitoring to ensure the effectiveness of these strategies over time. [ABSTRACT FROM AUTHOR]

Fluorine-containing silicon residue (FSR) is a solid waste that is harmful to the environment. A new alkali-free liquid accelerator based on aluminium sulfate (LAFS) was prepared using FSR. The addition of LAFS to cement mortar shortened the setting times and significantly improved the early strength. With the addition of 8% LAFS, the initial and final setting times were 2.48 min and 11.83 min, respectively, and the 1-day compressive strength was 14.6 MPa, which was 200% of that of the mortar without LAFS. The mechanism of the action of LAFS was studied using isothermal calorimetry test, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and other analytical methods. The results showed that the LAFS rapidly generated a large amount of ettringite and promoted the formation of calcium silicate hydrate in the cement paste. A conceptual model of the early hydration process of cement paste with added LAFS was established based on the analytical results. [ABSTRACT FROM AUTHOR]

Landfilled solid waste polymers were converted into high octane green fuels and hydrocarbons by a catalytic depolymerization process. Experiments were conducted in a batch catalytic reactor pressurized with methane as a co-feed. Design of Experiments (DOE) methodology was used for process optimization and parametric study. The operating conditions that maximize the liquids aromatic hydrocarbons were found using response optimizer tool. The reaction temperature and polymer to catalyst ratio (PCR) were found to have significant effects on the responses and methane pressure was not significant for yields of solids, liquids and gaseous products. However, pressurized methane facilitated dehydrocyclization reactions resulting in increased monoaromatic hydrocarbons in the final liquid products. Experiments conducted with methane feed at optimized reaction conditions resulted in 89% aromatic hydrocarbons, 8% paraffins and about 3% other hydrocarbons in liquid products. Aromatic products included benzene (6.5%), toluene (25%), xylenes (27%), ethylbenzene (4.5%), other monoaromatics (22%) and polyaromatic hydrocarbons (4%). Gaseous products contained propylene (47%) and hydrogen (23.9%). The utilization of waste polymers as feedstock materials, flare gas (methane) as a co-feed, and zeolite catalysts makes this batch zeolitic slurry process greener, resulting in green hydrocarbons and green fuels. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of Fibre-reinforced sands (FRS) has been extensively studied, presenting improved mechanical properties compared to unreinforced soils. Many models have been developed to predict its general stress-strain behaviour. However, the use of double-phase models in FRS is still incipient. Double-phase models are advantageous because they can simulate the whole FRS and the behaviour of its individual components, soil skeleton and reinforcement. This paper uses a modified model for Municipal Solid Waste to reproduce the FRS mechanical response. Introducing a new hardening parameter and a dilatant zone allowed the model to reproduce FRS dilatancy. The model's variables are easily understood, allowing the reproduction of the mechanical behaviour of FRS formed by sands with void ratios ranging from 0.610 to 0.917 and mean grain size from 0.29 to 0.83 mm. The fibres' lengths varied from 12.5 to 51 mm. The results of triaxial and hollow cylinder torsional tests under different stress paths had their main characteristics (peak strength, post-peak behaviour, dilatancy and reinforcement effectiveness) well captured by the model. Predicted and experimental FRS's deviator stress usually differ by less than 15% and the model performance is equivalent or superior to other available models, even requiring fewer input parameters. [ABSTRACT FROM AUTHOR]

One of the most important problems and the main obstacle of this process is the transformation of the complex structure of lignocellulose. One of the ways to break the lignocellulosic structure is to use suitable pretreatment compounds and nanoparticles with appropriate concentration. For this purpose, the synergistic effect of 6%NaOH pretreatment with different magnetite nanoparticle (MNP) concentrations was assessed for maximizing the biogas production. In this study, the optimal mixing ratio of MSW and SS codigestion was determined from our previous studies (MSW:SS 60:40). Application of the 6%NaOH pretreatment alone increased biogas and methane production by 24.6 and 35.4%, respectively, compared to the control. Also, the 6%NaOH pretreatment alone elevated cellulose by 85% while reducing lignin and hemicellulose by 64 and 33%, respectively. The greatest biogas and methane production was obtained in the reactor of 6%NaOH with an MNP concentration of 110 ppm, experiencing an 86 and 162% increase compared to the control. The greatest reduction in total solids and volatile solids was also obtained in this digestor by 76.6 and 79%, respectively, compared to the control reactor. [ABSTRACT FROM AUTHOR]

The unwashed alkali-treated lignocellulose can be directly enzymatically hydrolyzed and fermented via pH adjustment with acids. The use of acids would give a burden on production cost. Furfural residue (FR) which is the acidic solid waste from lignocellulose-derived furfural production process was employed in this study as a pH regulator. The corn cob-derived FR was used to adjust the pH value of alkali-treated corn stover (PCS) to 4.8 for enzymatic hydrolysis and ethanol fermentation. The unwashed PCS adjusted by FR got higher enzymatic hydrolysis efficiency (EHE) than the washed PCS samples. Meanwhile, the mixing of PCS and FR had a synergistic effect on the EHE of PCS. The fermentation of enzymatic hydrolysate from unwashed PCS-FR mixture at 20% solid concentration could attain ethanol production of 26.54 ± 0.02 mg/mL with a yield of 89.53 ± 0.08%. This work created a novel recycling way of FR as a pH regulator for improving the bioconversion of alkali-treated lignocellulose. It also provided a novel clue for the valuable valorization of wastes from corn production. [ABSTRACT FROM AUTHOR]

The study of the adhesion properties between asphalt and aggregate plays a critical role in deciphering the fracture behavior and damage characteristics in asphalt mixtures. This research is dedicated to exploring the impact of various aging behaviors on adhesion properties and the reinforcing effects of modifiers. In this context, a novel composite modifier (MPM), was synthesized from phosphogypsum whisker, derived from phosphogypsum waste. Asphalt specimens, encompassing both virgin and modified asphalt with the different dosages of MPM, were prepared under a spectrum of eight aging conditions. The mechanical properties of these specimens were meticulously analyzed using multiscale tests to assess the adhesion properties under diverse aging conditions and modifier dosages. Furthermore, the study delved into the microscopic effects of aging and modification on adhesion properties. The results highlighted that aging detrimentally impacts the adhesion properties of asphalt, with this negative effect progressively intensifying over time. In contrast, the enhancement of adhesion properties by MPM exhibited variation in accordance with its dosage. Limestone, characterized by a rougher external interface and a higher prevalence of high-valent cations, demonstrated more pronounced adhesion properties to asphalt compared to granite. The aging process introduced new diffraction patterns and characteristic peaks in the asphalt, with their intensities showing a direct correlation with the duration of aging. The MPM modification was found to effectively mitigate the deterioration in the structural stability of the virgin asphalt. Overall, this study offers comprehensive insights into the aging and modification mechanisms affecting adhesion properties between asphalt and aggregate, contributing significantly to the resource utilization of solid waste. [ABSTRACT FROM AUTHOR]