Search Results (1,734)

Municipal Solid Waste (MSW) gasification presents a promising pathway for low-carbon bio-hydrogen production. However, MSW is underrepresented as a feedstock in the gasification literature due to its heterogeneity, and fewer studies have leveraged Box–Behnken experimental design in gasification simulation studies or investigated the interaction between equivalence ratio and steam–feed ratio. This paper develops a thermodynamic equilibrium model in Aspen Plus^® (V14) to simulate oxy-steam gasification of MSW derived from the Phyllis database, with subsequent optimisation using Box–Behnken Design. Sensitivity results confirm literature trends, with hydrogen yield generally increasing with gasification temperature and steam–feed ratio up to an optimum threshold, while an increasing equivalence ratio suppresses hydrogen formation. An optimum hydrogen volume fraction of 51.77% in the syngas composition was achieved at a gasification temperature of 873 °C, equivalence ratio of 0.3, and a steam-to-feedstock ratio of 0.5. The study revealed a comparatively smooth response surface between equivalence ratio and steam–feed ratio, and a statistically insignificant effect of equivalence ratio on hydrogen formation in steam gasification. This provides new insight into gasification systems, whereby, within the investigated equivalence ratio (ER) ranges of 0.2–0.4, steam can effectively drive hydrogen-enhancing reactions, thereby reducing the relative importance of oxygen supply in oxy-steam gasification. The study could provide useful guidance on experimental design for hydrogen production through steam gasification. Full article

This study investigates whether the optimal utilization of the biomass potential contained in municipal solid waste (MSW) can support the implementation of circular economy (CE) principles and contribute to climate policy objectives, particularly the reduction in greenhouse gas (GHG) emissions in the waste management sector. The analysis evaluates whether waste-to-energy recovery can support the objectives of the European Green Deal, including a 55% reduction in GHG emissions by 2035 and the achievement of climate neutrality by 2050. The assessment was conducted for two MSW streams generated in a Polish municipality: separately collected biowaste and residual MSW remaining after meeting European reuse and recycling targets. The study summarizes the results of detailed experimental investigations of the physicochemical and fuel properties of these waste streams. Proven and commercially available energy recovery technologies, including anaerobic digestion (AD) of biowaste and incineration of residual waste, were analyzed. GHG emissions were assessed using a life cycle assessment (LCA) approach, taking into account both direct emissions and avoided emissions resulting from the substitution of conventional energy and fertilizer production. The experimental results revealed significant variability in the biodegradability and energy potential of individual biowaste fractions, with the highest biogas yields observed for kitchen waste. Residual waste exhibited a considerable calorific value and a significant share of renewable energy due to its biomass content. The results indicate that the share of renewable energy in electricity generated from waste is expected to increase from 46.1% in 2025 to 49.9% in 2040. In relation to the total electricity demand of the analyzed city, energy recovered from waste accounts for 1.8 ± 0.3% in 2025 and 1.3 ± 0.2% in 2040. Scenario-based modeling demonstrated that the target system, maximizing energy recovery from both biowaste and residual waste, achieves a consistently negative GHG emission balance throughout the analyzed period (2025–2040), ranging from −72 ± 15 kg CO₂-eq/ton in 2025, through the most favorable value of −81 ± 17 kg CO₂-eq/ton in 2035, to −57 ± 12 kg CO₂-eq/ton in 2040, expressed per ton of total managed biowaste and residual waste. Full article

The aim of this review is to provide a critical synthesis of peer-reviewed literature focusing exclusively on MSWI, rather than the broader field of Waste-to-Energy, based on a search in Scopus and a structured narrative synthesis. The methodology comprised eight Scopus queries defined for the main analytical axes of MSWI, deduplication, screening according to the established eligibility criteria, a layered corpus design, and domain-specific weighting of evidence within the framework of a structured narrative synthesis. This yielded 5435 unique records after deduplication, from which the main time window of 2010–2026 and a layer of publications from 2019 to 2026 were extracted. The review shows that the net balance of MSWI does not result from a single parameter or a single evaluation metric, but from the interplay between feedstock variability, combustion management, air pollution control (APC) configuration, residue management, and the utilisation of recovered heat and energy. Modern APC systems have reduced stack emissions, but do not eliminate the significance of transient states or the transfer of pollutants to fly ash and APC residues. Bottom ash exhibits conditional potential for material and metal recovery, whilst fly ash and APC residues remain the main constraint on recovery pathways. Environmental, climatic, health and economic assessments remain highly sensitive to system boundaries, functional units, counterfactual scenarios, the local energy mix, the quality of exposure reconstruction and integration with district heating. The added value of the review lies in maintaining MSWI as the sole analytical core and integrating the process, emissions, residues and system assessments within a single interpretative framework focused on comparability, trade-offs and the MSWI system balance. Full article

Municipal solid waste incineration fly ash (MSWI FA) represents a significant environmental challenge due to its high content of toxic heavy metal (HM) and large-scale generation. This study demonstrates the feasibility pathway for converting hazardous MSWI FA into well-crystallized layered double hydroxide nanosheets (LDH-FA). Sodium dimethyl dithiocarbamate (SDD) was incorporated as a chelating stabilizer to enable synergistic HM immobilization during acid leaching and crystallization. High-resolution transmission electron microscopy (HRTEM) confirmed the characteristic two-dimensional nanosheet morphology with interlayer spacings consistent with LDH structures, while elemental mapping revealed homogeneous distribution of Pb and Zn within the nanosheet matrix. SDD dosages higher than 1.0 wt% effectively suppressed HM leaching, and Pb concentrations were controlled below 0.1 mg/L and Zn maintained at minimal levels. BCR sequential extraction analysis further demonstrated that SDD treatment effectively transformed HMs from bioavailable acid-soluble fractions to stable forms. This investigation establishes an innovative approach to MSWI FA resource utilization and provides mechanistic insights into HM stabilization within LDH nanostructures, offering a scientific basis for safer applications of waste-derived nanomaterials. Full article

The municipal solid waste incineration (MSWI) process plays a vital role in promoting ecological civilization and sustainable development. Accurate multi-step CO₂ prediction in MSWI is particularly difficult due to complex combustion dynamics and highly non-stationary emission patterns, with current models often failing to capture both linear and nonlinear relationships effectively. To address these limitations, this study proposes a novel hybrid approach combining autoregressive integrated moving average (ARIMA) and long short-term memory (LSTM) models, optimized through Bayesian optimization (BO), chosen for its sample efficiency and ability to handle noisy objective functions in high-dimensional parameter spaces. This method first defines the search space and acquisition function and then integrates the predicted values of the ARIMA linear model and the LSTM nonlinear model to construct the objective function and finally obtains the optimal combination of hyperparameters. Based on the measured data of a MSWI power plant in Beijing, the verification shows that the RMSE of the model is reduced to 0.1856 and the MAE is reduced to 0.1453, which are reduced by 10.3% and 11.9%, respectively, compared with the baseline model LSTM. This hybrid approach to BO proved to be particularly effective for MSWI plants with variable waste composition and frequent operational changes, and for modeling data containing both linear and nonlinear mappings. The framework’s generalizability suggests promising applications for other environmental prediction tasks requiring combined linear-nonlinear modeling, while future work could explore its extension to multi-pollutant forecasting systems and intelligent emission reduction control. Full article

This review evaluates pretreatment strategies for blending the organic fraction of municipal solid waste (OFMSW) with agricultural residues to recover fermentable sugars. Three mechanistic benefits have been hypothesized for such blends: ash-mineral pH buffering, endogenous protein reduction of non-productive cellulase–lignin binding, and inhibitor dilution. These mechanisms are inferred from analogous lignocellulosic systems rather than measured directly in OFMSW–agricultural residue combinations, and their translation into saccharification gains remains substrate- and pretreatment-specific. A synergy index framework with a four-tier classification (true synergy, additive, substitution, and process complementarity) is applied to reclassify the available evidence, alongside an assessment of pretreatment chemistry, enzymatic hydrolysis outcomes, and techno-economic feasibility. Integrated sequential pretreatment, particularly acid-catalyzed steam explosion and deacetylation with mechanical refining, proved most robust for heterogeneous feeds. The strongest Tier I synergy is found for SO₂-catalyzed steam explosion of hybrid poplar–wheat straw (SI 1.29–1.33; 22% monomeric sugar gain). OFMSW combined with organosolv beechwood cellulose at 35–45% OFMSW reached 58–68% saccharification (44–46 g sugar L⁻¹), a Tier III–IV outcome. Matched-control saccharification data for OFMSW–agricultural residue blends specifically have not been reported. Co-processing corn stover with wet organic waste reduced CO₂ mitigation cost from $236 to $67 per ton CO₂-eq under bio-CNG upgrading. Formal synergy quantification, blend-specific inhibitor profiling, and high-solids process intensification are the central prerequisites for commercial translation. Full article

The transition toward renewable energy sources has become a critical global objective. For developing nations facing the dual challenges of inefficient waste management and limited energy access, waste-to-energy (WTE) technologies offer a transformative solution to mitigate environmental concerns while enhancing power grid stability. This paper presents a detailed performance analysis of a proposed WTE thermal power plant for Dire Dawa City, Ethiopia, utilizing municipal solid waste (MSW) as a sustainable feedstock. The primary objective of this study is to estimate the power generation potential of the city’s MSW through thermal incineration integrated with a Rankine Vapor Cycle. Field data collection reveals that Dire Dawa City produces an average of 237.2 tons of waste daily, with a per capita generation rate of 0.49 kg. Laboratory characterization indicates that the waste possesses high energy potential, featuring an average calorific value of 18.20 MJ/kg (18.20 × 10³ kJ/kg), a volatile matter content of 73.50%, and fixed carbon at 19.18%. Thermodynamic modeling and energy-flow simulations demonstrate that the facility can achieve a power output ranging from 7.64 MW to 22.80 MW, providing a nearly constant total energy yield of approximately 183,360 kWh per day. These results confirm that Dire Dawa City’s waste stream is a potent strategic resource for renewable energy. Ultimately, this research provides a technical roadmap for stakeholders, facilitating informed investment decisions and resource planning to ensure the successful implementation of sustainable thermal energy infrastructure in the region. Full article

A quaternary solid-waste-based binder was prepared from low-titanium slag, municipal solid waste incineration (MSWI) fly ash, steel slag, and flue-gas desulfurization gypsum (FGDG) to clarify the activating effect of MSWI fly ash on low-titanium slag and its influence on hydrate evolution. Unlike conventional solid-waste-based binders in which MSWI fly ash is mainly regarded as a hazardous residue requiring stabilization, this study demonstrates its specific role as a Ca-rich alkaline activator for promoting low-titanium slag depolymerization and coordinated hydrate formation. The results showed that the compressive strength first increased and then decreased with increasing MSWI fly ash content. Considering both strength development and MSWI fly ash utilization, the optimum mixture was identified as low-titanium slag:MSWI fly ash:steel slag:FGDG = 43.0:17.2:25.8:14.0, with compressive strengths of 9.51 and 46.32 MPa at 3 and 90 d, respectively. These values corresponded to 5.66 and 1.04 times those of the reference mixture without MSWI fly ash, respectively. Ettringite and C-(A)-S-H gel were the main strength-contributing hydration products, while Friedel’s salt was identified as a chloride-bearing AFm phase. Moderate MSWI fly ash addition promoted alkaline activation and low-titanium slag depolymerization, leading to increased formation of ettringite, C-(A)-S-H gel, and Friedel’s salt, which contributed to improved compressive strength. In contrast, excessive MSWI fly ash disturbed the Ca-Si-Al balance and inhibited effective hydrate formation. These results demonstrate that MSWI fly ash can serve as an effective Ca-rich activator for low-titanium-slag-based low-carbon cementitious materials and provide a feasible route for the synergistic utilization of multiple solid wastes. Full article

Sustainable phosphorus (P) management in agriculture requires a circular economy approach through the use of so-called bio-based fertilizers (BBFs). The properties of BBFs vary widely depending on raw materials and production processes. However, it is still unknown how these properties, and particularly the dominant P compounds determine not only the efficiency of BBFs in supplying P to crops, but also their effects on soil functioning and crop quality. This study aimed to evaluate the efficiency of a representative set of BBFs, and relate this efficiency to their composition and dominant P compounds. To this end, 14 BBFs were studied: four from water purification (struvite, vivianite, and sewage sludge with and without composting), four composts (municipal solid waste (MSW), vineyard residues, and two using olive husks), three vermicomposts (two homemade and one commercial), fish meal, digestate, and a commercial organic fertilizer. Phosphorus forms in BBFs were determined using ³¹P nuclear magnetic resonance spectroscopy (P-NMR). The BBFs were compared to a single superphosphate (SSP) in a pot experiment growing wheat in two different alkaline soils, one rich in iron (Fe) oxides and one rich in carbonates. The effects on critical elements in grain [magnesium, Fe, zinc (Zn), manganese, and copper] and enzyme activities related to soil functioning and P cycling were also assessed. The dominant P compound in the BBFs was orthophosphate (73.8–89.5% of the total P in the NaOH–EDTA extracts). The MSW had the highest polyphosphate content (4.1%), a complex inorganic P compound. The organic P content ranged from 9.2% (fish meal) to 25.5% (Moge). Sewage sludge and composted sludge contributed high levels of phosphonates (4.1 and 5.6% of extracted P). The most abundant organic P compound class was inositol hexakisphosphates (IHPs), and myo-IHP (phytate) was the dominant IHP stereoisomer (1.2–6.4%) followed by D-chiro-IHP and scyllo-IHP. Plant dry matter and grain yield with most BBFs were not significantly different from that of SSP in both soils, likely due to the high concentrations of phosphate in relatively soluble forms in most of the BBFs. Vivianite and sewage sludge resulted in significantly higher grain yield than SSP (43% and 40%, respectively) in the carbonate-rich soil, likely due to progressive phosphate dissolution, which decreased the precipitation rate of insoluble calcium (Ca) phosphates. The highest P recoveries were obtained with horse manure vermicompost (65% and 15% higher than SSP in the Fe oxide-rich and in the carbonate-rich soil, respectively), partially attributed to the decreased precipitation rate of insoluble Ca phosphates with the added organic matter. Some BBFs increased micronutrient concentrations in grains and most decreased the P-to-Zn ratio relative to SSP. Overall, phosphatase and β-glucosidase activities increased with carbon-rich BBFs. Most of the studied BBFs could effectively replace fertilizers from non-renewable sources, in some cases with better crop P recoveries. Furthermore, some BBFs could provide additional benefits to grain quality, in terms of micronutrient supply for humans, and soil functioning. Full article

Municipal solid waste landfills may remain sources of environmental concern long after closure because heavy metals can persist in soils and affect ecosystem recovery. This study presents an integrated assessment of a closed municipal solid waste landfill in Kokshetau, Northern Kazakhstan, by combining field-based soil geochemical analysis with remote sensing monitoring of vegetation dynamics. A radial-gradient sampling design was used to characterize spatial patterns of contamination and to distinguish zones with different levels of anthropogenic impact. The results showed a clear concentration of heavy metals, particularly Zn and Pb, in the central part of the landfill, where integrated pollution and ecological risk indices indicated the highest levels of technogenic pressure. Time-series analysis of Landsat-derived vegetation indices for 2017–2025 revealed poorer vegetation condition in the most contaminated areas, with NDVI and EVI values increasing toward the landfill periphery. The observed negative association between vegetation indices and ecological risk suggests that remote sensing indicators can provide useful information on the ecological condition of closed landfill sites, although they should be interpreted together with field measurements. The novelty of this study lies in the combined use of geochemical contamination indices and long-term vegetation-index monitoring to assess post-closure landfill conditions in an arid continental region of Central Asia, where such integrated studies remain limited. The findings highlight the persistence of environmental risks after landfill closure and support the use of vegetation indices as non-invasive tools for monitoring rehabilitation and prioritizing further field investigations. Full article

Achieving a circular and climate-neutral bioeconomy by 2050 requires not only high-quality recycling but also the large-scale integration of renewable carbon from biomass and atmospheric CO₂ into material systems. Plastics represent the world’s largest and most rapidly growing carbon sink, positioning them as a critical intervention point for replacing fossil-based feedstocks with renewable alternatives. Because plastic packaging is one of the most visible material streams encountered by consumers in daily life, a transition toward sustainable, recyclable bioplastics has the potential to deliver both meaningful environmental benefits and strong societal impact, accelerating public awareness and acceptance of renewable carbon solutions. Poly(ethylene furanoate) (PEF)—a fully bio-based polyester synthesized from plant-derived 2,5-furandicarboxylic acid (FDCA) and monoethylene glycol (MEG)—offers a promising pathway toward more sustainable packaging due to its superior mechanical strength and gas-barrier performance relative to polyethylene terephthalate (PET). This study presents a cradle to grave life cycle assessment (LCA) of PEF resin production and PEF bottle applications, using industrially relevant, at-scale process data covering biomass feedstock conversion, polymer synthesis, packaging manufacture, use phase, and end of life. Bottle applications were selected as a focal point due to their technical maturity, commercial relevance, and suitability for direct comparison with incumbent PET systems. The results indicate that PEF can reduce greenhouse gas emissions by up to 71% and fossil resource depletion by 26% compared to PET at the resin level when biogenic carbon uptake is included. Moreover, the material’s enhanced functional properties enable lightweight, recyclable bottle designs with carbon footprint reductions of up to 88% for 500 mL formats under a baseline recycling rate scenario of 72%, with the remaining share directed to municipal solid-waste incineration with energy recovery. Sensitivity analyses reveal that virgin PEF maintains environmental advantages over PET even when PET incorporates high levels of recycled content, highlighting the complementary roles of renewable carbon and circular material strategies. Prospective scenario modeling underscores the importance of sustainable feedstock selection and process electrification, with sucrose-based routes offering the largest potential for further decarbonization. Overall, the findings demonstrate that PEF is a scalable biopolymer capable of delivering substantial climate benefits while supporting circularity objectives. By targeting a highly visible consumer application—plastic packaging—this transition amplifies the societal impact of adopting renewable carbon materials. The study provides actionable insights for policymakers, industry stakeholders, and sustainability practitioners working to advance a more resilient, renewable, and consumer-recognizable plastics economy. Full article

Sustainable municipal solid waste (MSW) treatment in rapidly urbanizing secondary cities requires evidence-based, district-level prioritization of technologies. We integrate GIS hotspot mapping, Random Forest, and AnyLogic System Dynamics into a decision-support framework and apply it to Shymkent, Kazakhstan (population 1.19 million; ≈301,400 tonnes of MSW in 2025). This is the first application of such a framework to MSW management in a Kazakhstani secondary city and, to our knowledge, the first regional application across Central Asia; the integration concept has prior precedents in Latin American, South Asian, and East Asian metropolitan studies, and the present contribution lies in empirical calibration to a Central Asian upper-middle-income context using 2015–2025 morphological audits, air-quality and soil monitoring, and Sentinel-2 NDVI. Random Forest (n = 80, 9 predictors) achieved R² = 0.976 ± 0.011 under 5-fold cross-validation; a complementary GroupKFold protocol confirms the model is Shymkent-calibrated while the methodology remains transferable. AnyLogic simulation shows an Infrastructure/Waste-to-Energy pathway reduces the 2030 annual landfilled volume to ≈201 kt, environmental risk by 70%, and methane emissions by 86% (≈270 kt CO₂-eq/year) relative to the Inertial baseline. The principal deliverable is a District × Technology × Phase prioritization matrix for sequencing sustainable investment under realistic budget constraints. Full article

The geographic and economic contexts play a major role in decision-making when it comes to municipal solid waste management. In the present study, simulations are carried out using the Waste and Resource Assessment Tool for the Environment (WRATE) software academic version 3.0.1, based on the Ecoinvent database (version 2) to assess the greenhouse gas emissions released by 1 ton of municipal solid waste with a typical composition characterizing upper middle-income countries, with an organic fraction of approximately 50% by weight. The variation over time (2000 to 2022) with no intended transformation in the management strategy is first analyzed, then several transformations are applied by varying the waste management routes (open dumping, landfilling, recycling and composting) as well as the energy recovery integration. The results are then discussed based on the waste categories and the performed operations (landfilling, recycling, transportation, treatment and recovery). The results revealed that the most promising scenario includes limited open dumping that does not exceed 10%, landfilling with at least 20% energy recovery, and major fractions addressed to composting and recycling. Overall, this scenario returns a negative carbon footprint with a value of approximately−0.35 tons of CO₂-Eq/ton of MSW. Results are mostly applicable to countries with similar waste composition and infrastructure levels; preconditions include source segregation, compost markets, and landfill gas infrastructure. Full article

This study presents a comprehensive assessment of high-temperature performance, economic viability, and environmental sustainability of alkali-activated slag paste (AASB) incorporating municipal solid waste incineration bottom ash (MSWI-BA). The research systematically evaluates the effects of MSWI-BA content (0–12%), alkali content (2–6% Na₂O equivalent), water glass modulus (Ms = 0.75–1.75), and activator type on key performance metrics, both resource recovery and carbon reduction goals. Results show that the optimized formulation (6% MSWI-BA, 4% Na₂O, Ms = 1.5) achieves superior high-temperature resilience, retaining 76% of its initial compressive strength after 800 °C exposure—a stark contrast to OPC, which undergoes near-complete strength loss. Economic analysis reveals that while MSWI-BA offers an 88% reduction in raw precursor cost, the optimized AASB incurs a modest 3.7% total material cost premium over OPC, which is offset by its long-term sustainability benefits. Furthermore, a life-cycle assessment demonstrates that AASB has a 66.95% lower carbon footprint than OPC. Full article