Environmental and Earth Sciences

Abstract: This study evaluates the potential of solid digestate as a feedstock for granulated organo-mineral fertilizers (OMF). The aim was to improve nutrient density, safety, and soil conditioning properties while supporting circular bioeconomy principles. Digestate was enriched with ammonium sulfate, monoammonium phosphate, and potassium chloride to produce OMF. The granules were analyzed for nutrient content, heavy metals, and functional group stabilization (FTIR). Soil incubation tests assessed the cation exchange capacity (CEC), while spring barley pot experiments evaluated biomass production and nutrient uptake. OMF granules achieved nutrient levels of N = 5.0%, P2O5 = 5.9%, and K2O = 4.7%, with dry matter of 95.9% and ash content of 32.4%. Heavy metals (Cd < 0.5, Pb < 5, As < 1.0 mg/kg) were well below EU safety thresholds. Compared to digestate pellets (C:N ≈20:1), OMF (C:N ≈7.8:1) showed faster mineralization. Soil incubation revealed increased CEC from 26.1 to 32.1 cmol(+)/kg. Barley biomass rose by 6.8–9.6%, with P and K accumulation strongly correlated with growth (r = 0.960 and r = 0.828). Uptake efficiencies reached 14.6% for P2O5 and 86.9% for K2O. Digestate valorization through organo-mineral granulation provides a safe and effective fertilizer pathway that enhances soil fertility, nutrient efficiency, and crop performance, while contributing to sustainable circular agriculture.

Abstract: Between 1943 and 1989, the Hanford Nuclear Site produced weapons-grade plutonium and accumulated 212,000 cubic meters of mixed radioactive and hazardous chemical waste, stored in 177 aging underground tanks. It is estimated that 90% of this waste is “Low Activity Waste” after the cesium, strontium, and transuranics are removed. In late 2025, the Direct Feed Low Activity Waste facility began vitrification, which involves mixing liquid waste with molten glass at 1150 °C to destroy hazardous organic chemicals, at an average rate of 15 metric tons per day. Maintaining heat in the two 300-ton melters requires about 200,000 megawatt-hours of electricity each year. Over 40 years, this electricity use results in about 3,000,000 tonnes of carbon dioxide emissions. To mitigate this carbon footprint, a significant portion of the waste could be “grouted” with a mixture of Portland cement, granulated slag, fly ash, and batch-specific chemicals. Vitrifying LAW has a carbon footprint of about 32 tCO₂e per cubic meter (m³), whereas grouting LAW and shipping it out-of-state by truck involves about 6 tCO₂e/m³, and shipping it by rail involves about 2.5 tCO2e/m3. Adding a rail spur to a grouting facility is key to Hanford’s net-zero approach.

Abstract: The rapid global expansion of photovoltaic (PV) systems, driven by rising energy demand, is expected to generate substantial module waste at end-of-life, with global PV waste projected to exceed 4 million tonnes by 2030, 50 million by 2040, and 200 million tonnes by 2050. Based on 102 publications identified through Scopus, Web of Science, Google Scholar, and IEEE Xplore databases, this review provides a comparative, literature-based assessment of recycling, second-life applications, and disposal as end-of-life (EoL) management strategies for PV modules, examining the relationship between module structure, waste management pathways, material recovery potential, and the technical and economic limitations of current practices. Recycling offers clear environmental benefits but remains economically constrained in many scenarios by high process costs and the complexity of separating laminated module structures. Second-life application emerges as a complementary strategy, delaying the premature entry of modules retaining residual functionality into the waste stream and enhancing resource efficiency. Nevertheless, landfilling continues to account for the majority of global PV waste despite the availability of more sustainable alternatives, revealing a marked gap between technical potential and field-level practice. Overall, no single approach is sufficient; effective PV waste management requires an integrated strategy combining recycling, second-life applications, and disposal in line with circular economy principles.

Abstract: Landfilling doesn’t eliminate waste. It is only a mechanism for temporarily storing waste, which means environmental issues continue to persist. Waste in landfills can pose serious risks to the environment and human health, including the emission of potent greenhouse gases such as methane, foul odours, leachate-contaminated groundwater, and the loss of circulating resources vital to a sustainable economy. Landfills are still being created globally, in addition to those that already exist. This alone is a valid reason for us to explore how we manage them, since their impact, both short and long term, can potentially generate a multitude of adverse consequences. Landfill mining (LFM) offers a method to reduce the risk of various contaminants entering the environment from landfills and to recover useful materials from discarded and buried waste. By shifting the view of landfills from waste storage to a source of resources, LFM can help reduce long-term environmental problems, support the circular economy, and change how society manages buried waste. The concept of Landfill Mining (LFM) has emerged as a possible solution to increasing issues in waste management, such as limited landfill space, pollution, and the need to rehabilitate sites. Early LFM projects mainly recovered small quantities of materials, such as soil and waste fuels, but encountered many obstacles, including technological constraints, high costs, and strict regulations, which made LFM less common. Recent research and technological advances suggest that LFM could achieve much more if the right conditions are met. With active enforcement of policies such as extended producer responsibility (EPR), government oversight, and improved material processing, LFM could scale to industrial levels, helping recover more resources and manage legacy waste. Clear guidelines for responsible waste management will be vital for ensuring this over the long term. LFM is not just a way to create value from waste; it also helps implement circular economy principles. This paper describes LFM as a form of ‘retrospective circular economy.’ LFM can transform old landfills into urban mines, converting buried waste into useful raw materials and helping society move towards sustainability.

Abstract: Waste generation continues to increase despite advances in recycling, waste valorization, and circular economy policies. Existing explanations commonly emphasize technological, economic, or governance factors, yet provide limited insight into why waste persists even when circularity becomes increasingly embedded in policy discourse and institutional frameworks.This article introduces transition decoupling as an interpretative concept for understanding why waste persists despite growing commitments to circular economy transitions. To examine this phenomenon, the article develops the Neuroecology of Waste as a framework linking cognitive-discursive, institutional, and material dimensions of urban systems.The article develops the concept of transition decoupling to explain how cognitive-discursive change, institutional adaptation, and material reconfiguration may evolve at different rates during circular economy transitions. When these dimensions become misaligned, circular narratives and institutional reforms may advance while disposal-oriented material configurations remain dominant.The framework is illustrated through a comparative assessment of three Latin American metropolitan systems: Mexico City, Bogotá, and Santiago. The analysis reveals strong cognitive-discursive and institutional commitments to circularity across all cases, while material transformation remains partial or limited. Mexico City was classified as a case of Transitional Coupling, whereas Bogotá and Santiago were classified as Decoupled Transitions.The findings suggest that waste persistence may be interpreted as a consequence of unevenly synchronized transition processes rather than simply the absence of transition itself, providing empirical support for the concept of transition decoupling.

Abstract: The incorporation of recycled coarse aggregates (RCA) derived from dispersed waste concrete into lining concrete for underground engineering presents a potential strategy to reduce primary resource depletion. However, the actual environmental benefits of this approach are highly contingent upon logistical factors, such as transport distances, and the mix design adjustments necessary to compensate for RCA quality variations. In this study, a cradle-to-gate life cycle assessment (LCA) was conducted for C30/37 underground lining concrete to evaluate the combined effects of RCA replacement ratio, waste concrete transport distance, and cement-compensation assumptions. Literature-based RCA properties-including density, water absorption, and mechanical performance indicators-were employed to support four cement-compensation scenarios (0%, 5%, 10%, and 15%) at a fixed 30% RCA replacement rate. The results reveal that cement production accounts for over 80% of the total global warming potential (GWP). Under an equal cement content scenario, each 10% substitution of natural coarse aggregate with RCA reduces aggregate-related GWP by approximately 0.233 kg CO2 eq/m³. However, the total GWP of the CC0 scenario is only 0.18% lower than that of conventional concrete. In contrast, cement-compensation levels of 5%, 10%, and 15% increase the GWP to 455.3, 474.7, and 494.1kg CO2eq/m3, which are 4.26%, 8.72%, and 13.17% higher than conventional concrete, respectively. The previously identified critical transport distance of 26.04 km is therefore specifically applicable only to the equal-cement CC0 aggregate-substitution scenario. These findings demonstrate that the environmental feasibility of RCA-based lining concrete is jointly governed by the quality of the recycled material, the additional cement demand, and regional transport conditions. The outcomes provide a quantitative foundation for decision-making in the production and environmental performance evaluation of underground lining concrete, particularly in the context of extreme environments, where material reliability and resource security are of paramount importance.

Abstract: The aim of this research is to analyse how small and medium-sized construction companies in Catalonia are advancing towards a circular economy model through material recycling, energy efficiency and passive building design, in line with the 2030 Agenda and the European Green Deal. The exploratory study focuses on case studies of companies, including those certified with the RECONS (acronym for Environmental Responsibility in Construction in Catalonia) environmental label, identifying strategies to reduce the carbon footprint by valorising construction and demolition waste, adopting Energy Saving Certificates (ESCs), and implementing passive standards such as Passivhaus in a Mediterranean climate. A literature review is combined with empirical analysis to assess regulatory, technological and market barriers, as well as existing economic incentives. The findings indicate that the use of recycled aggregates and passive construction solutions enables significant reductions in energy consumption and emissions, while ESCs and environmental labels act as key levers to accelerate the transition towards a more sustainable construction sector aligned with the Sustainable Development Goals.

Abstract: Whether economic growth decouples from municipal solid waste (MSW) generation in upper-middle-income economies remains contested. We test the Waste Kuznets Curve and a disposal-to-recovery substitution effect using a 13-year panel of 1,101 Colombian municipalities, combining step-wise fixed-effects models with a non-parametric generalised additive model (GAM), a spatial autoregressive (SAR) check, and a selection-aware recovery model. We find no evidence of income-driven decoupling in landfilling. Once urban density and demographic structure are controlled, the income terms lose significance, the non-parametric estimate is predominantly monotonic, and density emerges as the main structural driver. Material recovery grows faster than disposal with income (relative substitution), but this signal is concentrated where recovery is measured—only 27% of municipalities report it, and coverage falls from 86% in metropolitan tiers to 19% in the rural periphery—so that once selection is corrected the recovery elasticity falls from about 5.9 to a non-significant 1.3. Rather than spontaneous decoupling, Colombia exhibits persistent coupling alongside an institutionally engineered, spatially unequal recovery capacity. Achieving SDG 12 therefore requires stratified policies that mandate consumption reduction in mature urban economies while subsidising shared circular infrastructure for historically neglected rural jurisdictions.

Abstract: Household food waste remains a huge challenge for solid waste management in municipalities worldwide, especially in the Global South. Existing studies that measured food waste (FW) in cities are scarce, have limited geographic scope, and have limited timeframes. In that direction, the current investigation provides data on the FW composition of nine regions of the municipality of Rio de Janeiro (Brazil), based on a three-year sampling across 155 neighborhoods. Waste samples were collected from 2021 to 2023. In total, about 24,038 kg (fresh weight) were analyzed. Results showed that FW accounts for an average of 47.7±1.9% of household waste in the study period. The FW composition in the city of Rio de Janeiro ranged from 60.3 – 76.5% for fruits, vegetables, and salads, 15.0 – 25.1% for fine aggregate (small-sized food residues < 2.54 cm, like rice, beans, grains, and fragmented food particles), and 3.2 – 5.8% for proteins (discarded animal-based protein foods like chicken and meat). The chi-square good-ness-of-fit test was applied to evaluate whether the FW composition in each of the nine regions differed from the mean FW composition of the Rio de Janeiro municipality. The findings revealed statistically significant differences (p-value < 0.05) in the average FW fractions in specific regions and years compared with the city’s average composition. Thus, one of the key takeaways of this investigation was that the percentages of discharged food waste fractions vary over time and across locations, even within the same municipality. The present research took a first step toward understanding the food waste problem in Rio de Janeiro (Brazil) and underscores the importance of monitoring food waste data to guide the development of locally specific strategies for sustainable urban food systems, including waste prevention, recycling, and food recovery.

Abstract: This study uses causal loop diagram (CLD) to explore the system dynamics of urban waste management analysing the interdependencies among waste generation, operational efficiencies, governance, public behaviour, and environmental outcomes. The model identifies key reinforcing and balancing feedback loops that drive system performance, including data–policy–performance, awareness–segregation, and technology–innovation dynamics. It also highlights critical constraints such as collection inefficiencies under system overload and the adverse effects of inadequate monitoring and data availability. Findings suggest that strengthening monitoring systems, enhancing public awareness, and investing in technological innovation, concomitantly, can create reinforcing improvements across the waste management system. On the other hand, weak governance and data gaps undermine system responsiveness and environmental outcomes. The study contributes to policy design by providing a holistic framework for understanding leverage points that can improve sustainability and resilience in waste management systems.

Abstract: This study investigates the potential for recovering valuable minerals from feldspar tailings generated during industrial processing and commonly discarded as waste, causing both economic losses and environmental concerns. A hydrocyclone overflow sample obtained from a feldspar processing plant in the Muğla region of Türkiye was characterized and evaluated for the production of a marketable feldspar concentrate by flotation. Bulk and selective reverse flotation tests were performed using Denver and TK Lab flotation cells incorporating different impeller–stator configurations to evaluate the combined effects of reagent chemistry, flotation cell hydrodynamics, and bubble characteristics on flotation performance. The Sauter mean bubble diameter (d₃₂) was measured under both two-phase and three-phase conditions to characterize bubble size. Compared with the conventional plant reagent scheme (Derna-7 and Der A4), the sequential flotation scheme employing sulfonate collectors (R801–R825) for Fe–Ti-bearing minerals followed by the amine collector DAHC for mica significantly improved impurity rejection. The highest concentrate quality was achieved in the TK Lab Cell, producing a feldspar concentrate containing as low as 0.49% Fe₂O₃ while maintaining a total alkali content of 9.57%, satisfying the Fe₂O₃ requirement for second-grade ceramic applications. Despite producing larger bubbles than the Denver Cell, the TK Lab Cell exhibited superior rejection of Fe–Ti-bearing minerals. The consistently larger bubbles generated by the TK Lab Cell, irrespective of the reagent scheme employed, indicate that the different impeller–stator configurations played a key role in governing bubble generation and gas dispersion, while reagent chemistry primarily modified bubble characteristics within the hydrodynamic environment established by each flotation cell. The results demonstrate that flotation performance is governed by the combined effects of reagent chemistry, flotation cell hydrodynamics, and bubble characteristics, providing new insights into the sustainable valorization of feldspar processing tailings.

Abstract: Implementation of circular solutions in place of single-use plastic products requires stronger alliance between science and private sector. To investigate benefits of knowledge and strategy co-creation, this study applies common-pool resource theory in the design of a serious game. A total of 188 Polish biology and geography undergraduate students (researchers-to-be), divided into two teams, representing science and business actors with shared goals, participated in 20 facilitated game sessions. Two versions of the game were assessed – with a separation of the teams or with the personnel exchange. The results of the games were analyzed in relation to the structure of the shared social values as a differentiating co-factor. Science–business collaboration and environmental attitudes were evaluated with pre/post-questionnaires to assess the game’s potential as a science communication and educational tool. Results suggest that the successful resolution of the presented common-pool resource dilemma correlates with the introduced collaboration and the self-transcendence values. As hypothesized, we observed desirable changes in participants’ attitudes after the game sessions. Further investigation of gaming as a science communication tool and its long-term effects is recommended to facilitate implementation of the knowledge co-creation principles in practice.

Abstract: Oil contamination of soils in arid regions of Kazakhstan is a critical environmental problem, as extreme temperatures, low humidity and salinity limit traditional bioremediation. A pilot-scale 45-day field experiment at the Karazhanbas oil field (Mangistau Region, Kazakhstan) provided a first field validation of an adsorption-immobilisation bioremediation technology. A consortium of Rhodococcus erythropolis AT7 and Dietzia maris 22K was immobilised on buckwheat and rice husk carriers. Four treatments were tested on 1 × 1 m plots (initial petroleum products 3725 mg/kg): the consortium immobilised on buckwheat husks, on rice husks, free cells, and an untreated control. Petroleum products were measured by FTIR spectroscopy on days 0, 15, 30 and 45. The buckwheat husk variant showed the highest efficiency — 94.0 ± 0.5% (3725 to 223 ± 18 mg/kg) — 1.6 times higher than rice husk (57.9%) and 1.7 times higher than free cells at the standard dose (54.6%). Degradation followed first-order kinetics (k = 0.0455 day⁻¹; t_1/2 = 15.3 days), and hydrocarbon-oxidising microorganisms reached 10⁸ CFU/g. The superiority of buckwheat husks is primarily attributable to their lower lignin content and more favourable structural and nutritional properties, with the antioxidant rutin as a plausible additional factor. These pilot results provide a basis for larger-scale validation in Western Kazakhstan.

Abstract: Digital twins offer significant potential for operationalizing a circular economy at the municipal level. This study aims to propose a business model framework that optimizes the circular management of municipal solid waste (MSW) by leveraging the concept of "Co-creative Digital Process Twins." The methodology was structured around two primary axes: first, a critical literature review conducted via the PRISMA-ScR protocol to identify process architectures and existing research gaps in digital process twin development; and second, a theoretical-practical integration using the Business Model Canvas tool, grounded in the paradigms of the circular economy and participatory design, applied to a case study in the municipality of Progreso, Hidalgo, Mexico. Our findings reveal a significant bias in the current state of the art: existing digital twin applications are predominantly industrial and notably lack social inclusion mechanisms. In response, this paper presents a multidimensional business model that integrates key social actors into the digital ecosystem, establishing an architecture explicitly designed to maximize material recovery rates. Conclusively, the adoption of co-creative digital process twins provides a robust socio-technical infrastructure that not only simulates and optimizes the waste value chain but also fosters social inclusion, thereby catalyzing the transition toward a genuinely circular municipal economy.

Abstract: To improve biowaste recycling efficiency, this study evaluated the effect of a low-dose grass amendment (BG) on the composting performance of biowaste (B) in a pilot-scale two-stage system. The incorporation of a low-dose grass amendment increased feedstock porosity, thereby enhancing O2 diffusion and reducing the formation of anaerobic micro-zones during composting. Consequently. BG composting proceeded more intensively than with B, with higher initial OM degradation rates in both kinetic phases (BG: 19.03 and 7.32 g/(kg DM·d) versus B: 11.42 and 0.77 g/(kg DM·d)). Enhanced mineralization in the amended composting also promoted a more intensive thermophilic phase (BG: 60°C for 12-day; B: 55°C for 14-day). After 40 days in the bioreactor, the relative volume decreased to 50% and 58.2% of the initial volume for composted BG and B, respectively. Overall mass reductions in two-stage composting were 39.20% and 50.76%, respectively. Both mature composts exhibited high stability with AT4 values of 7.6 and 5.6 mg O2/g DM for B and BG, respectively. Phytotoxicity tests showed no inhibitory effects at application rates of 1–5%, with germination indices exceeding 80%, confirming compost maturity and a stimulatory effect on seed growth. Overall, co-composting of biowaste with seasonal grass improves composting performance and process efficiency.

Abstract: The sustainable management of biogas production digestate and lignocellulosic green waste remains a major challenge in circular bioeconomy systems. This study evaluated the feasibility and effectiveness of co-composting liquid digestate with woody pruning residues as an integrated strategy for nitrogen conservation, and enhanced composting performance. Experiments were conducted at both laboratory and intermediate scales using shredded residues from several tree species soaked in digestate or nitrogen solutions prior to aerobic incubation or open-pile composting. Nitrogen mass balance analysis based on laboratory incubations demonstrated that plant residues, which retained substantial amounts of liquid (173% of dry weight on average), enabled negligible nitrogen losses, even under high ammonium loading conditions. Temporal monitoring of inorganic nitrogen forms indicated an initial phase of microbial immobilization followed by gradual remineralization, but also strong nitrogen retention within the lignocellulosic matrix. Intermediate-scale composting trials confirmed the operational feasibility of the approach. Digestate-amended piles rapidly entered the thermophilic phase, reaching 58.8°C within five days, whereas control piles treated only with water remained slightly higher than ambient levels. The results suggested that co-composting of digestate with green waste improves moisture conditions, enhances decomposition of recalcitrant biomass and mitigates ammonia-related nitrogen losses. The proposed soaking-based co-composting strategy represents a promising and scalable solution for sustainable management of both digestate and urban green waste streams.

Abstract: The disposal of chlorinated hydrocarbon (CHC) waste represents a severe environmental challenge due to the high risks of generating extremely hazardous ecotoxicants, such as dioxins, furans, and phosgene, during conventional thermal treatment. Although high-temperature plasma destruction ensures environmental safety, its widespread implementation is constrained by high energy consumption and substantial capital costs. This work aims to determine the optimal thermodynamic conditions for the allothermal, high-temperature, non-catalytic steam-carbon dioxide gasification of various CHCs to achieve their comprehensive conversion into non-toxic and industrially valuable products. Thermodynamic modeling was performed using the Aspen Plus software package in a zero-dimensional approximation based on the minimization of the Gibbs free energy at atmospheric pressure. The gasifying agent (GA) was modeled as the products of the detonation of ternary methane–oxygen–steam mixtures expanded to 0.1 MPa, with an initial temperature of 2450–2850 K (pre-calculated using Cantera and SDToolbox software packages). The computational methodology was previously validated against independent literature data on the catalytic steam conversion of a hydrocarbon surrogate (n-hexadecane) and various CHCs. The operating zone boundaries were determined for every studied compound in terms of the specific feedstock consumption m (per 1 kg of GA). Within these zones, no free oxygen, soot, or hydrocarbons are detected in the gasification products. The results show that a 100% carbon conversion efficiency (CCE) is achieved under all gasification conditions. The dry syngas yield reaches up to 5.7 nm³/kg of feedstock, with a lower heating value (LHV) of up to 17 MJ/kg (the volume fraction of combustible gases reaches 99%). The cold gas efficiency (CGE) exceeds the 100% threshold (up to 138%), confirming the efficient transformation of the energy of the detonation gases into the chemical energy of the syngas. It was established that the chlorine heteroatom is bound exclusively into hydrogen chloride (HCl), while the equilibrium volume fractions of dioxins and phosgene do not exceed a threshold value of 10-6 (1 ppm). A method for complete syngas purification via HCl dissolution in the inherent condensate of the residual steam was proposed, yielding commercial-grade hydrochloric acid. For highly chlorinated CHCs (with a chlorine content above 70%), the necessity of utilizing a blended feedstock (e.g., a CHCl₃ + C₄H₈O₂ mixture) was justified to compensate for the moisture deficit and eliminate residual free oxygen. The proposed technology of detonation-driven steam – carbon dioxide gasification can serve as an efficient, environmentally safe, and economically accessible alternative to expensive plasma-chemical methods for the disposal of toxic chlorinated organic waste.

Abstract: Phytoextraction is a sustainable strategy for removing potentially valuable elements from contaminated substrates while contributing to site remediation. However, the effectiveness of repeated phytoextractive cycles remains poorly investigated. This study evaluated the phytoextractive performance of Helianthus annuus (HA) cultivated on mining soil from Complejo Minero Fabril Sierra Pintada (Argentina) containing elevated concentrations of Ni, Zn, Sr, P, and Cu over three successive three-month cultivation cycles in TRL-4 bioreactors (BRs). The scalability of process was subsequently assessed throught projection to TRL 6 using a Vegetable Depuration Module (VDM). Elemental concentrations in soil and biomass were determined by X-ray fluorescence, while bioaccumulation coefficients, translocation factors, arbuscular mycorrhizal colonization, and glomalin-related soil proteins (GRSP) were assessed. Projected bioextractive potential in the TRL6 (VDM) during the first cycle reached 3.16 g Cu, 10.82 g Zn, 1.13 g Ni, 13.36 g Sr, and 136.91 g P. Phytoextractive efficiency declined markedly after the first cultivation cycle, indicat-ing that a single crop harvested at the flowering stage maximized element removal under the tested conditions. The accumulation of economically relevant elements in sunflower biomass could be integrated with downstream metal recovery processes, supporting the potential of HA for phytomining applications.

Abstract: Municipal solid waste (MSW) management is a critical challenge to advancing recycling and circular economic approaches. This review provides a comprehensive overview of MSW management, encompassing sourcing, policy frameworks, characterization techniques, separation technologies, preprocessing strategies, and utilization pathways. First, generation patterns and sourcing mechanisms are discussed in both U.S. and global contexts, with emphasis on the influence of policy frameworks on waste reduction and diversion. Second, characterization techniques are evaluated, focusing on physical and chemical analysis for material recyclability. Third, sorting technologies are critically re-viewed, covering conventional methods and emerging sensor-based approaches. Pre-processing techniques are then evaluated for their role in improving downstream con-version efficiency. Finally, valorization pathways such as waste-to-syngas, waste-to-biochar, and waste-to-sustainable aviation fuel (SAF) are assessed in terms of their role in climate mitigation and the circular economy. It is anticipated that this re-view provides a foundational reference for researchers, policymakers, and industry stakeholders aiming to strengthen the recyclability infrastructure and maximize the efficiency of MSW management systems in the framework of the circular economy.

Abstract: To mitigate compression heat loss during the operation of compressed air energy storage(CAES) power stations, this study proposed a design that coupled a CAES system with a heat pump system for high-temperature steam production. Focusing on waste heat utilization in a 100 MW CAES system, a tiered compression heat utilization strategy was adopted: part of the compression heat serves as a reheating source for the energy storage system’s expansion stage, while the remainder acts as a low-grade heat source for the heat pump steam generation system. This approach effectively enhances the comprehensive energy utilization efficiency of the system. Research findings demonstrated that the novel waste heat utilization system integrating a modified CAES system with a heat pump can convert 11.64 MW of secondary low-grade compressed heat into high-temperature steam. Under specific feedwater parameters(eg.,flow rate, pressure, and temperature), the system generated steam with matched operating conditions, while the heat pump subsystem achieves a Coefficient of Performance(COP) of 1.55. Analysis of variable operating conditions revealed that when the heat load of the flash-high/low-temperature regenerators remained constant, both the steam flow rate and flash rate increased with rising feedwater temperature and decreased with increasing feedwater flow rate. Furthermore, higher the feedwater flow rates combined with the lower feedwater temperature yield higher the steam temperature, peaking at 314.02 °C under optimal operating parameters; Environmental analysis indicated that the system produced substantial high-temperature steam during annual operation, achieving significant reductions in multiple pollutants emissions compared to coal-fired industrial boilers and thus providing a valuable technical reference for relevant fields.