Waste elastomer streams are difficult to convert into high-value products because crosslinked rubber phases, service-induced chain degradation, heterogeneous interfaces, and mixed additives reduce melt reprocessability and make secondary processing unstable. In this study, a waste-derived elastomer composite was developed as a flexible, sealable, and energy-absorbing airbag layer for work-at-height fall-protection clothing. Waste thermoplastic polyurethane/polyurethane elastomer scraps were used as the main recycled matrix, while ground waste rubber was introduced as a secondary modifier to improve cushioning performance and increase waste utilization. The recycled elastomers were sorted, cleaned, regenerated, compounded with compatibilizing and modifying agents, and processed into composite airbag-layer films. A virgin TPU film was used as the control, and formulations containing different recycled elastomer contents were evaluated in terms of morphology, thermal stability, processability, mechanical integrity, airtightness, burst resistance, impact cushioning, elastic recovery, cyclic compression stability, and ageing resistance. The results showed that moderate recycled elastomer incorporation improved energy dissipation while maintaining acceptable film continuity and sealing performance. Among the tested formulations, R30, containing approximately 30% recycled elastomer, provided the best balance between functional performance and resource recovery. Compared with virgin TPU, R30 retained suitable tensile strength, elongation, seam stability, and pressure retention, while reducing peak impact force and increasing absorbed energy. Higher recycled contents increased waste diversion but caused larger dispersed domains, higher void content, weaker heat-sealed interfaces, and reduced airtightness and durability. These findings demonstrate that waste elastomers can be upcycled into functional inflatable cushioning layers when recycled content and interfacial compatibility are properly controlled. The proposed strategy provides a potential high-value recycling pathway for flexible polymer waste in wearable protective equipment.
Biodegradable waste constitutes over 50.8% of solid waste streams in Tarlac Agricultural University. This study evaluated the performance and biochar yields of a closed-fired, low-cost drum type carbonizer for mahogany and bamboo residues. The whole system includes a central vertical heat conduit pipe. The furnace has a based enclosure for firing, a firing bed and an ash tray. The carbonizer was fabricated from locally available materials for only 47.13 USD and operated for 3-hour batches using seasoned firewood (25-30 kg Batch −1 ; 15.5 MJ kg −1 energy input) also available in the university. The performance of the system was evaluated by operating on 3-hour batch cycles using seasoned firewood. Performance evaluation using a single-factor completely randomized design revealed a biochar recovery yield of 39.33% from bamboo, 36.00% from mahogany shells, and 26.00% from mahogany leaves. The carbonizer operated with highly consistent thermal dynamics across all treatments, showing no significant differences in its specific energy requirement of 0.545 MJ/kg, fuel consumption rate of 8.56 kg/hr, total energy consumed of 502 MJ, and operating time of 3.3 hours. Proximate analysis revealed volatile combustible matter ranging from 66.60% to 93.07%, ash content from 3.40% to 19.80%, and fixed carbon from 3.53% to 13.60%. Higher heating values of 17.09 to 18.43 MJ/kg combined with atomic H/C ratios of 1.49-1.60 indicating a low-temperature slow pyrolysis process of 350-450°C. Bamboo biochar is recommended for soil conditioning, mahogany shell biochar for composting additives, and mahogany leaf biochar as supplemental fuel. This simple design provides a technically feasible, decentralized baseline for green-campus waste management.
FRP formwork containing recycled construction waste may reduce material consumption, but recycled particles can introduce interfacial defects, weaken interlaminar load transfer, and accelerate stiffness loss under humid-heat exposure, eccentric loading, and variable boundary constraints. This study clarifies the degradation mechanism and develops an optimization design method for recycled-particle-modified FRP formwork. A coupled framework was established by linking recycled aggregate replacement ratio, particle size, water absorption, fiber volume fraction, number of plies, formwork thickness, adhesive-layer thickness, humid-heat cycles, eccentricity, distributed pressure, and boundary stiffness. Orthogonal experiments with 162 valid specimens were used to identify degradation states, calibrate damage evolution parameters, and validate a constraint-driven multi-objective optimization algorithm. The results show that increasing the recycled aggregate replacement ratio and humid-heat cycles jointly reduced elastic modulus retention, interlaminar shear resistance, and bending stiffness. When the replacement ratio exceeded 20% and humid-heat cycles exceeded 200, elastic modulus retention dropped below 0.65, indicating a critical transition in interfacial damage accumulation. After optimization, the replacement ratio was adjusted from 20% to 15.2%, the fiber volume fraction increased from 50% to 56.8%, and the ply number increased from 6 to 8. The optimized formwork achieved a 19.6% increase in bending stiffness, a 13.6% reduction in structural mass, a 16.7% reduction in interfacial shear stress, and a 20.5% reduction in maximum deflection. The main innovation lies in connecting recycled-particle-induced interface degradation with constrained structural optimization, thereby shifting recycled FRP formwork design from material feasibility assessment to service-reliability-oriented parameter control.
Waste-to-fuel (WtF) technologies are increasingly positioned as enablers of a low-carbon circular economy because they simultaneously address two structural challenges: rising residual-waste volumes and the demand for dispatchable low-carbon energy carriers. Their contribution, however, hinges not on nominal energy recovery but on feedstock quality, conversion stability, lifecycle emissions, policy alignment and exposure to price-, supply- and infrastructure-related risks. This article presents a mixed-methods comparative evaluation of six pathways—anaerobic digestion, pyrolysis, gasification, waste-oil biodiesel, refuse-derived fuel (RDF) and hydrothermal liquefaction (HTL). The six were retained after an explicit four-family taxonomy screen (thermochemical, biochemical, chemical, electrochemical), with electrochemical routes (e.g., microbial fuel cells) excluded due to sub-pilot commercial maturity and orders-of-magnitude lower volumetric energy yields. Drawing on 78 peer-reviewed sources (2021–2026) plus UN, IEA, IRENA, OECD and World Bank reports, the study triangulates techno-economic reasoning, lifecycle synthesis and a six-factor energy-risk index (technical, economic, supply, environmental, policy, infrastructure). The novelty lies in jointly ranking pathways by efficiency, carbon intensity and risk while integrating social-acceptance evidence often missing from review work. Findings indicate that no single pathway is universally optimal: anaerobic digestion and waste-oil biodiesel are the most mature and lowest-risk; gasification and pyrolysis are most flexible and high-value but carry elevated technical and market risk; HTL is promising for wet residuals but capital-intensive; and RDF is best confined to non-recyclable combustibles in cement kilns. A defensible transition therefore demands technology–feedstock matching, risk-weighted deployment, improved source segregation and transparent carbon accounting, rather than blanket technology promotion.
The discharge of dye-containing wastewater poses a serious environmental challenge due to its toxicity, persistence, and resistance to conventional treatment methods. Photocatalysis has emerged as a sustainable and effective approach for the degradation of such organic pollutants, with ZnO- and Ag 3 PO 4 -based semiconductors widely studied for their favorable optical properties. However, their practical application is limited by poor visible-light utilization and rapid electron–hole recombination. In addition, while binary composites have been extensively investigated, ternary systems such as AgBr/Ag 3 PO 4 /ZnO and their synergistic effects remain insufficiently explored. Therefore, the objective this study or this study aims to develop efficient visiblelight-driven ZnO-based photocatalysts and to evaluate the influence of composite formation on their structural, optical, and photocatalytic performance such as in environmental remediation through dye purifications. ZnO and Ag 3 PO 4 nanoparticles, along with Ag 3 PO 4 /ZnO and AgBr/Ag 3 PO 4 /ZnO nanocomposites, were synthesized via a direct precipitation method and characterized using XRD, SEM, AAS, and UV–Vis spectroscopy. Photocatalytic activity was assessed through the degradation of crystal violet under visible-light irradiation. The AgBr/Ag 3 PO 4 /ZnO nanocomposite exhibited the highest photocatalytic efficiency, attributed to reduced band gap energy and improved charge separation resulting from synergistic interactions. These findings highlight the potential of ternary composite design for enhanced visible-light-driven photocatalysis in wastewater treatment applications.
