Caulerpa lentillifera residue is a high-ash macroalgal waste with potential for solid biofuel production, but its direct utilization is limited by high volatile matter and inorganic content, which may cause flame instability, slagging, and fouling during combustion. This study investigated the atmosphere-dependent torrefaction of C. lentillifera residue under N 2 , air, and CO 2 atmospheres and optimized the process using response surface methodology over a temperature range of 250–300 °C and a residence time of 15–45 min. The optimization framework considered fuel-ratio improvement, ash-related constraints, deoxygenation, heating value, and energy retention. The results revealed clear trade-offs among fuel upgrading, ash enrichment, and energy retention depending on the reaction atmosphere. Air torrefaction gave the fastest fuel-quality improvement, reaching the optimized condition at 279 °C in only 15 min with the highest fuel ratio, but at the cost of stronger ash enrichment and a validated energy–mass co-benefit index (EMCI) of 14.32%, below the 15% target adopted in this work. N 2 torrefaction retained the highest EMCI (25.80%), and CO 2 behaved similarly to N 2 (17.82%). Rather than a single best atmosphere, the results define three operating routes: N 2 for energy retention, air for rapid throughput, and CO 2 as a potential route relevant to flue-gas integration. Overall, the findings demonstrate that atmosphere selection is critical for defining practical operating windows for macroalgal residue torrefaction, where rapid fuel upgrading must be balanced against ash enrichment and energy-retention losses.
Post-harvest rubber seeds (Hevea brasiliensis) accumulate across Indonesian plantations as cyanogenic residues that remain commercially unrecovered, resulting in both resource underutilization and disposal burdens. This study couples agricultural residue valorization with coal upgrading by converting rubber seed oil into methyl ester sulfonate (MES), a bio-based anionic surfactant, and applying hydrothermal dewatering to sub-bituminous coal at 200 and 250 °C to reduce inherent moisture and oxygenated surface functionalities. Interfacial tension measurement indicated an effective critical micelle concentration (CMC) of 2.5 g/L for MES against 15.0 g/L for commercial sodium lignosulfonate (SL), with MES reducing interfacial tension by 99.4% versus 29.1% for SL. Both were evaluated as dispersants for coal-water slurry (CWS) at 55 wt% solids loading. Rheological measurements showed that MES satisfied the <1000 mPa s slurry-feed gasifier specification at 2.5 g/L, roughly 2.8-fold lower than the interpolated effective SL dosage, reducing chemical mass input per unit of processed fuel. Zeta potential analysis confirmed stronger electrostatic stabilization by MES, reaching −74.4 mV at 10 g/L for hydrothermally upgraded coal and exceeding the excellent-stability threshold (|ζ| > 60 mV). Static stability tests demonstrated penetration ratios above 80% after 2 h. MES also showed a fivefold lower S/C ratio and roughly half the ash content of SL (14.2 vs 25.2 wt% at 900 °C), reducing the dispersant-derived sulfur and inorganic input to gasification. This integrated approach delivers three cleaner-production outcomes: valorization of an unmanaged agricultural residue, enhanced slurry rheology and stability at lower dispersant dosage, and reduced inorganic loading in coal gasification feed.
Agri-food supply chains play a critical role in sustainable development but continue to face challenges related to resource-intensive production, food loss, and environmental impacts. The Bio-Circular-Green (BCG) economy offers an integrated pathway toward sustainability through bio-based resource utilization, circular material flows, and environmentally responsible operations. This study proposes an integrated Circular Intuitionistic Fuzzy Multi-Criteria Decision-Making (CIF-MCDM) framework with Quality Function Deployment (QFD) to prioritize sustainable supply-chain capabilities (SSCCs) supporting BCG implementation in agri-food systems. Grounded in the Resource-Based View (RBV) and Dynamic Capabilities View (DCV), the framework incorporates stakeholder priorities, capability interdependencies, and uncertainty in expert judgments within a unified decision-support structure. An end-to-end rice supply chain under Thailand's Royal Patronage BCG pilot project is employed as the case study. The methodological contribution lies in integrating CIF theory with deployment-oriented capability analysis to simultaneously evaluate stakeholder requirements, causal interrelationships, and strategic capability priorities under uncertainty. The results identify bio-quality and food safety compliance, traceability, and waste reduction as the most critical stakeholder requirements for BCG implementation. After incorporating network interdependencies, the top three prioritized SSCCs are closed-loop coordination and stakeholder engagement, circular reuse, recycling, and responsible disposal, and reverse logistics and recovery management. The findings demonstrate that circular and return-oriented capabilities exert the strongest systemic influence on BCG supply-chain performance. From a managerial perspective, organizations should prioritize integrated circular coordination mechanisms and reverse logistics infrastructures before pursuing advanced sustainability initiatives to strengthen long-term sustainability, resilience, and circularity performance.
