T he objective of this study was to investigate the chlorine-related challenges in Automotive Shredder Residue (ASR) by developing a de-chlorination strategy and formulating Solid Recovered Fuel (SRF) pellets with improved environmental and fuel quality. A ternary blending approach was employed using Fe–Ca-based inorganic dechlorinating agents and thorny bamboo biomass as co-materials with ASR. The de-chlorination efficiency, calorific value, and ash content of the resulting SRF were evaluated. Results indicated that the optimal dechlorinating formulation reduced the chlorine content of PVC from 43.26 wt% to 0.59 wt%, achieving a de-chlorination efficiency of 97.23%. A second-order polynomial regression model （ η_DeCl = –1.5277x² + 2.5519x – 0.0225 ， R² = 0.9347 ） was developed to predict the de-chlorination performance based on the blending ratio of dechlorinating agent to ASR, demonstrating behavior consistent with first-order reaction kinetics observed in pyrolytic de-chlorination. The final ternary formulation—comprising 55% thorny bamboo, 37.5% ASR, and 7.5% dechlorinating agent—produced SRF pellets with improved overall quality, demonstrating effective chlorine control, reasonable ash content, and enhanced thermal properties suitable for regulatory compliance and practical application. S uch findings meet the criteria set by EN ISO 21640:2021 (Class 2), JIS Z7311 (Grade A), and forthcoming Taiwanese SRF regulations. B ased on the findings in this work it can be stated that the high de-chlorination potential of Fe–Ca-based additives for chlorine-rich waste and introduces a predictive formulation model that supports both resource circularity and clean fuel production.

Mycorrhizae are symbiotic associations between the roots of vascular plants and fungi that facilitate the uptake of water and nutrients by host plants. However, current arbuscular mycorrhizal fungi (AMF) cultivation methods including sand culture, root organ culture, and aeroponics are complex and time-consuming. Moreover, these methods produce low spore yields hindering large-scale production and sustainable application of MF in agriculture. This study systematically evaluated the effects of biochar amendment on the propagation of AMF spores in sandy soils, focusing on how different biochar application rates influence AMF spore density and related soil physicochemical properties. The results showed that increasing biochar concentration led to higher soil pH and EC, suggesting enhanced microbial activity and dynamic adjustments in soil chemical conditions. A typical biphasic response was observed. At low biochar concentrations (approximately 1–1.8%), soil porosity, organic carbon content, and trace element availability were improved, thereby promoting AMF spore formation and hyphal growth. However, concentrations exceeding 2.5% induced physicochemical stress that inhibited fungal propagation. Polynomial regression analysis (R² = 0.996) confirmed a strong correlation between biochar concentration and AMF spore density, clearly capturing a promotion–plateau–inhibition pattern. In addition, SEM imaging revealed that AMF hyphae adhered to the porous surface of biochar, forming stable hyphal networks that enhance nutrient transport and contribute to rhizosphere microenvironmental stability.

Increasing fertilizer costs, climate-related stresses, and soil degradation caused by the prolonged use of chemical fertilizers threaten the sustainability of agricultural production. Organic soil amendments offer a promising approach to restoring soil health while reducing dependence on synthetic inputs. This study evaluated the combined effects of biochar and organic fertilizer on soil health and soybean (Glycine max L.) productivity under acidic soil conditions. During the 2024 growing season, a greenhouse pot experiment was conducted using a completely randomized design (CRD) comprising seven treatments. Each treatment was replicated three times, resulting in a total of 21 pots. The treatments consisted of different combinations of biochar (B) and organic fertilizer (F), applied at rates of grams per 10.5 kg of soil: control (B0F0), B35F70, B35F105, B35F140, B70F70, B70F105, and B70F140. Treatment means were compared using the Least Significant Difference (LSD) test at p < 0.05. The results showed that the highest soil pH value (5.41) was recorded under the B35F70 treatment at 45 days after amendment of the acidic soil. Application of the B35F140 treatment resulted in a significant increase (p < 0.05) in electrical conductivity (0.23 mS cm⁻¹) compared with the control. Soil organic matter and available phosphorus reached their highest values under B70F140, at 5.25% and 13.87 mg kg⁻¹, respectively, and were significantly greater than those in the control treatment. Soil available iron (Fe) and manganese (Mn) concentrations also increased significantly (p < 0.05) compared with the control, with the B35F70 and B70F70 treatments resulting in the highest Fe (371.29 mg kg⁻¹) and Mn (37.77 mg kg⁻¹) concentrations, respectively. At 100 days after amendment of the reddish-brown acidic soil, exploratory Pearson correlation analyses were conducted to examine relationships between soil health indicators and soybean performance. Soil available phosphorus and potassium exhibited positive associations with soil pH (r = 0.69 and r = 0.65, respectively; p < 0.01). Soybean growth traits, including plant height and number of leaves, were positively associated with seed yield (r = 0.56 and r = 0.77, respectively; p < 0.01). Furthermore, seed yield was positively correlated with SPAD values (r = 0.80, p < 0.01), soil pH (r = 0.56, p < 0.01), available K (r = 0.68, p < 0.01), and Mg (r = 0.47, p < 0.05). Principal component analysis (PCA) further demonstrated clear treatment clustering and consistent positive relationships among soil properties, plant growth traits, and soybean yield variables. The control treatment was clearly separated from all biochar-organic fertilizer treatments along PC1. Among all treatments, B35F140 (3.33 g biochar kg⁻¹ soil + 13.33 g organic fertilizer kg⁻¹ soil) showed the strongest positive association with soil health and plant growth and produced the highest soybean seed yield (10.77 g plant⁻¹). Overall, the combined use of biochar and organic fertilizer improved soil health, soybean growth, and yield, demonstrating its potential as a sustainable strategy for enhancing soybean productivity under acidic soil conditions.