• • Optimal VFA production at 35 °C: 344.22 mg/g COD, with peak VFA concentration of 14,267 mg/L after 5 days, significantly outperforming 55 °C (57.16 mg/g COD), indicating mesophilic fermentation is economically favorable for industrial acid production.
• • Acetic acid constitutes 95.6%–98.9% of VFAs across all temperatures, simplifying downstream purification and making the product suitable as a carbon source for biological nutrient removal.
• • Protein and carbohydrate degradation rates are highest at 35–45 °C, while lipid degradation peaks at 55 °C, suggesting temperature-specific substrate targeting for optimized co-digestion strategies.
• • Fungal community at peak acid production is dominated by cellulose-degrading genera (e.g., Oligophagozyma at 90.07% at 35 °C), with saprotrophic fungi prevailing, indicating a key role in lignocellulose breakdown.