Dose-Dependent Effects of Coconut Shell Biochar on Biogas Yield and Inhibitor Reduction in Dairy Manure Anaerobic Digestion Systems

Abstrak

This study evaluated the effect of coconut shell biochar on dairy manure anaerobic digestion using 1000 mL reactors at 35 ± 1°C. Fresh dairy manure (TS: 18.2 ± 0.5%, VS: 14.7 ± 0.3%, C/N: 25:1) from Kendari, Indonesia, was amended with biochar (surface area: 480–520 m²/g) at 5%, 10%, and 15% (w/w of TS) in triplicate. Biochar was produced via slow pyrolysis (500°C, 2 h, N₂ atmosphere). Biogas yield and pH were monitored using wet-tip gas meters and a Hanna HI98107 pH meter. The 10% biochar dose yielded 0.28 L CH₄/g VS, a 32% increase over the control, by reducing ammonia (40%), stabilizing volatile fatty acids, and promoting microbial colonization (SEM-confirmed). Biochar maintained pH at 7.2–7.7 and shortened the lag phase by two days (Gompertz model). The 15% dose was less effective due to reduced substrate-microbe interactions. This validates 10% biochar as a cost-effective amendment for farm-scale biogas systems.

Kata kunci

• Anaerobic digestion
• Biochar
• Circular Economy
• Dairy Manure
• Microbe