Effect of harvesting interval on biogas production from Napier grass

Abstract

Biomethane (CH₄) is a renewable energy source that can be generated from organic waste through environmentally sustainable methods utilising anaerobic digestion (AD) technology. This study uses the automatic methane potential test system (AMPTS-III) to examine the biogas potential of Napier grass (NG, Pennisetum purpureum) harvested at various growth stages (1, 2 and 3 months). The range of NG Total solids (TS) and Volatile solids (VS) during the various harvest periods was 0.9406 to 0.9540 g g⁻¹ of substrate/inoculum and 0.9235 to 0.9848 g g⁻¹ of TS, respectively. Profiles of biogas production revealed that the 2-month-old NG achieved the highest cumulative volume up to 3083.20±160.30 NmL. The biomethane potential (BMP) of NG were 204.30±25.26 NmL g⁻¹ VS, 412.70±45.94 N mL g⁻¹ VS and 354.43±31.25 NmL g⁻¹ VS for 1, 2, 3-month period, respectively. The timing of the harvest significantly influenced CH₄ yield, with the 2-month harvest exhibiting the highest levels of digestibility and organic content. The 2-month-old NG demonstrated a 50.49% increase in BMP as compared to the 1-month samples and a 14.11% increase over the 3-month samples, highlighting the importance of harvest timing in optimising energy recovery for sustainable biogas production.

Keywords

Biomass / Biogas / AMPTS-III study / Anaerobic digestion / Agriculture waste

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