Development of a Pilot-scale Two-stage Anaerobic Digestion System for Manure-to-biogas Conversion

Growing environmental challenges and the transition toward sustainable energy have intensified research into biogas production from renewable substrates such as liquid manure. Conventional single-stage continuous stirred tank reactors (CSTRs) often exhibit high specific costs and limited efficiency when processing this water-rich feedstock. This study aims to develop and evaluate a pilot-scale two-stage anaerobic digestion system combining a CSTR and a packed-bed reactor. The configuration separates solid and liquid residence times, reducing hydraulic retention while improving methane yield per reactor volume. Laboratory-scale tests demonstrated up to a 75% increase in specific methane yield compared with a conventional single-stage system, confirming the potential of the two-stage design. The pilot-scale implementation seeks to validate these results under practical conditions, offering a highly automated and transferable technology for small-scale farms, thereby improving both economic and environmental sustainability in manure-based biogas production.