Comparative assessment of agricultural and municipal biogas plants in terms of process stability and efficiency

Biogas is a crucial renewable energy source, as it supports a circular economy by facilitating the efficient recovery of energy from organic waste through recycling. This study presents a comparative case study assessment of one agricultural and one municipal biogas plant regarding process stability, production efficiency, and digestate quality. The analysis was conducted at two full-scale anaerobic digestion (AD) facilities operating under different technological and feedstock conditions. The agricultural biogas plant, processing mainly maize silage and agri-food residues, demonstrated slightly higher biogas yields (average 127 m 3 /ton) and methane concentrations (53.7–55.1 %) compared to the municipal biogas plant treating selectively collected biowaste (116 m 3 /ton and 50.4–52.3 %, respectively). Despite the municipal plant's higher operational complexity and purification requirements, both installations maintained stable digestion processes, confirmed by appropriate pH levels and acidity/alkalinity ratios. Digestate from both plants met the legal standards for use as a biofertilizer, though the agricultural digestate showed a higher nutrient content. The findings confirm that both agricultural and municipal full-scale AD configurations can operate as effective and stable methods for biowaste treatment and energy recovery, contributing to circular economy goals and climate neutrality. • Biogas plants can be an integral part of the waste management system. • Biogas represents the most controllable form of renewable energy. • Specific biogas yield is slightly higher in the case of agricultural biogas plant. • The obtained digestate can be used as a biofertilizer. • Biogas plants can support a circular economy by contributing to efficient recovery.