Membrane photobioreactor for biogas capture and conversion – Enhanced microbial interaction in biofilm

The urgency to mitigate greenhouse gas emissions has driven interest in sustainable biogas utilization. This study investigates a 1 L enclosed membrane photobioreactor (MPBR) using a microalgae-methanotroph coculture for biogas capture. Operating with a hydraulic and solid retention time of 7 days and a biogas loading rate of 2.7 L /day, the introduction of gas membrane module increased CO₂-C and CH₄-C uptake rates by 12 % and 50 %, respectively. Biofilm formation on the membrane surface enhanced system performance, with imaging analyses revealing methanotroph predominantly located near the membrane surface and photosynthetic microorganisms distributed throughout. Metagenomic analysis showed shifts in key metabolic pathways, including increased abundance of soluble methane monooxygenase genes and enhanced vitamin B synthesis in the biofilm. These findings highlight the spatial organization and metabolic interactions in methanotroph-microalgae coculture system, providing insights into the role of membrane-induced biofilms in improving MPBR performance for sustainable biogas utilization.