Metallic nanoparticles for enhanced biogas production from conventional and lignocellulosic substrates

This review explores the application of metallic nanoparticles (MNPs) to enhance biogas production through anaerobic digestion (AD), from conventional and lignocellulosic substrates. MNPs have proven to increase methane yields, improve biogas quality, and accelerate microbial activity. However, the effectiveness of MNPs depends on factors such as dosage, type, and capping/functionalization. To address the challenges of digesting lignocellulosic biomass, strategies such as combining MNPs with traditional pretreatments, functionalizing nanoparticles (NPs) with acids, or immobilizing ligninolytic enzymes on magnetic NPs are discussed. These strategies improve hydrolysis and enhance methane production from recalcitrant substrates. Also, this review highlights sustainable techniques for MNPs application, including green synthesis of NPs using plant or microorganism extracts, recycling NPs and reusing digestates as biofertilizers.