Removal of Ammonia from Biogas

Ammonia is a nitrogen compound frequently generated during the anaerobic digestion of nitrogen-rich organic substrates used for biogas production. It originates primarily from the degradation of proteins, amino acids, and other nitrogen-containing compounds present in agricultural residues, municipal wastewater, sludge, and agroindustrial effluents. While moderate concentrations of ammonium contribute to buffering capacity and microbial nutrition within anaerobic digesters, excessive accumulation can inhibit methanogenic archaea, disrupt microbial syntrophic interactions, and reduce methane production efficiency. Consequently, ammonia represents both a biochemical challenge for anaerobic digestion stability and an operational concern for biogas purification systems. In addition to its inhibitory effects on microbial communities, ammonia may also affect downstream biogas upgrading processes by contributing to corrosion, catalyst deactivation, and fouling of purification units. Understanding the origin, transformation, and behavior of ammonia in anaerobic systems is therefore essential for optimizing reactor performance and ensuring high-quality biomethane production. This chapter provides a comprehensive overview of ammonia formation pathways in anaerobic digestion and its implications for biogas production and upgrading. The main nitrogen sources in waste streams commonly integrated into biogas systems are examined, along with the microbial processes governing ammonia release. Furthermore, the chapter reviews current and emerging technologies for ammonia removal and recovery, including physicochemical, biological, membrane-based, and electrochemical approaches. Integrating these strategies can improve process stability, enhance biomethane quality, and support nutrient recovery within circular bioeconomy frameworks.