Membrane Absorption of Ammonia from Anaerobic Digester Biogas Using Sulfuric Acid Stripping Solution

Abstract

Ammonia present in anaerobic digester biogas contributes to equipment corrosion, catalyst poisoning, odor generation, and reduced biogas quality, necessitating effective ammonia removal technologies for sustainable biogas utilization. The present study investigates the membrane absorption of ammonia from anaerobic digester biogas using sulfuric acid as a stripping solution under controlled operational conditions. The research focuses on evaluating ammonia transfer efficiency, membrane performance, mass transfer behavior, and process optimization associated with membrane absorption systems. Experimental analysis was conducted to examine the influence of gas flow rate, sulfuric acid concentration, membrane characteristics, temperature, contact time, and ammonia concentration on removal efficiency and operational stability. Results demonstrate that membrane absorption effectively promotes selective ammonia transfer across the membrane interface through concentration gradient-driven mass transfer mechanisms, resulting in substantial reduction of ammonia content in treated biogas. The study further reveals that optimized sulfuric acid concentration and operating conditions significantly enhance ammonia capture efficiency while maintaining stable membrane performance and minimizing mass transfer resistance. Increased gas–liquid contact conditions contributed to improved ammonia absorption and formation of ammonium sulfate as a valuable byproduct suitable for fertilizer applications. Comparative assessment with conventional ammonia removal technologies confirms the advantages of membrane absorption systems, including lower energy consumption, compact system configuration, and reduced chemical losses.