Sewage-based biogas purification system commissioned in Japan

In Japan, Asahi Kasei and Kurashiki City held a grand opening ceremony on February 4, 2025, for a biogas purification system in Kurashiki, Okayama Prefecture, Japan. The system uses Asahi Kasei’s CO2 separation/recovery technology utilizing zeolites installed at a sewage treatment plant. The goal of this collaboration is to evaluate and demonstrate the performance of the system.

The system separates CO2 and methane from biogas using the optimum combination of a special zeolite as adsorbent that selectively adsorbs CO2 and a special pressure vacuum swing adsorption (PVSA) process technology. The zeolite is a crystalline aluminosilicate having regular channels (pores) controlled on the order of angstroms (ten-millionths of a millimeter) and cavities (voids) with a specific surface area exceeding several hundred square meters per gram. Asahi Kasei’s PVSA process technology, which separates specific gases by changes in pressure, enables the removal of CO2 from biogas to refine high-purity methane gas (biomethane) at a high recovery rate.