Biogas purification unit uses anaerobic digestion technology, which is mainly used to treat livestock manure and high concentration industrial organic wastewater. After decades of R & D and application, many large and medium-sized biogas projects have been built in China. Both the accumulation of anaerobic digestion technology and the experience in construction, operation and management are among the international advanced ranks. It also lays a foundation for the application of biogas power generation technology.