1. Shandong Industrial Engineering Laboratory of Biogas Production & Utilization, Qingdao, PR China
2. Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong Province, PR China
3. University of Chinese Academy of Sciences, Department of energy, Beijing, PR China
4. Dalian National Laboratory, Department of clean energy, Dalian, PR China