An Advanced Biogas Plant for Bio-Circular Economy from Pig Manure in Taiwan Tsung-Hsien Chen1,3, Chen-Yeon Chu1,2,3* 1 Ph. D. Program of Mechanical and Aeronautical Engineering, Feng Chia University, Taichung, Taiwan 2 Master's Program of Green Energy Science and Technology, Feng Chia University, Taichung, Taiwan