The Impact of Hydraulic Retention Time on the Biomethane Production from Palm Oil Mill Effluent (POME) in Two- Stage Anaerobic Fluidized Bed Reactor. - Ramadhani, Laily Isna; Damayanti, Sri Ismiyati; Sudibyo, Hanifrahmawan; Azis, Muhammad Mufti; Budhijanto, Wiratni (International Journal of Renewable Energy Development, 2021)