Methods of anaerobic digestion of biomass to produce biogas

A method of producing biogas comprising:

• (a)(i) transferring an organic substrate to a hydrolysis tank;
• (a)(ii) hydrolyzing the substrate in anaerobic conditions in the hydrolysis tank to produce a hydrolysis liquid effluent;
• (b)(i) transferring the hydrolysis liquid effluent for a period of time 1 to a methanogenesis tank 1 comprising fixed film methanogens or granular methanogens and producing biogas and methanogenesis tank 1 liquid effluent;
• (b)(ii) transferring the methanogenesis tank 1 liquid effluent to a methanogenesis tank 2 comprising fixed film methanogens or granular methanogens during period of time 1 and producing biogas and methanogenesis tank 2 liquid effluent in methanogenesis tank 2;
• (b)(iii) discharging methanogenesis tank 2 liquid effluent during period of time 1;
• and then switching the order of methanogenesis tanks 1 and 2 and
• (c)(i) transferring the liquid hydrolysis effluent for a period of time 2 to said methanogenesis tank 2 and producing biogas and methanogenesis tank 2 liquid effluent in methanogenesis tank 2;
• (c)(ii) transferring the methanogenesis tank 2 liquid effluent to said methanogenesis tank 1 during period of time 2 and producing biogas and methanogenesis tank 1 liquid effluent in methanogenesis tank 1;
• (c)(iii) discharging methanogenesis tank 1 liquid effluent during period of time 2.