System and method to recycle the water and ammonia and optionally other cell media nutrients for a power-to-gas plant in biological methanation utilizing biocatalyst (methanogen)

A biomethanation method in a bioreactor utilizing a culture of methanogenic microorganisms in a culture medium for producing and collecting methane or a methane enriched gas composition comprising the steps of:

• i. recycling of at least one ammonia compound and/or;
• ii. recycling of electrons;
• wherein water (H2O) serves as the carrier for electrons;
• including the steps of:
• a. culturing in the bioreactor the methanogenic microorganisms in a suitable liquid culture medium comprising minerals in a continuous process;
• b. extracting from the culture medium a metabolic water fraction comprising an at least one ammonia compound and the electron carrier water;
• c. separating the at least one ammonia compound and/or the water of the metabolic water fraction;
• d. isolating the separated at least one ammonia compound and/or the water, wherein the water is in the form of pure water;
• and
• e. redosing at least one fraction of the isolated at least one ammonia compound into the bioreactor and/or recycling the pure water to an electrolyzer,
• wherein the recycling of electrons further comprises:
• performing a reductive power regeneration with the isolated pure water by electrolysing the pure water and recycling the regenerated electrons back in the bioreactor, wherein H2 serves as an intermediate electron carrier.