A method for methane separation and purification from a biogas, comprising the steps of: collecting a raw Biogas stream, the raw Biogas stream including at least methane, carbon dioxide, water, hydrogen sulfide, and non-methane organic compounds (NMOC); performing a raw Biogas stream separation procedure in which the raw Biogas stream is separated into a sulfur compounds stream and a main gas stream, the sulfur compounds stream being removed from further processing, the main gas stream being purified from the hydrogen sulfide; processing the main gas stream by means for adsorbing the NMOC, wherein the recovered NMOC is liquefied, the NMOC liquid stream being removed from further processing, the main gas stream being substantially purified from the non-methane organic compounds; performing a main gas stream separation procedure in which the main gas stream is separated into an off-gas stream substantially composed of carbon dioxide, nitrogen, and oxygen gas, and a product stream composed substantially of purified methane gas; performing an off-gas stream adsorbing procedure, thereby forming a vent gas stream and a recycle stream, wherein the recycle stream is depleted in carbon dioxide, oxygen, nitrogen, but is enriched in methane and NMOC relative to the off-gas stream; venting the vent gas stream into the atmosphere; and mixing the recycle stream with the main gas stream after the step of performing a raw Biogas stream separation procedure and before the step of adsorbing non-methane organic compounds, wherein said step of performing an off-gas stream adsorbing procedure further comprises the step of forcing said off-gas stream to come in contact with nanoporous and or microporous adsorbent materials selective for methane and non-methane organic compounds (NMOC) and nonselective for carbon dioxide, oxygen, and nitrogen, wherein said raw Biogas stream separation procedure further comprises the step of using a solid adsorption material to capture the hydrogen sulfide (H 2 S) for removal from the raw Biogas stream, and wherein said step of adsorbing non-methane organic compounds (NMOC) further comprises the step of using adhesion of molecules of the NMOCs to surfaces and pores of selective adsorbent materials. collecting a raw Biogas stream, the raw Biogas stream including at least methane, carbon dioxide, water, hydrogen sulfide, and non-methane organic compounds (NMOC); performing a raw Biogas stream separation procedure in which the raw Biogas stream is separated into a sulfur compounds stream and a main gas stream, the sulfur compounds stream being removed from further processing, the main gas stream being purified from the hydrogen sulfide; processing the main gas stream by means for adsorbing the NMOC, wherein the recovered NMOC is liquefied, the NMOC liquid stream being removed from further processing, the main gas stream being substantially purified from the non-methane organic compounds; performing a main gas stream separation procedure in which the main gas stream is separated into an off-gas stream substantially composed of carbon dioxide, nitrogen, and oxygen gas, and a product stream composed substantially of purified methane gas; performing an off-gas stream adsorbing procedure, thereby forming a vent gas stream and a recycle stream, wherein the recycle stream is depleted in carbon dioxide, oxygen, nitrogen, but is enriched in methane and NMOC relative to the off-gas stream; venting the vent gas stream into the atmosphere; and mixing the recycle stream with the main gas stream after the step of performing a raw Biogas stream separation procedure and before the step of adsorbing non-methane organic compounds, wherein said step of performing an off-gas stream adsorbing procedure further comprises the step of forcing said off-gas stream to come in contact with nanoporous and or microporous adsorbent materials selective for methane and non-methane organic compounds (NMOC) and nonselective for carbon dioxide, oxygen, and nitrogen, wherein said raw Biogas stream separation procedure further comprises the step of using a solid adsorption material to capture the hydrogen sulfide (H 2 S) for removal from the raw Biogas stream, and wherein said step of adsorbing non-methane organic compounds (NMOC) further comprises the step of using adhesion of molecules of the NMOCs to surfaces and pores of selective adsorbent materials.