A method for recovering helium from a feed stream (S100) containing helium, carbon dioxide and at least one of methane and nitrogen, the method comprising: introducing a separator feed (S125) stream into a separator (C110), the separator feed stream (S125) comprising at least a portion of the feed stream (S100), separating the separator feed stream (S125) into a first helium-enriched stream (S106) and a first CO 2 -enriched stream (S115), and withdrawing the first helium-enriched (S106) stream and the first CO 2 -enriched stream (S115) from the separator (C110); introducing a pressure swing adsorption unit feed stream (S107) into a pressure swing adsorption unit (A100), the pressure swing adsorption unit feed stream (S107) comprising at least a portion of the first helium-enriched stream (S106), separating the pressure swing adsorption unit feed stream (S107) into a helium-rich product stream (S108) and a helium-lean stream (S109), and withdrawing the helium-rich product stream (S108) and the helium-lean stream (S109) from the pressure swing adsorption unit (A100); compressing a compressor feed stream (S205) in a compressor (K101) to form a compressor effluent stream (S110), the compressor feed stream (S205) comprising the helium-lean stream (S109) and a helium-enriched permeate stream (S203); introducing a first portion (S201) of the compressor effluent stream (S110) into a membrane separation unit (M100), separating the first portion (S201) of the compressor effluent stream (S110) to form the helium-enriched permeate stream (S203) and a helium-depleted non-permeate stream (S204), and withdrawing the helium-enriched permeate stream (S203) and the helium-depleted non-permeate stream (S204) from the membrane separation unit (M100); and introducing a second portion (S202) of the compressor effluent stream (S110) into the separator (C110). introducing a separator feed (S125) stream into a separator (C110), the separator feed stream (S125) comprising at least a portion of the feed stream (S100), separating the separator feed stream (S125) into a first helium-enriched stream (S106) and a first CO 2 -enriched stream (S115), and withdrawing the first helium-enriched (S106) stream and the first CO 2 -enriched stream (S115) from the separator (C110); introducing a pressure swing adsorption unit feed stream (S107) into a pressure swing adsorption unit (A100), the pressure swing adsorption unit feed stream (S107) comprising at least a portion of the first helium-enriched stream (S106), separating the pressure swing adsorption unit feed stream (S107) into a helium-rich product stream (S108) and a helium-lean stream (S109), and withdrawing the helium-rich product stream (S108) and the helium-lean stream (S109) from the pressure swing adsorption unit (A100); compressing a compressor feed stream (S205) in a compressor (K101) to form a compressor effluent stream (S110), the compressor feed stream (S205) comprising the helium-lean stream (S109) and a helium-enriched permeate stream (S203); introducing a first portion (S201) of the compressor effluent stream (S110) into a membrane separation unit (M100), separating the first portion (S201) of the compressor effluent stream (S110) to form the helium-enriched permeate stream (S203) and a helium-depleted non-permeate stream (S204), and withdrawing the helium-enriched permeate stream (S203) and the helium-depleted non-permeate stream (S204) from the membrane separation unit (M100); and introducing a second portion (S202) of the compressor effluent stream (S110) into the separator (C110). <EOS>