TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Composition: The gas (G2) comprises nitrogen, hydrogen or methane.The gas stream comprises an effluent stream from petrochemical manufacturing process, refinery process or from polyolefin manufacturing process, and natural gas.The organic component comprises C3+ hydrocarbon or olefin.The membranes comprise a silicone rubber selective layer.Preferred Conditions: The membrane separation step (111) operated at pressure ratio (phi), and selectivity (alpha) for the organic component over gas (G2), satisfy a relation:alpha/phi at most 5.The separation step (111) operated at pressure ratio phi, and the remaining stream containing olefin in concentration (C%), satisfy a relation: 100/C at most 5phi.The pressure is lowered in withdrawn stream to form light gas stream and liquid petroleum gas (LPG) stream, or light gas stream and natural gas liquid stream. EXAMPLE - Off-gas stream from polyethylene manufacturing purge bin comprising hydrogen (in mol%) (1), nitrogen (15.1), C2 (7.5), C3 (0.1), butanes (75.7), C5+ (0.3) and water (0.1), was mixed with the return stream (R1) to form a steam which was introduced into the compression stage (C1) and gas pressure was raised to 65 psi. The compressed gas was mixed to another return stream (R2) to form stream which was introduced to compression stage (C2) and gas pressure was raised to 288 psi. The compressed stream was cooled and separated to form butane-rich organic condensate stream and nitrogen-enriched non-condensed stream. The organic condensate stream was reduced in pressure and passed into flash tank. The light overheated gas, returned stream (R2) was flashed off to form stream rich in ethylene and nitrogen, which was recirculated to compression stage (C2). The final condensate stream was removed from flash tank bottom. The non-condensed stream passed into membrane separation step (S1) and separated into nitrogen-enriched residue stream (RS1) and organic-enriched permeate stream. The permeate stream was recirculated to compressor intake of compression stage (C2). The residue stream was passed to membrane separation step (S2) where it was separated into residue stream (RS2) and permeate stream which was recirculated into compression stage (C1). The residue stream RS2 was passed to membrane separation sub-step (S2) where it was separated into residue stream (RS3) having nitrogen-rich product stream and permeate stream. The obtained permeate stream was split into stream which was returned to compressor intake of compression stage (C1) and stream which was purged from process to remove contaminants. The nitrogen recovery was 1078 lb/hr out of 1403 lb/hr (77%) in the feed. The process produced a liquid organic stream of 15428 lb/hr containing 14175 lb/h of isobutane (100% recovery) and 513 lb/hr of ethylene (95% recovery).