A contaminant removal subsystem, comprising: a first gas-liquid hollow-fiber membrane contactor-separator; a second gas-liquid hollow-fiber membrane contactor-separator downstream of the first gas-liquid membrane contactor-separator; and a third gas-liquid hollow-fiber membrane contactor-separator downstream of the second gas-liquid membrane contactor-separator; wherein the first gas-liquid membrane contactor-separator is configured to: receive a clean ionic absorbent liquid; and discharge a used ionic absorbent liquid; wherein the second gas-liquid membrane contactor-separator is configured to: receive the used ionic absorbent liquid discharged from the first gas-liquid membrane contactor-separator; receive a first sweep gas; discharge a first contaminant, from the used ionic liquid absorbent, for recovery and reuse; and discharge a partially regenerated ionic absorbent liquid; wherein the third gas-liquid membrane contactor-separator is configured to: receive the partially regenerated ionic absorbent liquid discharged from the second gas-liquid membrane contactor-separator; receive a second sweep gas; and discharge a second contaminant, from the partially regenerated ionic liquid absorbent, for recovery and reuse; and discharge a cleaned ionic absorbent liquid which is returned to the first gas-liquid membrane contactor-separator, wherein the subsystem further comprises: a condenser and a water separator located in the first sweep gas stream downstream of the second gas-liquid membrane contactor-separator; a water vaporizer configured to receive condensed water from the water separator and discharge water vapor as first sweep gas to the second gas-liquid membrane contactor-separator; a condenser and a water separator located in the second sweep gas stream downstream of the third gas-liquid membrane contactor-; and a dehumidifier configured to receive carbon dioxide and/or water vapor from the water separator in the first sweep gas stream and return the dehumidified sweep gas upstream of the condenser, wherein the water vaporizer is further configured to receive condensed water from the second sweep gas stream discharged from the third gas-liquid membrane contactor-separator. a first gas-liquid hollow-fiber membrane contactor-separator; a second gas-liquid hollow-fiber membrane contactor-separator downstream of the first gas-liquid membrane contactor-separator; and a third gas-liquid hollow-fiber membrane contactor-separator downstream of the second gas-liquid membrane contactor-separator; wherein the first gas-liquid membrane contactor-separator is configured to: receive a clean ionic absorbent liquid; and discharge a used ionic absorbent liquid; receive a clean ionic absorbent liquid; and discharge a used ionic absorbent liquid; wherein the second gas-liquid membrane contactor-separator is configured to: receive the used ionic absorbent liquid discharged from the first gas-liquid membrane contactor-separator; receive a first sweep gas; discharge a first contaminant, from the used ionic liquid absorbent, for recovery and reuse; and discharge a partially regenerated ionic absorbent liquid; receive the used ionic absorbent liquid discharged from the first gas-liquid membrane contactor-separator; receive a first sweep gas; discharge a first contaminant, from the used ionic liquid absorbent, for recovery and reuse; and discharge a partially regenerated ionic absorbent liquid; wherein the third gas-liquid membrane contactor-separator is configured to: receive the partially regenerated ionic absorbent liquid discharged from the second gas-liquid membrane contactor-separator; receive a second sweep gas; and discharge a second contaminant, from the partially regenerated ionic liquid absorbent, for recovery and reuse; and receive the partially regenerated ionic absorbent liquid discharged from the second gas-liquid membrane contactor-separator; receive a second sweep gas; and discharge a second contaminant, from the partially regenerated ionic liquid absorbent, for recovery and reuse; and discharge a cleaned ionic absorbent liquid which is returned to the first gas-liquid membrane contactor-separator, wherein the subsystem further comprises: a condenser and a water separator located in the first sweep gas stream downstream of the second gas-liquid membrane contactor-separator; a water vaporizer configured to receive condensed water from the water separator and discharge water vapor as first sweep gas to the second gas-liquid membrane contactor-separator; a condenser and a water separator located in the second sweep gas stream downstream of the third gas-liquid membrane contactor-; and a dehumidifier configured to receive carbon dioxide and/or water vapor from the water separator in the first sweep gas stream and return the dehumidified sweep gas upstream of the condenser, a condenser and a water separator located in the first sweep gas stream downstream of the second gas-liquid membrane contactor-separator; a water vaporizer configured to receive condensed water from the water separator and discharge water vapor as first sweep gas to the second gas-liquid membrane contactor-separator; a condenser and a water separator located in the second sweep gas stream downstream of the third gas-liquid membrane contactor-; and a dehumidifier configured to receive carbon dioxide and/or water vapor from the water separator in the first sweep gas stream and return the dehumidified sweep gas upstream of the condenser, wherein the water vaporizer is further configured to receive condensed water from the second sweep gas stream discharged from the third gas-liquid membrane contactor-separator.