a housing unit comprising a first fluid inlet for introduction of a first fluid, a first fluid outlet for discharge of the first fluid, a second fluid inlet for introduction of a second fluid, and a second fluid outlet for discharge of the second fluid, a humidity of the first fluid introduced through the first fluid inlet being different from a humidity of the second fluid introduced through the second fluid inlet;

at least one first cartridge installed in the housing unit, the at least one first cartridge having a plurality of hollow fiber membranes therein; and

at least one second cartridge installed in the housing unit, the at least one second cartridge being filled only with a gas filter configured to capture harmful gas included in at least one of the first and second fluids, the gas filter having a different shape from the hollow fiber membranes, the harmful gas comprising nitrogen oxide (NO_x), sulfur oxide (SO_x), ammonia (NH₃), or a mixture of two or more thereof.