A device or apparatus for contacting a liquid with a gas is provided. The device or apparatus has at least one gas inlet for introducing the gas into the liquid and a fiber housing with at least one liquid inlet and at least one liquid outlet. The fiber housing is surrounding and defining an outer bound for a plurality of fibers extending longitudinally in the fiber housing, whereby longitudinally extending interspaces are provided between the fibers. These interspaces thereby define flow passages for the liquid and gas. There is also provided a system and a method for contacting a liquid with a gas.