NOVELTY - Membrane contacting system comprises e.g. a gas compressor for pressing biogas containing gas dissolved in liquid under pressure which is higher than atmospheric pressure, a hollow module housing having an empty space, a hollow fiber membrane formed with a shell side installed outside spaced apart from inner wall of module housing along longitudinal direction of module housing and a tube side arranged along longitudinal direction, two caps formed with a partition wall isolated from shell side and communicating with tube side, and a tube side discharge port for discharging biogas.    USE - The system is useful for purifying biogas (claimed).    ADVANTAGE - The system has enhanced separation efficiency, induces cross-flow, and reduces boundary layer thickness of shell side and environmental pollution.    DETAILED DESCRIPTION - Membrane contacting system comprises a gas compressor (100) for pressing the biogas containing gas dissolved in liquid under pressure which is higher than the atmospheric pressure, a hollow module housing (210) having an empty space inside, a hollow fiber membrane formed with a shell side installed outside spaced apart from the inner wall of the module housing along the longitudinal direction of the module housing and a tube side arranged along the longitudinal direction, two caps formed with a partition wall isolated from shell side and communicating with the tube side, a tube side discharge port for discharging the biogas, a tube side inlet port for flowing the biogas compressed from the gas compressor and installed on both ends of the module housing, an absorbing membrane contactor module (200) equipped with a flow control tube (240) for moving the shell side discharge port and introducing the liquid into the shell side through a side hole, a partition formed at the middle, a shell side outlet port (242) for discharging the liquid, a degassing tank for degassing by strong the liquid discharged from the shell side outlet port in the form of pressure or vacuum, a gas discharging pipe for supplying the gas degassed from the degassing tank into the gas compressor and installed with a blower at the middle of a duct and connected to the other side of the gas compressor and top of the degassing tank, and a liquid circulating pipe for supplying the pressurized fluid into the absorbing membrane contactor module through a degassing membrane contactor module and installed with a pressurizing pump placed on one side of the duct connected with the shell side inlet port shell side outlet port. An INDEPENDENT CLAIM is also included for membrane contacting, comprising (a) compressing the biogas under a pressure greater than the atmospheric pressure using the gas compressor, (b) contacting membrane with the other side of the hollow fiber membrane by supplying the liquid into the shell side inlet port under a higher pressure higher than the pressurized biogas using the pressurizing pump, (c) primarily degassing the gas and the liquid within the degassing tank by supplying the liquid discharged from the shell side outlet port into the degassing tank, (d) supplying the gas from the degassing tank into the gas compressor through the gas discharging pipe, (e) contacting the membrane with one side of the hollow fiber membrane by supplying the primarily degassed liquid into the shell-side inlet port of the degassing membrane contactor module, and secondarily degassing by applying vacuum on the tube side of the degassing membrane contactor module using the vacuum pump, and (f) supplying the liquid discharged from the shell side outlet port of the degassing membrane contactor module into the absorbing membrane contactor module through the shell-side inlet port of the absorbing membrane contactor module and the fluid circulating tube.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the membrane contacting system.    Gas compressor (100)    Absorbing membrane contactor module (200)    Hollow module housing (210)    Flow control tube (240)    Shell side outlet port (242)