NOVELTY - A pressurization apparatus comprising a biogas inlet pipe having at least a biogas feeding mechanism, a biogas outlet pipe having at least a biogas cut-off mechanism, a washing water inlet pipe having at least a washing water pressurization device, and a washing water outlet pipe having at least a cut-off valve, is new.    USE - The apparatus is used for pressurizing a biogas in a gas washer by passing purified biogas through the cut-off mechanism of the outlet pipe, opening the cut-off valve of the washing water outlet pipe, passing pressurized biogas to the pressurization apparatus, and closing the cut-off valve (claimed).    ADVANTAGE - The apparatus is quicker and more effective compared to an apparatus with a single water pump. It has low maintenance and repair costs.    DETAILED DESCRIPTION - A pressurization apparatus for pressurizing biogas (210) comprises a biogas inlet pipe (211) having at least a biogas feeding mechanism (213), a biogas outlet pipe (221) having at least a biogas cut-off mechanism (222, 223), a washing water inlet pipe (231) having at least a washing water pressurization device (232), and a washing water outlet pipe (241) having at least a cut-off valve (242). It is operated by feeding pressurized washing water (230) to the pressurization apparatus containing biogas using the washing water pressurization device, passing purified biogas (220) through the cut-off mechanism, opening the cut-off valve when the water level in the pressurization apparatus having reached the upper limit, passing pressurized biogas to the pressurization apparatus through the biogas inlet pipe, and closing the cut-off valve of the washing water outlet pipe.    An INDEPENDENT CLAIM is also included for a method of constructing a pressurization apparatus for biogas.    DESCRIPTION OF DRAWING(S) - The figure shows a pressurization apparatus.    Nebulizer (202)    Biogas (210)    Biogas inlet pipe (211)    One-way valve (212)    Biogas feeding mechanism (213)    Purified biogas (220)    Biogas outlet pipe (221)    Biogas cut-off mechanism (222, 223)    Washing water (230)    Washing water inlet pipe (231)    Pressurization device (232)    Washing water outlet pipe (241)    Cut-off valve (242)    Carbon dioxide removal unit (243)    Driers (301)    Pressure tank (401)