NOVELTY - A gas-purification apparatus (10) has treatment tank (11), gas supply unit (16) for circulating original gas (1) containing organic silicon group impurity and sulfur group impurity, and evacuation unit (19) for evacuating tank. Apparatus contains MCM-41, USY, MCM-48, and USM as organic silicon group impurity adsorption agent, and silicalite as sulfur group impurity adsorption agent.    USE - Used in sewage-purification processing facility for purifying original gas such as biogas and discarded heat-cracked gas (claimed) obtained from waste materials such as garbage. Purified gas such as methane gas is used as fuel for incineration system, gas engine, micro-gas turbine, and fuel cell used for electric power generation.    ADVANTAGE - The gas-purification apparatus is compact, and economically and simply provides purified gas with high purity and yield. The gas-purification apparatus has improved processing efficiency. Carbon dioxide recovered from the original gas is effectively utilized for various raw materials.    DETAILED DESCRIPTION - A gas-purification apparatus (10) has a treatment tank (11), a gas supply unit (16) for circulating original gas (1) containing organic silicon group impurity and sulfur group impurity from one side of treatment tank to other side, and an evacuation unit (19) for carrying out evacuation of the treatment tank. The one side in the treatment tank, and the other side are optionally divided by containing MCM-41, USY, MCM-48, and USM as organic silicon group impurity adsorption agent (12), and silicalite as sulfur group impurity adsorption agent (13).    An INDEPENDENT CLAIM is also included for sewage-purification processing facility, which has the gas-purification apparatus, which obtains methane as a purified gas by converting the original gas into sewage gas generated from sludge of sewage. The purified gas separated from original gas with the gas-purification apparatus is used as fuel for an incineration system. Incineration processing of the organic silicon group impurity and sulfur group impurity separated from original gas with the gas-purification apparatus is carried out with the incineration system.    DESCRIPTION OF DRAWING(S) - The figure shows an outline block diagram of the gas-purification apparatus. (Drawing includes non-English language text).    original gas (1)    gas-purification apparatus (10)    treatment tank (11)    organic silicon group impurity adsorption agent (12)    sulfur group impurity adsorption agent (13)    gas supply unit (16)    evacuation unit (19)