TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The closed biogas tank comprises an acid and alkali-resisting ceramic plate, a silicon rubber lining, a glass steel lining or a chloroprene rubber lining, for preventing corrosion and washing of the returning stirring, the feed port, a material liquid outlet, the biogas circulating returning port, the biogas outlet, a manhole, a sight hole, a temperature-measuring hole and a tank residue outlet are arranged on the inner surface. An expansion vermiculite powder cement paste thermal insulating layer is coated on the outer wall. The ammonium water spraying decompression de-phosphine device is made of polyvinyl chloride plastics or A3 steel, where the biogas enters the device from the upper side part, and the diluted ammonia water is sprayed from the top part into a flared opening via a shrinking opening at high speed in the same direction for accessing with the entered biogas, and then removing the phosphine in the biogas and generating the ammonium phosphate. The biogas is sprayed at a high speed by the ammonia water, where negative pressure is generated by synthetic spraying, and when the place is higher, the generated negative pressure is larger for decompressing in the biogas tank and good for biological fermentation. The desulfurizer filled with solid desulfurizing agent is a container in the shape of a cylinder, with its upper part and lower part being in the form of disc end sockets, and comprising ferric oxide scraps or manganese ore desulfurizing agent and the biogas enters the device from the lower part, passes through the desulfurizing layer and after the hydrogen sulfide is desorbed, and the methane is output from the upper part. The biogas tank residue and liquid circulating returning conveying pump is a corrosion-resisting centrifuging liquid conveying pump, where the biogas residue and biogas liquid in the whole biogas tank system are returned at a high speed from the feed port to the tank in forward direction by the centrifuging pump for making the device easy to feed, and at the same time the stirring the contents for improving the microbial fermenting rate, and the biogas liquid and the biogas residue are transported to a tank vehicle by a pump for transporting to a fertilizer factory for utilizing as organic fertilizers. The spherical (or a drum) methane tank is arranged at a place of 4 meters of standard height below the ground by using the feed port as the reference, where on one side, the biogas tank is beneficial for fecaluria in buildings and kitchen food sewage to flow into the biogas tank after processors. The biogas tank does not occupy the ground position, and is beneficial for maintaining the temperature. The water sealing gas storage cabinet is a metal cover floated on a water tank, and is capable of floating along with dosage of the methane, where both the inner wall and the outer wall are corrosion-resistant for solving the uneven gas dosage. A safe water seal is arranged on the gas inlet tube opening and the gas outlet tube opening respectively, for preventing gas tempering or returning accidents. ACTIVITY - Fertilizer.