NOVELTY - A purifier has a storage tank (11) for storing natural water, a soil contact processing tank (12), and a humus tree treatment tank (13). Tank (12) is filled with volcanic ash soil granulated baked material. Tank (13) is filled with humus tree (2) as nutrient of bacteria. The baked material is obtained by granulating amber soil (1) or kanuma soil to diameter of 5-50 mm, adjusting moisture content to 40-150%, heating at 300-750degreesC, and maintaining for 10 minutes or more. The baked material has specific surface area of 50-150 m2/g and dry density of 0.7-1.2 g/cm3.    USE - For purifying phosphorus and nitrogen-containing wastewater, such as livestock farming wastewater and secondary treated wastewater of sewage.    ADVANTAGE - The purifier efficiently enables removal of nitrogen and phosphorus with high reliability and stability for long period of time.    DETAILED DESCRIPTION - A purifier has a storage tank (11) for storing natural water, a soil contact processing tank (12) connected to the downstream side of storage tank, and a humus tree treatment tank (13) connected to the downstream side of soil contact processing tank. The purifier purifies wastewater containing phosphorus and nitrogen by contacting wastewater with volcanic ash soil. The soil contact processing tank is filled with volcanic ash soil granulated baked material. The humus tree treatment tank is filled with humus tree (2) as nutrient of bacteria. The volcanic ash soil granulated baked material is obtained by granulating amber soil (1) or kanuma soil to diameter of 5-50 mm, adjusting moisture content to 40-150%, heating at 300-750degreesC, and maintaining for 10 minutes or more. The granulated baked material has specific surface area of 50-150 m2/g and dry density of 0.7-1.2 g/cm3.    INDEPENDENT CLAIMS are also included for:    (1) purification of phosphorus and nitrogen-containing wastewater; and    (2) volcanic ash soil granulated baked material.    DESCRIPTION OF DRAWING(S) - The figure shows the block diagram of purifier.    Amber soil (1)    Humus tree (2)    Porous absorption material (3)    Storage tank (11)    Soil contact processing tank (12)    Humus tree treatment tank (13)    Porous treatment tank (14)