<；P>；PROBLEM TO BE SOLVED: To efficiently remove nitrogen components and phosphoric acid components contained in waste liquid, and to decolorize the waste liquid to obtain highly transparent and clean water. <；P>；SOLUTION: A waste liquid treatment method includes: a first separation process where Bacillus subtilis is supplied to a culture medium 12 of a hydroponic bed 10 for hydroponic cultivation of plants to remove the nitrogen components of the waste liquid discharged from the hydroponic bed 10 by the Bacillus subtilis； a second separation process where the waste liquid subjected to the first separation process and discharged from the hydroponic bed 10 is supplied to a treatment tank 1 and contaminants are coagulated and settled in the treatment tank 1 to decolorize the waste liquid and remove the phosphoric acid components； and a third separation process where the treated water treated in the second separation process is supplied to a treatment tank 3 filled with a porous material 4 whose minute voids are inoculated with Bacillus subtilis to remove the nitrogen components of the waste liquid by the Bacillus subtilis living in the treatment tank 3. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
