<；P>；PROBLEM TO BE SOLVED: To provide a biological treatment method and apparatus reducing a disposal sludge amount by utilizing sludge generated in biological treatment as feed of fishes. <；P>；SOLUTION: In the biological treatment method for leading the sludge generated in a biological treatment system to a fish breeding water tank, the biological treatment system is divided into at least two processes, that is, the A process 2 of a preceding stage in which organic matter load is high and a B process 4 of a post stage in which it is low. Excess sludge 7 generated from the process 4 is led to the process 2, and the excess sludge 6 from the process 2 is led to the fish breeding tank 8. The excess sludge generated in the process 2 is led to the tank 8 after being modified and the modification is biologically performed by leading a part of outflow water of the process 2. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
