APPARATUS FOR BIOLOGICALLY TREATING ORGANIC WASTE LIQUID

摘要

A digested sludge of an organic waste liquid is concentrated and the concentrated sludge is returned into a biological treatment tank. Thus, digestion is efficiently carried out and the reduction ratio of the sludge is elevated. An organic waste liquid is fed into a biological treatment tank (1) and biologically treated therein. A portion of the digested sludge in the biological treatment tank (1) is withdrawn via a pipe (2), a pump (3) and another pipe (4) and then concentrated by a centrifugal machine (5). The concentrated sludge having been concentrated by the centrifugal machine (5) is fed into a mixing tank (6). The separated liquid is discharged from the apparatus via a pipe (7). A portion of the sludge (the unfractionated sludge) is introduced into a centrifugal machine (13) and centrifuged into a fraction containing suspended organic solids at a higher ratio and the other fraction containing suspended organic solids at a lower ratio. The low-organic fraction is discharged from the biological treatment apparatus via a pipe (15). The high-organic fraction can be fed into the mixing tank (6) via a pipe (14). The unfractionated sludge in the pipe (10) can be fed into the mixing tank (6) via a pipe (16) that is branched from the pipe (10), a valve (17) and another pipe (18).