| 摘要 |
PURPOSE:To make it possible to treat sewage stably for a long period of time by a method wherein a filler material layer arranged within a purifying tank is constituted from a freely extensible and contractible material and, by changing a sewage flow passage structure, the growth and the exfoliation of a biological membrane adhered to a filler material layer are carried out in turn. CONSTITUTION:A freely extensible and contractible filler material layer 3 is formed by adhering a synthetic resin corrugated plate or by forming a cut out portion in a synthetic resin flat plate and inlaying respectively at right angle in an opposedly contact manner to form a square pillar like flow passage. If the purifying operation of sewage is carried out by using this filler material layer, firstly, a biological membrane adhered to this filler material layer 3 starts the proliferation and the thickening gradually. But, when the lowering of purifying efficiency according to the thicknening of the biological membrane does not advance remarkably, if a handle 5 is rotated, a filler material layer 3 is totally contracted and the cross area of a sewage recirculating circuit formed in a filler material layer 3 is reduced. Therefore, the recirculating speed of sewage passing through the filler material layer 3 becomes larger to release the adhered and thickened biological membrane and, because the structure of a filler material layer 3 is changed, can be released mechanically. |
