小型合併処理浄化槽の嫌気ろ床における浮遊物捕捉と有機物除去の特性評価

抄録

Domestic wastewater treatment facilities, being called ‘Gappei-shori johkasou’, play an important role in the wastewater countermeasures of Japan. In small-scale gappei-shori johkasous for less than 50 persons'use, anaerobic filter process has been usually adopted as a primary treatment. Removal characteristics of organic compounds in this process have been reported, but the greater part of these results cannot be applied to the operation of johkasous as a practical matter, because of using artificial wastewater in the laboratory work. In this paper, therefore experimental investigations were carried out to make clear the removal characteristics of suspended solids, in addition to organic compounds, in this process of the actual johkasous.
The results showed that high SS removal ratio was achieved when netlike plates filter medium with a dimension of 100 mm×70 mm and ball-like skeleton filter medium were used in the 1st chamber and 2nd chamber of anaerobic filter tank, respectively. The BOD removal rate in this tank can be expressed by a linear reaction. Compared to a sedimentation/separation tank in which there is no filter medium, low molecule-ization of organic compounds in anaerobic filter tank progressed faster even though the HRT is three-fifth of that in sedimentation/separation tank. Most of the VFA in anaerobic filter tank was found to be decomposed into acetic acid and propyonic acid.