生物ろ床の浄化特性と優勢バクテリアフローラの変遷 : 充てん塔式ろ床法による有機性廃水の処理(第4報)

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Three biological filters different only in the depth-1,2 and 3 m-were seeded with Flavobacterium sp. S78 which grows well aroung the polypropylene filter media(average diameter of 25 mm) used in this study. To develop and maintain the biological film, fresh synthetic wastewater consisting of glucose, Polypepton, and KH_2PO_4 had been recirculated every day on a batch basis keeping several controllable factors constant as follows; ambient air temperature of 25℃, wastewater temperature of 20℃, applied organic loading of 1.4 kg COD/m^3/day, recirculation flow rate of 180 m^3/m^2/day and forced ventilation flow rate of 180 m^3/m^2/day from the top the filter.During the course of operation, the changes of the dominant bacteria flora in the biological film were investigated in connection with the purification properties of biological filters.It took about two weeks for the purification capacities of each biological filter to reach nearly constant levels after the flucturation of the early working-in period, which was attributable of the following fact ; the biological film developed early by the forced inoculation of Flavobacterium sp. S78 was dislodged from the media and new film was successively regenerated by different types of bacteria.The relationship between two variables-filter depth and hydraulic loading-and purification efficiency was followed with the general form (C_e/C_i=10^<-kDm/Q-n>) of the removal equation developed by Howland and Schulze, The rate coefficient k, and the exponents m and n, which are considered to depend on the nature of wastewater and the other conditions, were 0.49,1.34 and 0.69,respectively, under the conditions established in this study. It was found as well that COD removal capacity could be related linearly to the COD loading applied to the filter (COD removal capacity = 0.135 COD loading + 1.5), assuming the removal capacity by biosorption to be about 1.5 kg COD/m^3/day. These results suggest that the three biological filters used in this study had closely similar properties from the viewpoint of purification.Sixty one strains were isolated from various levels of each filter, with members of the genera Arthrobacter, Flavobacterium, Klebsiella, Pseudomonas, Alcaligenes and Bacillus as the predominant types. The apparent changes been effected in the dominant bacteria flora established in the biological film of each filter throughout the operation. Flavobacterium, which was used as the inoculated source, was detectable only within the first two weeks and subsequently there were changes to other dominats : Pseudomonas and Alcaligenes via Klebsibella and Arthobacter for a 1 m depth biological filter ; unidentified genus, Klebsiella, Alcaligenes, and Bacillus for both 2 and 3m depth biological filters. The changes from Flavobacterium to the other bacteria corresponded closely with the dislodgment of biological film developed in the early period from the media. Members of the genus Klebsiella and Alcaligenes were more prevalent bacteria than the others for all filters.
1980-05-25

生物ろ床の浄化特性と優勢バクテリアフローラの変遷 : 充てん塔式ろ床法による有機性廃水の処理(第4報)

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