2005 年 52 巻 4 号 p. 167-171
The environmental problems of eutrophication in the closing area of the sea increased oxygen demands in surface water and acidification. Total nitrogen and phosphorous are responsible for an eutrophication and the advanced sewage treatment for nitrogen is more necessary.
We used the polysulphone hollow fiber with pore of 0.1 mm as the supporter for the BOD oxidizing bacteria, nitrifying bacteria and denitrifying bacteria. These bacteria were immobilized on the surface of the hollow fiber through the medium of polyvinyl alcohol. The fiber modules were furnished in the tubular reactor and the sewage was introduced to the outer surface of the fiber. Oxygen for BOD oxidation and nitrification and nitrogen for denitrification were delivered from the hollow fiber's inner side. The continuous sewage treatment was put in operation by combination of the hollow fiber reactor in series, that is BOD oxidation reactor, nitrification reactor and denitrification reactor. When the artificial wastewater containing BOD (100 mg-BOD/L) and ammonium sulfate (20 mg-N/L) was fed, BOD oxidation rate of 10 g-BOD/m2/h, nitrification rate of 0.35 g-N/ m2/h and denitrification rate of 0.4 g-N/m2/h were attained. These rates were higher than the standard activated sludge process. Consequently, the hollow fiber reactor was considered very effective for removal of BOD and nitrogen in the sewage.
Since superiority of hollow fiber bioreactor was demonstrated in laboratory, we installed the bioreactor about 20 times as large as laboratory scale reactors in the sewage treatment plant and conducted feasibility study by integrated continuous sewage treatment. Thus we have confirmed the bioreactor of the present method to be applicable to the treatment of actual sewage.