EFFECT OF AERATION RATES ON THE TREATED WATER QUALITY OF GAPPEI-SYORI JOHKASOU

The effect of aeration rates on the treated water quality of gappei-syori Johkasou was evaluated by changing the setting condition for the blowing air rates of 11 household gappei-syori Johkasou; and the relations among all measured quality indexes were analyzed through correlation and principal component analyses. Of the total 11 Johkasou targeted, 7 Johkasou showed improvement in their performance through changing the blowing air rates alone, reflected by concentration decreases of BOD and elevations of transparency for the water after treatment. The results of correlation and principal component analyses showed that, in addition to SS, VSS and organic nitrogen, particles in the size range of 0.5-1.0μm, ORP and nitrification were closely related to the organic loading represented by BOD and C-BOD. The changes in the concentration of DO brought about by changing the blowing air rates was shown to positively affect the settling property of sludge.