APPARATUS AND METHOD FOR TREATING ORGANIC WASTE WATER

摘要

An apparatus for treating an organic waste water wherein two or more treating tanks each having a denitrification tank and a nitrification tank being connected in this order are connected in series, characterized in that it further has lines for supplying the water to be treated separately to denitrification tanks of respective steps, a means for filtrating and separating at least a part of an activated sludge mixture fluid in at least one nitrification tank, and lines for supplying at least a part of a concentrated sludge mixture fluid formed by the above filtration and separation treatment to denitrification tanks. The apparatus allows the solution of the problem involving contradiction that in a system for treating an organic waste water by denitrification and nitrification, the increase of the amount of the circulation from a nitrification tank to a denitrification tank in order to achieve a high nitrogen removal rate lowers the denitrification capability of the denitrification tank, due to the inflow of a nitrified liquid having a high dissolved oxygen content to the denitrification tank, and, as a result, allows the achievement of an enhanced nitrogen removal rate without lowering of the denitrification capability of the denitrification tank.