METHOD FOR KEEPING ACTIVITY OF SLUDGE IN BIOLOGICAL NITRATION AND DENITRIFICATION TREATMENT APPARATUS

摘要

PURPOSE:To easily prevent the lowering in the activity of sludge, by holding the sludge in a biological nitration and denitrification treatment apparatus in the presence of a nitrate ion and/or a nitrite ion when the supply of load to said treatment apparatus is stopped. CONSTITUTION:In a biological nitration and denitrification apparatus, after steady operation is performed, the supply of raw water is stopped to stop the supply of load. In this state, sludges in treatment tank A-D are held in the presence of a nitrate ion and/or a nitrite ion. By this method, the activity of sludge is kept without lowering a nitration and denitrification speed.