BIOLOGICAL DEPHOSPHORIZATION OF PHOSPHORUS-CONTAINING WASTE FLUID

摘要

PURPOSE:To biologically dephosphorize a phosphorus-containing fluid by a simple apparatus and operation even if no aeration treatment process is provided. CONSTITUTION:A fluid to be trated to which acetic acid is added from an org. matter adding passage 8 is introduced into a phosphorus discharge tank 1 from a supply passage 5 and mixed with return sludge to be held to an aerobic state to discharge phosphorus from sludge. The mixed fluid in the phosphorus discharge tank 1 is introduced into a denitrifying and dephosphorizing tank 2 and nitrous acid and/or nitric acid are added to the tank 2 from an addition passage 10 and an anaerobic state is kept to perform denitrification and dephosphorization. The mixed fluid in the denitrifying and dephosphorizing tank 2 is subjected to solid-liquid separation in a solid-liquid separation tank 3 and a part of separated sludge is returned to the phosphorus discharge tank 1 from a sludge return passage 4 and the remainder thereof is discharged as excess sludge.