TREATMENT OF EXCRETION SEWAGE

摘要

PURPOSE:To efficiently perform biological nitration and denitrification at a low dilution ratio and high load, by adding a floculant to excretion sewage to separate a separated solution with a BOD/N ratio of 2.5-3.5 and applying biological nitration and denitrification treatment to said separated solution. CONSTITUTION:Excretion sewage is introduced into a reaction tank 1 and an inorg. flocculant and/or a cationic org. flocculant 8 are injected into said reaction tank 1 while a pH control agent 9 is injected thereinto if necessary to perform flocculation reaction under stirring. Next, a nonionic or anionic org. synthesis agent 10 is injected in a second reaction tank 2 if necessary to grow floc under stirring and the solid-liquid separation is performed by a solid-liquid separation means 3 such as a concentrator. Separated sludge 11 is discharged from the solid-liquid separation means 3 and the separated solution 12 is introduced into a denitrification tank 4 along with return sludge 13 and a return nitrated solution 14 and mixed with activated sludge containing denitriding bacteria in the tank while the resulting mixture is gently stirred in an oxygen blocked state to perform denitrification treatment.