METHOD AND APPARATUS FOR TREATING EXCRETION SEWAGE

摘要

PROBLEM TO BE SOLVED: To improve the quality of treated water while reducing cost of membrane washing by performing ozone injection treatment between a sedimentation separation tank and the circulating tank or membrane supply tank to a membrane filter apparatus of a rear stage. SOLUTION: Excretion sewage is circulated between a denitrification tank 2 and a nitrification tank 3 to be subjected to anaerobic nitrification and denitrification treatment and the treated liquid is subjected to solid-liquid separation treatment in a membrane filter apparatus 4 and the obtained biologically treated water 5 is transferred to a flocculation tank 7. An inorg. flocculant 6 is added to the biologically treated water 5 in the flocculation tank 7 to flocculate an SS component containing phosphate ions and COD and the formed flocs are separated into sedimented sludge and a supernatant liquid in a sedimentation separation tank 8 and the sedimented sludge is transferred to a sludge treatment process and dehydrated to be incinerated. Ozone 9 is directly injected in the supernatant liquid from an ozone generator 10 through an in-line and ozone dissolved water to be treated is sent into a circulating tank 11 and supplied to a membrane filter apparatus 14 from the circulating tank 11 to be subjected to solid-liquid separation treatment. Filtered water 15 is transferred to an activated carbon adsorbing tower 17.