抄録
The comparative study was made to select better chemical for simultaneous phosphorusremoval in nitrified liquor recycling nitification-denitrification process. Alminum sulfate (alum) andpolyalminum chloride (PAC) were exzamined because of their popularity as the chemicals for simultaneousphosphorus removal in Japan. Experimental works were carried out for a year in Kyotoadvanced wastewater treatment pilot plant, using 2 series biological treatment facilities. Both alumand PAC gave excellent results upon the phosphorus removal, but some differences were observed innitrification and slude characteristics. Nitrification was deteriorated more severely with alum than PAC. In the alum dosed series, occasional stops of the nitrification were observed especially in winterseason, resulting from sudden drops of the water temperature. But in the PAC dosed series, suchphenomena were not observed even in winter season. Regarding the thickenability and dewaterabilityof the generated sludge, the alum dosed sludge exhibited a little better properties than the PAC dosed one.
