WASTEWATER TREATMENT METHOD

To provide a wastewater treatment method capable of continuously suppressing nitrification in a biological treatment of an organic waste water including a nitrogen compound, suppressing sludge floating in a settling tank generated due to nitrification, and attributing to stability and improvement of treated water quality.SOLUTION: In a wastewater treatment method including solid-liquid separation in a settling tank 20 of a sludge-containing water obtained by active sludge treatment of an organic waste water including a nitrogen compound in a biological treatment tank 10, returning a part of the sludge having been separated as a return sludge to the biological treatment tank, and treating the rest as an excess sludge, the wastewater treatment method is characterized by that a nitrification suppression agent containing a dithiocarbamate is added to the biological treatment tank 10 to suppress nitrification in the biological treatment tank 10.SELECTED DRAWING: Figure 1 【課題】窒素化合物を有する有機性排水の生物処理における硝化を持続的に抑制し、及び硝化に起因して発生する沈殿槽における汚泥浮上を抑制し、処理水質の安定及び向上に資する排水処理方法を提供する。【解決手段】窒素化合物を有する有機性排水を生物処理槽１０にて活性汚泥処理して得られる汚泥含有水を沈殿槽２０にて固液分離し、分離された汚泥の一部を返送汚泥として生物処理槽に返送し、残部を余剰汚泥として処理する排水処理方法であって、ジチオカルバミン酸塩を含む硝化抑制剤を生物処理槽１０に添加して、生物処理槽１０内での硝化を抑制することを特徴とする排水処理方法。【選択図】図１