METHOD FOR BIOLOGICALLY TREATING WASTE WATER

PROBLEM TO BE SOLVED: To provide a method for biologically treating waste water, in which when the waste water contains both of a sulfur-based COD component and a nitrogen component is treated under an oxygen-free sulfur oxidation condition, the rate of an oxygen-free sulfur oxidation reaction can be accelerated without necessitating a continuous or intermittent charge of a substance for activating metabolism of bacteria and without further necessitating membrane separation treatment.SOLUTION: The method for biologically treating waste water containing the sulfur-based COD component and the nitrogen component comprises the steps of: throwing a solid electron acceptor substance, which is functioned as an electron acceptor, in a reaction tank to proliferate denitrifying sulfur oxidation bacteria in the presence of the electron acceptor substance; and treating the proliferated denitrifying sulfur oxidation bacteria in the reaction tank under the oxygen-free sulfur oxidation condition so that the sulfur-based COD component in the waste water is oxidized and reduced and the nitrogen component is removed as a gas.SELECTED DRAWING: Figure 5 【課題】硫黄系ＣＯＤ成分及び窒素成分の両方を含む排水を無酸素的硫黄酸化条件下で処理するに際し、細菌の代謝を活性化させる物質を連続的又は断続的に投入する必要が無く、膜分離処理も不要でありながら、無酸素的硫黄酸化の反応速度を速めることができる排水の生物学的処理方法を提供する。【解決手段】硫黄系ＣＯＤ成分と窒素成分とを含有する排水の生物学的処理方法であって、反応槽内の排水中に電子受容体として機能する固体の電子受容体物質を投入し、この電子受容体物質の存在下に脱窒性硫黄酸化細菌を増殖させ、反応槽内で無酸素的硫黄酸化条件下に処理し、排水中の硫黄系ＣＯＤ成分を酸化させて低減させると共に、窒素成分を気体として除去する排水の生物学的処理方法である。【選択図】図５