Abstract: Provided is a wastewater treatment technology (in particular, pretreatment technology) that, in comparison to existing technologies, can reduce the quantity of sludge generated as a result of processing wastewater that contains fluorine and silicon. Before adding a calcium compound to wastewater that contains fluorine and silicon and performing coagulation-sedimentation treatment on said wastewater, as a pretreatment, sodium hydroxide is added to the wastewater (first reaction tank 1), sodium silicofluoride is precipitated, and the precipitate sodium silicofluoride is removed via solid-liquid separation (first sedimentation tank 2).

Abstract: An object (first object) of the invention is to provide a waste water treatment technology (pretreatment technology in particular) which makes it possible to recover fluorine at a high recovery rate as highly pure calcium fluoride, without diluting waste water containing fluorine and silicon, i.e. to recover fluorine from high-concentration waste water containing fluorine and silicon. Waste water containing fluorine and silicon is supplied to a pH controlling tank 1 and sodium hydroxide (NaOH) is added thereto, with the result that sodium silicate is precipitated. Thereafter, the waste water is supplied to a solid-liquid separator 2 so that solid-liquid separation of sodium silicate is conducted.

Abstract: The present invention provides a method for treatment of wastewater containing organic sulfur compounds The method includes introducing the wastewater into an apparatus body equipped with a fixed bed in which fixed carriers for the attachment of microorganisms are filled and a fluidized bed in which flowing carriers for the attachment of microorganisms are flown, and enabling the wastewater to flow through the fluidized bed towards the fixed bed so that the wastewater is biologically treated by the fluidized bed and the fixed bed.

Abstract: The present invention provides a method for treatment of wastewater containing organic sulfur compounds The method includes introducing the wastewater into an apparatus body equipped with a fixed bed in which fixed carriers for the attachment of microorganisms are filled and a fluidized bed in which flowing carriers for the attachment of microorganisms are flown, and enabling the wastewater to flow through the fluidized bed towards the fixed bed so that the wastewater is biologically treated by the fluidized bed and the fixed bed.

Abstract: The present invention provides a method of treating water containing organic sulfur compounds. The method includes treating the water containing the organic sulfur compounds by adding wastewater containing a quaternary ammonium compound or wastewater containing an amine thereto. An apparatus for carrying out the above method is also provided.

Abstract: A method for treating water containing organic sulfur compounds comprises adjusting the pH value of the water in a pH adjustment tank, biologically treating the water in a biological treatment tank, adjusting the pH value of the water to be alkaline at any places in the biological treatment tank, maintaining the dissolved oxygen concentration of the water to 2 mg/L or higher at any places in the biological treatment tank, and supplying a part of the water to the pH adjustment tank for a further treatment. An apparatus for carrying out the above method is also provided.