Abstract: A system and method for organic wastewater treatment through denitrification and nitrification processes. The system for treating organic wastewater includes a multistage treatment tank having at least two stages in series. Each stage has a denitrification tank and a nitrification tank connected in this order. The system includes a pipe for distributing feed water to the denitrification tank in each stage, a device for filtering and separating at least a part of an activated sludge mixed liquor present in at least one nitrification tank, and a pipe for supplying at least a part of the concentrated sludge mixed liquor obtained by the filtration and separation treatment to the denitrification tank.

Abstract: The present invention overcomes mutually contradictory problems associated with a system for organic wastewater treatment through denitrification and nitrification processes, to the effect that when the circulating volume from the nitrification tank to the denitrification tank is increased to achieve high removal of nitrogen, the introduction of a nitrified fluid rich in dissolved oxygen causes a reduction in denitrification performance of the denitrification tank. Thus, the object of the present invention is to provide a system and method for organic wastewater treatment through denitrification and nitrification processes, which system and method achieve high removal of nitrogen without reducing the denitrification performance of denitrification tanks.

Abstract: A wastewater treatment process involves solids-liquid separation after biological treatment, in which solids-liquid separation of activated sludge can be more efficiently performed. A mixture of wastewater and activated sludge obtained after biologically treating raw wastewater is introduced into a solids-liquid separation tank containing a water-permeable filter immersed therein and a dynamic filter layer of sludge is formed on the surface of the water-permeable filter to give a filtrate from the water-permeable filter.

Abstract: The present invention has an object to provide a dynamic filter module which can inhibit deterioration of the filtration flux due to deposition of sludge inside the filter to stably give good treated water. In order to achieve such an object, the present invention provides, in one embodiment, a dynamic filter module for the separation of activated sludge having a water permeable filtration layer support material for forming a dynamic filtration layer as at least part of the surrounding wall of a support whose inside is hollow, the module having the filtration section having a water permeable filtration layer for forming a dynamic filtration layer, a filtrate water outlet arranged above and/or below the filtration section, and further having a sludge collection section having a sludge discharge outlet arranged below the filtration section.

Abstract: An object of the present invention is to provide a wastewater treatment process involving solids-liquid separation after biological treatment, in which solids-liquid separation of activated sludge can be more efficiently performed. In order to achieve-this object, the present invention provides a wastewater treatment process involving solids-liquid separation of the activated sludge mixed liquor obtained after biologically treating raw wastewater, comprising introducing raw water into a biological reaction tank to biologically treat it, then introducing the activated sludge mixed liquor treated in the biological reaction tank into a solids-liquid separation tank containing a water-permeable filter immersed therein and forming a dynamic filter layer of sludge on the surface of the water-permeable filter to give a filtrate from the water-permeable filter.