ADVANCED WASTEWATER TREATMENT METHOD WITH THE BIOSOLIDS REDUCTION AND THE RECOVERY OF RBDCOD

A method for treating wastewater by combining the reduction of sludge with the recovery of RBDCOD(Readily Bio-Degradable COD) is provided to minimize the volume of sludge by solubilizing waste sludge and reducing the volume of a solubilized liquid, recover high concentration RBDCOD by selectively injecting magnesium and calcium into the solubilized liquid, and reduce chemical costs by using the recovered high concentration RBDCOD as a carbon source. In a wastewater treatment system comprising a wastewater treatment apparatus, a sludge reduction tank having an alkali treatment tank(15) and an ozone treatment tank(16), a fermentation tank(17), and a crystallization tank(19), a method for treating wastewater by combining the reduction of sludge with the recovery of RBDCOD comprises: a first step of alkali-treating waste sludge transferred from the wastewater treatment apparatus in the alkali treatment tank, and ozone-treating the alkali-treated waste sludge in the ozone treatment tank, thereby increasing solubilization ratio of the sludge to reduce the volume of the sludge; a second step of separating a liquid solubilized in the alkali treatment tank through a membrane(18) submerged into the alkali treatment tank, and transferring only a pure solubilized liquid to the crystallization tank; a third step of producing crystallized material in the crystallization tank from a solubilized liquid transferred from the alkali treatment tank; a fourth step of separating the crystallized material and recovering supernatant from the crystallization tank; and a fifth step of returning the supernatant recovered from the crystallization tank to the wastewater treatment apparatus to use the supernatant as a carbon source.