BIOLOGICAL NUTRIENT REMOVAL SYSTEM USING ORGANIC ACIDS GENERATED FROM SEWAGE SLUDGE AND METHOD THEREFOR USING CONTINUOUS-TYPE THERMAL OXIDATION PROCESS

摘要

PURPOSE: To provide a biological nutrient removal system, which is able to decrease cost for maintenance by minimizing discharge of remaining sludge generated from a biological sewage advanced treatment process and provides high nitrogen removing efficiency even when load of flown-in organic materials is low, thereby simultaneously increasing removing efficiencies of nitrogen and phosphorous. CONSTITUTION: The system comprises an anaerobic tank (10) which receives effluent from a first settling reservoir (11) and mixes organic materials in the effluent with a solid-liquid separated sludge returned from a second settling reservoir (40) to release phosphorous in microorganism cell, a denitrification tank (20) which reduces nitrate nitrogen of the effluent flown-out from the anaerobic tank to nitrogen gas, an aeration tank (30) which nitrifies the effluent from the denitrification tank, a first return means (31) which returns inner sludge including highly concentrated nitrate nitrogen generated from the aeration tank to the denitrification tank, the second settling reservoir which solid-liquid separates the effluent discharged from the aeration tank and discharges lowly concentrated sludge to the outside, a second return means (41) which returns highly concentrated sludge in the second settling reservoir to the anaerobic tank, a concentration tank (50) which provides remaining sludge contained in the second settling reservoir is provided, a plurality of thermal oxidation reactors which decomposes and oxidizes the remaining sludge from the concentration tank into a liquid state, a catalyst injection and recovery means which injects catalyst to the thermal oxidation reactors and recovers the catalyst therefrom, a heating and pressurizing controller which controls the thermal oxidation reactors to be kept at a predetermined pressure and temperature, heaters heating the thermal oxidation reactors to the predetermined temperature, a oxidizing agent supplier supplying oxidizing agent to the thermal oxidation reactors to oxidize the sludge in the thermal oxidation reactors, a heat-exchange means which heat-exchanges high-temperature product and low-temperature concentrated sludge to cool down the high-temperature product and heat the low-temperature concentrated sludge, and a water storage tank which supplies organic acids generated from the thermal oxidation reactors to the denitrification tank and discharges side products through a lower part thererof.