Patent ID: 6444125
Filing Date: 2002-09-03
Classification: C02F,Y10S

Abstract:
A method of treating a waste water for removing nitrogen and phosphorus comprising the following steps carried out repeatedly in a system comprising at least a pair of reaction basins with an intermittent aeration means, a clarifier for precipitating reacted waste water from the reaction basins, and a filtering means equipped between the reaction basins:introducing a raw waste water into a first reaction basin where denitrification and release of phosphorus are carried out in an anaerobic condition, discharging the waste water through the filtering means into a second reaction basin where nitrification and decomposition of organisms are carried out in an aerobic condition, and discharging the treated waste water through the clarifier and returning a sludge into the second reaction basin (phase A); introducing a raw waste water into the second reaction basin where an aerobic reaction is carried out in an aerobic condition, and discharging the treated waste water through the clarifier and returning a sludge into the second reaction basin, while in the first reaction basin, removing phosphorus through luxury uptake of the phosphorus into the sludge in an aerobic condition without inflow and outflow (phase A-1) introducing a raw waste water into the second reaction basin where denitrification and release of phosphorus are carried out in an anaerobic condition, discharging the waste water through the filtering means into the first reaction basin where nitrification and decomposition of organisms are carried out in an aerobic condition, and discharging the treated waste water through the clarifier and returning a sludge into the first reaction basin (phase B); and introducing a raw waste water into the first reaction basin where an aerobic reaction is carried out in an aerobic condition, and discharging the treated waste water through the clarifier and returning a sludge into the first reaction basin, while in the second reaction basin, removing phosphorus through luxury uptake of the phosphorus into the sludge in an aerobic condition without inflow and outflow (phase B-1).