Development of a continuous single tank nitrification-denitrification process

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Continuous single tank nitrification-denitrification process was developed to overcome the lssues pointed out in the conventional nitrogen removal processes. Drafttube type reactor was applied to sewage treatment and operational and design parameters of this reactor were examined. Ability of aerobic denitrifier is utilized was also examined.Empirical equations on velocity of circulating flow and K_La in the draft-tube type reactor are constructed both experimentally and theoretically. Based on the results, continuous sewage treatment was performed. The results showed that 70-75% TN removal efficiency can be obtained in this reactor. It was also found that both aerobic zone ratio and anoxic zone ratio are necessary to be kept more than 0.35 to obtain more than 80% of both nitrification and denitrification ratio. C / N ratio in the influent is necessary to be kept about 3 (mg C / mgN). The ratio of draft tube diameter to reactor diameter (D_1 / D_0) influences TN removal efficiency. In the reactor which has effective depth of 4m, more than 70% TN can be removed only when D_1 / D_0 is 0.19. Analysis of DO decreasing rate in the annulus part shows that the higher effective depth of the reactor is, the easier both aerobic and anoxic zone can be created. Operational and designed parameters for nitrogen removal in the draft tube type reactor were examined extnsively by using the mathematical model.A selective determination method of the aerobic denitrifier in the mixed liquor is developed with immuno assay. Examination by using the mathematical model shows that the ratio of aerobic denitrifier increased in the mixed liquor by increasing BODMLSS loading rate.