Research on effect of simultaneous nitrification denitrification under step-feed with three-stage catching bed reactor

摘要

Three-stage catching bed reactor was used to treat domestic wastewater from residential area through the step feed in order to get high efficiency of simultaneous nitrification denitrification(SND). The effect of 3 influent flow rate distribution ratios (λ) on the removal of COD, NH4⁺-N and TN was investigated under the conditions of hydraulic retention time (HRT)=8h, DO=1.0∼2.0mg/L and sludge reflux rate of 100%. The removal efficiency of TN and NH4⁺-N reached at 70.9%, 96.4% separately when λ was 3∶4∶3; When λ was controlled in 4∶3∶3∶62.7% of average TN removal rate was obtained and the removal efficiency of NH4⁺-N was 95.8%; When λ was adjusted to 5∶3∶2, the removal efficiency of TN decreased to 58.5%. However, nitrification is still very good, 90.6% of average NH4⁺-N removal rate was achieved. And more than 90% of average COD removal rate was obtained under the three projects of flow rate distribution.