Nitritation and denitritation of domestic wastewater using a continuous anaerobic-anoxic-aerobic (A²O) process at ambient temperatures
2010
Zeng, Wei | Li, Lei | Yang, Yingying | Wang, Shuying | Peng, Yongzhen
In a continuous anaerobic-anoxic-aerobic (A²O) process treating domestic wastewater at ambient temperatures, nitritation was achieved through a combination of short aerobic actual hydraulic retention time (AHRT) and low dissolved oxygen (DO) levels (0.3-0.5mg/L). The nitrite accumulation rate was about 90% and ammonia removal efficiency was over 95%. With respect to total nitrogen removal, nitritation-denitritation at low DO levels of 0.3-0.5mg/L was essentially equal to the complete nitrification-denitrification at DO levels of 1.5-2.5mg/L with the addition of external carbon sources. Regardless of low DO operation, sludge bulking did not occur since the sludge volume index was below 150ml/g. Real-time PCR assays showed that in response to complete and partial nitrification modes, the numbers of ammonia oxidizing bacteria population were 5.28×10⁹ cells/g MLVSS and 3.95×10¹⁰ cells/g MLVSS, respectively. Achievement of nitritation-denitritation is highly beneficial to the treatment of domestic wastewater in terms of lower carbon requirements and reduced aeration costs.
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