N(2)O production during nitrogen removal via nitrite from domestic wastewater: main sources and control method.

Nitrite has been commonly recognized as an important factor causing N(2)O production, which weakened the advantages of nitrogen removal via nitrite. To reduce and control N(2)O production from wastewater treatment plants, both long-term and batch tests were carried out to investigate main sources and pathways of N(2)O production during nitrogen removal via nitrite from real domestic wastewater. The obtained results showed that N(2)O production during nitrogen removal via nitrite was 1.5 times as much as that during nitrogen removal via nitrate. It was further demonstrated that ammonia oxidization were main source of N(2)O production during nitrogen removal from domestic wastewater; whereas, almost no N(2)O was produced during nitrite oxidization and anoxic denitrification. N(2)O production during nitrogen removal via nitrite decreased about 50% by applying the step-feed SBR, due to the effective control of nitrite and ammonia, the precursors of N(2)O production. Therefore, the step-feed system is recommended as an effective method to reduce N(2)O production during nitrogen removal via nitrite from domestic wastewater.