Abstract
Abrupt emission of nitrous oxide was observed in denitrification step of circulated nitrogen removal process treating domestic wastewater from combined sewerage system. Continuous monitoring of nitrous oxide emission revealed that such abrupt nitrous oxide emission occurred only when redox potential (ORP) exceeded+300mV. Dilution of influent by rain or snow was suspected reason for this emission, but rain or snow did not always resulted in such event. Laboratory scale experiments demonstrated the emission of nitrous oxide and accumulation of nitrate with intentional shock feeding of diluted influent. Addition of acetate after the feeding of diluted influent helped quick process recovery to the normal denitrification.
