Patent ID: 7014769

Claim:
A method for reducing nitrate concentration in wastewater in a wastewater treatment apparatus configured to define an aeration zone and a quiescent zone, wherein wastewater flows into said treatment apparatus, wherein said wastewater treatment apparatus further comprises at least one gas outlet positioned within said aeration zone to aerate said wastewater, said wastewater having a dissolved oxygen level, said method comprising the step of substantially ceasing gas flow into said aeration zone for a nitrate reduction period, where said length of said nitrate reduction period is sufficient to initiate nitrate metabolism and reduce nitrate concentrations within said aeration zone, and during said nitrate reduction period, mixing said wastewater in said aeration zone by flowing gas through said at least one gas outlet for an mixing period, said mixing period being of a duration to continue nitrate metabolism in said aeration zone during said mixing period without substantially raising said dissolved oxygen level.