Effect of aeration rate on CANON reactors with different carriers

The effect of aeration rate on the efficiency of CANON(completely autotrophic nitrogen-removal over nitrite) process was studied to improve total nitrogen removal of ammonium-rich wastewater.With simulated wastewater as influent,two kinds of CANON reactors,which used sponge and modified polyethylene as carriers respectively,were studied in tests.The results showed that total nitrogen removal efficiency and removal load were closely related to aeration rate,the increase of aeration rate would improve total nitrogen removal of CANON reactor when aeration rate was less than the limiting aeration rate.For the CANON reactor which used sponge as carrier,when aeration rate was 35.8 m~3·m~(-3)·h~(-1),the total nitrogen removal efficiency reached the maximum value of 79.48%,and total nitrogen removal load was 2.32 kg·m~(-3)·d~(-1).When aeration rate was more than the limiting aeration rate,the effect on total nitrogen removal remained stable,because the structure of sponge protected the Anammox bacteria from inhibition by dissolved oxygen.With sponge as carrier,more biomass could be retained in the CANON reactor,especially for Anammox bacteria,which guaranteed the stable operation of the CANON reactor.For the CANON reactor which used modified polyethylene as carrier,when aeration rate was 6.3 m~3·m~(-3)·h~(-1),the total nitrogen removal efficiency reached the maximum value of 77.6%,and total nitrogen removal load was 1.01 kg·m~(-3)·d~(-1).When aeration rate was more than the limiting aeration rate,the effect on total nitrogen removal deteriorated because Anammox bacteria were inhibited by dissolved oxygen.Less biomass could be retained,so the reactor was less stable.