The effect of oxygen supply on nitrogen removal via nitrite using stored substrate (PHB) as the electron donor in SBRs

•PHB was available as the electron donor for SND and endogenous denitritation.•Highest activity of SND happened at the beginning of famine phase.•Percent and rate of SND both decreased when oxygen supply increased reasonable.•Stronger oxygen supply preserved more PHB, benefiting endogenous denitritation.•Nitrogen removal for SBR was improved by enhancing oxygen supply during aeration.