Application of dissolved oxygen, oxidation reduction potential and PH value as control parameters in A2N-SBR process

A₂N-SBR process solves the problems in the conventional nitrogen and phosphorus removal systems, such as the sludge age conflict and competition for carbon source between phosphorus removal bacteria and nitrogen removal bacteria. In order to save more energy and achieve the on-line control of A₂N-SBR process, the ORP, DO, pH variations during the anaerobic, aerobic, anoxic and post aerobic stages were studied. The results showed that the appearance of pH flat indicated the end of phosphorus release in the anaerobic phase. In the aerobic stage, the inflexion point of pH and the abrupt ascending point of DO and ORP indicated the nitration was finished. An inflexion point of pH was observed when the denitrifying phosphorus removal was finished. The variations of ORP, DO, pH had good correlations with the phase transitions.