Development of partial nitrification as a first step of nitrite shunt process in a Sequential Batch Reactor (SBR) using Ammonium Oxidizing Bacteria (AOB) controlled by mixing regime

- A Sequential Batch Reactor (SBR) was used to perform complete partial nitrification.
- A novel DO control strategy depending on using the mixing speed has been developed.
- The effect of DO, pH, alkalinity, FA and FNA acid have been evaluated.
- The SBR has been successfully running at nitrogen loading rate up to 1.2 kg/(m3.d).
- The SBR has achieved an ARE of 99% and a NAR of 93% at NLR of 1.2 kg/(m3.d).

Shortcut biological nitrogen removal is a non-conventional way of removing nitrogen from wastewater using two processes either nitrite shunt or deammonification. In the nitrite shunt process, the ammonia oxidation step stops at the nitrite stage, which is known as partial nitrification, then nitrite is directly reduced to nitrogen gas. Effective partial nitrification could be achieved by accumulating Ammonia Oxidizing Bacteria (AOB) and inhibiting Nitrite Oxidizing Bacteria (NOB). In this research, a novel control strategy has been developed to control the DO using the variable mixing regime in a suspended growth system using a Sequential Batch Reactor (SBR) in order to achieve a stable ammonia removal efficiency (ARE) and nitrite accumulation rate (NAR) at a high nitrogen loading rate (NLR). The new controlled SBR system has been successfully running at NLR up to 1.2 kg/(m3.day) and achieved an ARE of 98.6 ± 2.8% and NAR of 93.0 ± 0.7%.