Model predictive control of partial nitrification via nitrous oxide (N2O) emission monitoring

• N2O emission monitoring was used for the partial nitrification optimization.
• The off-gas “dry” sensor of N2O emission was used.
• partial nitrification can be improved by N2O emission monitoring.

The successful operation of partial nitrification relies on creating the optimal condition in which the ammonium oxidizing bacteria (AOB) is favoured and nitrite oxidizing bacteria (NOB) is inhibited. The fluctuation of influent load means the optimal condition varies dynamically. The routine monitoring such as dissolved oxygen (DO), nitrite and ammonium concentration is usually used for the system optimization. The sensors used for these routine monitoring are usually submerged in a hostile activated sludge environment and are subjected to sensor fouling. In this paper, the non-invasive off-gas nitrous oxide (N2O) monitoring was used for the optimization of partial nitrification in a laboratory scale bioreactor. The results indicated that N2O emission can be used as a quantitative tool for the optimization of partial nitrification process. The N2O emission data was used as feedback information to derive a more accurate model, which can then be used in the partial nitrification optimization.