Application of real-time nitrogen measurement for intermittent aeration implementation in a biological nitrogen removal system: performances and efficiencies

Several automatic strategies for aeration control have been investigated so far to favour a significant decrement of energy consumptions in biological processes in wastewater treatment plants. Above all, the intermittent aeration process has demonstrated to have several advantages. This work reports the results of a case study made in a small municipal wastewater treatment plant where an intermittent aeration control strategy based on the on-line measurement of real time nitrogen forms has been implemented to optimize the nitrogen removal and the energy consumption in an activated process. High organic removal efficiency was achieved during the whole experimental period. Results indicated that nitrogen removal efficiency has been improved, especially during winter months, by the control strategy adopted that helped to determine the perfect length for the nitrification and denitrification phases. The intermittent aeration process increased the activity of the biomass, further selecting phosphate accumulating bacteria and improving the growth of bacteria able to internally store carbon source. Excellent effects were achieved on energy and chemical consumption, with a reduction of about 15% and 23%, respectively. Finally, a 12% reduction of sludge production was also detected.