A novel fuzzy-logic control strategy minimizing N2O emissions. (15th October 2017)

• Record Type: Journal Article
• Authors: Boiocchi, Riccardo; Gernaey, Krist V.; Sin, Gürkan
• Is Part Of: Water research. Volume 123(2017)
• Page Start: 479
• Page End: 494
• Publication Date: 2017-10-15
• Subjects: Nitrous oxide -- Fuzzy-logic -- Wastewater -- Control -- Nitrogen; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.06.074
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: A novel control strategy for achieving low N2 O emissions and low effluent NH4 + concentration is here proposed. The control strategy uses the measurements of ammonium and nitrate concentrations in inlet and outlet of the aerobic zone of a wastewater treatment plant to calculate a ratio indicating the balance among the microbial groups. More specifically, the ratio will indicate if there is a complete nitrification. In case nitrification is not complete, the controller will adjust the aeration level of the plant in order to inhibit the production of N2 O from AOB and HB denitrification. The controller was implemented using the fuzzy logic approach. It was comprehensively tested for different model structures and different sets of model parameters with regards to its ability of mitigating N2 O emissions for future applications in real wastewater treatment plants. It is concluded that the control strategy is useful for those plants having AOB denitrification as the main N2 O producing process. However, in treatment plants having incomplete NH2 OH oxidation as the main N2 O producing pathway, a cascade controller configuration adapting the oxygen supply to respect only the effluent ammonium concentration limits was found to be more effective to ensure low N2 O emissions. Graphical abstract: Image 1 Highlights: A fuzzy-logic control strategy for low N2 O emissions is systematically developed. The control strategy is simulated for different N2 O formation mechanisms. Effluent quality and operation costs are considered while reducing N2 O emissions. The control strategy is found to reduce the N2 O produced by AOB denitrification.