energies Article Achieving Efficient and Stable Deammonification at Low Temperatures—Experimental and Modeling Studies Hussein Al-Hazmi 1,* , Xi Lu 1,2, Dominika Grubba 1 , Joanna Majtacz 1, Przemysław Kowal 1 and Jacek M ˛akinia 1 1 Faculty of Civil and Environmental Engineering, Gdansk University of Technology, 11/12 Narutowicza Street, 80-233 Gda´nsk,Poland;
[email protected] (X.L.);
[email protected] (D.G.);
[email protected] (J.M.);
[email protected] (P.K.);
[email protected] (J.M.) 2 Institute of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China * Correspondence:
[email protected] Abstract: The short-term effects of temperature on deammonification sludge were evaluated in a laboratory-scale sequencing batch reactor (SBR). Mathematical modeling was used for further evalu- ations of different intermittent aeration strategies for achieving high and stable deammonification performance at decreasing temperatures. As for the biomass cultivated at high temperatures (e.g., 30 ◦C), a higher temperature dependency (the adjusted Arrhenius coefficient θ for 11–17 ◦C = 1.71 vs. θ for 17–30 ◦C = 1.12) on the specific anammox growth rates was found at lower temperatures (11–17 ◦C) in comparison with higher temperatures (17–30 ◦C). Further evaluations of recovering the nitrogen removal efficiency at decreasing temperatures with the mathematical model by modifying the intermittent aeration strategies (aeration frequency (F) and the ratio (R) between non-aerated Citation: Al-Hazmi, H.; Lu, X.; (non-aer) phase and aerated (aer) phase durations) indicated that intermittent aeration with a pro- Grubba, D.; Majtacz, J.; Kowal, P.; longed non-aerated phase (e.g., R ≥ 4 regardless of F value) would help to maintain high and ◦ M ˛akinia,J.