| Autor: |
Liu B; Faculty of Environmental Engineering, The University of Kitakyushu, 1-1, Hibikino Wakamatsu, Kitakyushu, Japan E-mail: hidenari-yasui@kitakyu-u.ac.jp., Terashima M; Faculty of Environmental Engineering, The University of Kitakyushu, 1-1, Hibikino Wakamatsu, Kitakyushu, Japan E-mail: hidenari-yasui@kitakyu-u.ac.jp., Quan NT; Department of Environmental Technology, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam., Ha NT; Department of Environmental Technology, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam., Van Chieu L; Department of Environmental Technology, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam., Goel R; Hydromantis Environmental Software Solutions, Inc., 407 King Street West, Hamilton, Ontario, Canada., Yasui H; Faculty of Environmental Engineering, The University of Kitakyushu, 1-1, Hibikino Wakamatsu, Kitakyushu, Japan E-mail: hidenari-yasui@kitakyu-u.ac.jp. |
| Abstrakt: |
Allylthiourea is a known specific inhibitor for ammonium oxidiser to suppress its oxygen uptake, and is commonly used for various kinds of batch respirometric tests to detect heterotrophic respiration in activated sludge. However, when high heterotrophs were present in the sample, it appeared the inhibitor was noticeably degraded and reached below the inhibition threshold after a couple of days, which resulted in overestimation of the heterotrophic respiration. The biological decomposition of the inhibitor was expressed with a Monod-type rate expression having a half-saturation coefficient of 980 mg-COD/L and maximum specific growth rate of 1.0 d -1 . The developed kinetic model, including the growth and decay of the heterotrophs and nitrifiers, indicated that the ATU with about 90 mg-ATU/L which was initially dosed to the system would reach below the inhibition threshold of 1.0 mg-ATU/L after 10 days when 750 mg-COD/L of heterotrophs were present. From the kinetic model, an empirical formula to calculate a safe minimum ATU dose for the batch respirometric test was elaborated. The model also provided a modified experimental procedure to accurately estimate the initial heterotrophic biomass concentration in the sample and its specific decay rate based on IWA Activated Sludge Models. |
