Effects of different hydraulic models on predicting longitudinal profiles of reactive pollutants in activated sludge reactors

Abstract

This paper presents effects of dispersion on predicting longitudinal ammonia concentration profiles in activated sludge bioreactor located at "Wschod" WWTP in Gdansk. The aim of this study was to use the one-dimensional advection-dispersion Equation (ADE) to simulate the flow conditions (based on the inert tracer concentrations in selected points) and longitudinal profile of reactive pollutant (based on the ammonia concentration profiles in selected points). The simulation results were compared with the predictions obtained using a traditional "tanks-in-series" (TIS) approach, commonly used in designing biological reactors. The use of dispersion coefficient calculated from an empirical formula resulted in substantial differences in the tracer concentration distributions in two sampling points in the bioreactor. Simulations using the one-dimensional ADE and TIS model, with the nitrification rate incorporated as the source term, revealed that the hydraulic model plays a minor role compared to the biochemical transformations in predicting the longitudinal ammonia concentration profiles.

Mathematical Modelling and Computer Simulation of Activated Sludge Systems

“…For example, at the Rock Creek WWTP, Hillsboro (USA), the best accuracy in comparison to the results of three tracer studies (measured E L =1040-1580 m 2 /h) was obtained for the formula of Fujie et al (1983) (calculated E L =990-1020 m 2 /h). With the same formula, Zima et al (2008) calculated E L = 853 m 2 /h for a tracer test at the Wschod WWTP (Poland), but that value was approximately 40% lower compared to the numerically optimized coefficient (similar to one test at the Rock Creek WWTP). With the same formula, Zima et al (2008) calculated E L = 853 m 2 /h for a tracer test at the Wschod WWTP (Poland), but that value was approximately 40% lower compared to the numerically optimized coefficient (similar to one test at the Rock Creek WWTP).…”

“…When the calculated E L coefficients were applied to the 1-D ADE, the average relative deviations (ARD) were higher by only less than 2.1% from the ARD corresponding to the optimum value of E L (Makinia and Wells 2005). Iida (1988), Makinia and Wells (2005), and Zima et al (2008). Iida (1988), Makinia and Wells (2005), and Zima et al (2008).…”

Combining Computational Fluid Dynamics (CFD) with a Biokinetic Model for Predicting Ammonia and Phosphate Behavior in Aeration Tanks

“…During the initial simulations with the set of model parameters from Zima et al (2008), the predicted NH 4 -N concentrations in the compartment outlets accurately matched the data points except for the effluent from the first compartment (x = 42 m). In that point, the predicted value was higher by over 1 g N/m 3 in comparison with the measured value.…”

“…The best approximations (= 993-1016 m 2 /h) were generated by the formula of Fujie et al (1983). With this formula, Zima et al (2008) calculated E L = 853 m 2 /h for the first trial operating conditions (July 2005) at the "Wschod" WWTP.…”

Quality assurance/quality control in wastewater sampling

“…However, if two trunk sewers are combined at the influent of a STP, the mixing of dissolved compounds also depends on the geometry and hydraulics of the confluent (mixing length; Figure 7.5). In larger structures within STPs (e.g., primary clarifier or activated sludge tanks), or in wetlands, mixing of the influent, short cut flows or dead volumes must be considered for a proper assessment [25][26][27][28][29][30][31][32][33][34].…”