Modeling the Operating Performance of a Drinking Water Biological Aerated Filter and the Formation of Organic Nitrogen

Abstract

In this study, simultaneous storage and growth mechanism, as well as the formation processes of organic nitrogen (ON), were both introduced into activated sludge model 3 (ASM3), and ASM3-ON was formed to predict the operation of biofilm treatment processes and the formation of dissolved organic nitrogen (DON). ASM3-ON was applied to a lab-scale biological aerated filter (BAF) for water supply. During the simulation, the sensitivities of chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), nitrate nitrogen (NO_x^--N), and DON to the stoichiometric and kinetic coefficients in the model were analyzed first by the Sobol method. Then, the model prediction results were compared with experimental values to calibrate ASM3-ON. In the validation process, ASM3-ON was applied to predict the variations of COD, NH₄⁺-N, NO₂^--N, and NO₃^--N in BAF under different aeration ratios (0, 0.5:1, 2:1, and 10:1) and different filtration velocities (0.5, 2, and 4 m/h). The comparison with the experimental results showed that ASM3-ON could accurately predict the variation characteristics of COD, NH₄⁺-N, NO_x^--N, and DON in BAF. This study provided a practical model approach to optimize the operating performance of BAF and reduce the formation of ON through nonexperimental methods.

Keywords: Activated sludge model 3; Aeration ratio; Dissolved organic nitrogen; Filtration velocity; Optimization; Prediction; Soluble microbial products.