Nitrification process modeling in intermittent sand filter applied for wastewater treatment

The aim of this study was to propose a nitrification process modeling in an intermittent sand filter (ISF) using the biofilm compartment of Aquatic Systems Simulations (AQUASIM) software and the activated sludge model (ASM1) published by Henze et al. (2000). We verified that the software and the initial modeling of equations were suitable for the nitrification modeling until the hydraulic loading rate of 400 L m−2 d−1, organic loading rate of 155.6 gCOD m−2 d−1 and nitrogen loading rate of 20.4 gN-NH4+-N m−2 d−1. In order to adapt the modeling for all hydraulic loading rates (HLR) studied, the set of equations was complemented with the inclusion of an F factor. This factor adapts the ASM1 model to the condition of lesser interaction between influent and the biofilm due to hydraulic loading rate increasing. Thus, the AQUASIM software along with the proposed new modeling was able to simulate the process for all HLR ranging from 100 to 800 L m−2 day−1.