Numerical modeling of nitrogen removal through simultaneous nitritation, anammox and denitrification processes in biofilters

Two process-based models were developed to predict nitrogen removal in biofilters. The first model simulated simultaneous nitritation and anammox (SNA) process in two marble chip biofilters designed to couple nitritation and anammox for nitrogen removal from organic-free, ammonium-rich wastewater. This model was the first attempt to simulate SNA in biofilters. Modeling showed that anammox contributed 34.8% of ammonium removal, supporting the design purpose of enhancing the coexistence of anammox bacteria and aerobic ammonium oxidizing bacteria. In order to achieve total inorganic nitrogen (TIN) removal, simultaneous nitritation, anammox and denitrification (SNAD) was introduced to a marble-slag biofilter for treatment of dairy wastewater. The second model attempted to simulate SNAD. Anammox and denitrification contributed 80.4% and 19.6% of TIN removal, respectively, supporting that the biofilter successfully enhanced TIN removal by employing SNAD. The proposed models are useful tools for evaluating and designing ecological treatment systems.