Simulation of dissolved oxygen-and ammonia-based aeration control strategies in a mainstream deammonification biofilm process

We report on the development and evaluation of a biofilm model implemented in the SIMBA# platform to simulate a bench-scale deammonification sequencing batch moving bed biofilm reactor (SBBR) fed with pretreated primary effluent. The model predicts selective ammonia oxidizing organism (AOO) anammox (AMO) enrichment under sidestream loading, and then uses the sidestream enriched deammonification biofilm as the initial state to simulate SBBR operation under mainstream loading. The model effectively simulates the ammonia removal dynamics of the experimental SBBR. Adjustment of biofilm erosion parameters allowed prediction of highly efficient AMO and biofilm thickness retention in accordance with experimental observations. The model predicts high sensitivity to dissolved oxygen concentration, wherein efficient nitrogen removal is achievable at oxygen concentrations as high as 0.5 mg/L, but nitrite oxidation overtakes anammox at DO concentrations equal to 1 mg/L.