Modeling of Nitrification Under SubstrateInhibiting Conditions
by Chai Sung Gee, (Res. Assoc., Illinois State Water Survey, 2204 Griffith Dr., Champaign, IL), Makram T. Suidan, M.ASCE, (Prof., Dept. of Civ. Engrg., Univ. of Illinois at UrbanaChampaign, 3230 Newmark Civ. Engrg. Lab., 205 N. Mathews Ave., Urbana, IL 618012397), and John T. Pfeffer, M.ASCE, (Prof., Dept. of Civ. Engrg., Univ. of Illinois at UrbanaChampaign, 3230 Newmark Civ. Engrg. Lab., 205 N. Mathews Ave., Urbana, IL)
Journal of Environmental Engineering, Vol. 116, No. 1, January/February 1990, pp. 1831, (doi: http://dx.doi.org/10.1061/(ASCE)07339372(1990)116:1(18))
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Journal Paper 
Abstract: 
A mathematical model was developed for the biologicalnitrification process. The model assumed two consecutive oxidation steps occurring under a substrateinhibiting condition. The mathematical model was calibrated using data obtained from batch experiments performed on the contents of five chemostats operated to steadystate on a feed containing 1,000 mg/L of ammonianitrogen. In the batch experiments, initial ammonia concentrations ranging from 100 to 1,000 mgN/L were used. Timevarying concentrations of ammonia and nitrite were collected until the oxidation of these constituents was complete. Parameter sets that optimized the fit on the mathematical model to the experimental data were obtained by nonlinearregression analyses. The oxidation of ammonia to nitrite was well represented by the Haldaneinhibition model. The Haldaneinhibition model did not satisfactorily describe the oxidation of nitrite to nitrate. It was observed that the simultaneous presence of both nitrite and ammonia led to the inhibition of nitrite oxidation. Modification of the model to consider a revised inhibition mechanism that accounted for the observed behavior was quite successful for the interpretation of the nitriteoxidation data. 
