OPTIMIZING NITROGEN REMOVAL REACTOR CONFIGURATIONS BY ON-SITE CALIBRATION OF THE IAWPRC ACTIVATED-SLUDGE MODEL

This paper describes a modified version of the IAWPRC model and the techniques used to calibrate it on site. Growth rate of autotrophic bacteria and the inert wastewater fractions were measured by simple methods, both in laboratory pilots and on full scale. Model predictions were compared to full scale results in large plants (> 100 000 P E). Measured autotrophic growth rates ranged from 0.3 to 0.65 1/d, depending on wastewater toxicity. Most model constants compared well with original IAWPRC proposals, and several wastewater types were identified. Parameters to establish a suspended solids balance are given. Different configurations of plants for nitrogen removal were investigated, including conventional recirculation, sludge reaeration (RDN) and step feed alternate zone denitrification.