3. Results
3.1. Long-term loadings
The calculated long-term biofilter loadings of ammonia, urea, filtered total-N and COD increased with feed loading (Table 1), supported by the measured values obtained in the separate control study. Measured concentrations of TAN were generally higher than the calculated TAN concentrations, while the opposite was observed for urea-N. Measured concentrations of filtered total-N were in good accordance with the calculated filtered total-N concentrations while measured dissolved COD values were higher than those calculated.