A hybrid model which incorporated a biofilm model into the general dynamic model was developed to predict the effluent quality of a combined activated sludge and biofilm process-Taiwan National Central University Process 1. The system was performed under three different dissolved oxygen (DO) conditions in the oxic tank, including 2.0, 1.0, and 0.5 mg/L. When the DO increased from 0.5 to 2.0 mg/L, the soluble biodegradable substrate (SS) and soluble phosphate (P O4) in the effluent were not significantly influenced. Their removal efficiencies were above 92 and 94%. Ammonia-nitrogen (N H3) removal efficiency increased from 36 to 83% and nitrate-nitrogen (NO3) increased from 1.7 to 2.9 mg/L. In biofilm, when the DO was 2.0 mg/L, the active autotrophic biomass (Z A) fraction was 15.7% (surface) to 12.9% (substratum). But when the DO was 0.5 mg/L, the ZA fraction became lower and the fraction was 6.2% (surface) to 3.5% (substratum). The fraction of active nonpoly-P heterotrophic biomass (ZH) in the biofilm did not vary significantly, the values were about 28-35%. ZI decreased as the DO increased. SS in the biofilm did not vary significantly and was maintained at about 2.0 mg/L. When DO increased, NO3 also increased, NH3 decreased from 13.1 to 1.8 mg/L in biofilm.
|Number of pages||9|
|Journal||Journal of Environmental Engineering|
|State||Published - Dec 2004|