Denitrification potential and rates of complex carbon source from dairy effluents in activated sludge system

A predictive model for the denitrification performance of complex carbon sources was proposed based on compositional data. Potential and rates of denitrification of single dairy components (lactose, lactate, proteins, fat), as well as binary and complex (modelled "process water") mixtures were assessed using test for nitrogen uptake rate (NUR). In all experiments, denitrification potential of mixtures was found to be significantly higher than the sum of individual potentials and denitrification rate with the readily biodegradable moiety of the mixtures was similar to the highest rate obtained with individual components (lactose or lactate). This work shows that activated sludge acclimated to dairy components can be modelled as a single biomass where the maximal anoxic growth rate of the biomass limits the denitrification rate with dairy components. As a consequence, lactose or lactate determine the maximal denitrification rate possible using dairy effluents.