The presence of nutrients stimulated for conditions of active biomass growth alongside PHA storage metabolic activities. PHA production productivity was assessed in terms of the mass of PHA produced in 24 h (ΔPHA24) per initial mass of active biomass introduced into the accumulation process (Xa0). The 24-h active biomass growth response was also assessed as the increase in active biomass (ΔXa24) per initial mass of active biomass (Xa0). Fig. 6 shows the summarized FWP-1 to 4 (Table 2) test outcomes due to increasing levels of N/COD in the feed with constant P/COD of 8 mg/g except for 0 mg/g for starvation conditions. Both active biomass and PHA productivity increased with increased N/COD. The increase was significant with respect to the level of variability observed in replicate control accumulations (FWP-R1 to R4). However, greater levels of active biomass were not produced with N/COD levels greater than about 20 mg/g given also that P was in excess (P/COD = 8 mg/g).