Respirometric evaluation and modelling of acetate utilization in sequencing batch reactor under pulse and continuous feeding

The study investigated the effect of feeding regime and sludge age on acetate utilization. Parallel sequencing batch reactors (SBRs) were operated at steady-state with pulse and continuous feeding of acetate at sludge ages of 8 and 2days. Acetate was always partially converted to poly-β-hydroxybutyrate (PHB). The adopted model remained equally applicable to oxygen uptake rate and PHB profiles reflecting different feeding regimes and culture history. Sludge age was significant on the rate parameters of storage and direct growth (k _STO, μ _H1), while the feeding regime affected half saturation coefficients (K _STO, K _S1). Changing the sludge age from 8days to 2days reduced the k _STO value from 8.0day ^-1 to 6.5day ^-1 and increased the corresponding μ _H1 value from 1.5day ^-1 to 2.5day ^-1, regardless of the feeding regime; conversely, changing from pulse to continuous feeding reduced K _STO while increasing K _S for the SBR operation at the same sludge age.