Kinetics
The conversions within a cycle were investigated in cycle measurements. The measurements were conducted once the system reached a steady functional performance in terms of product spectrum and substrate uptake rates. An overview of all cycle measurements performed is shown in figure 4.
In all systems the majority of the conversions happened in a short period when glucose was present. A process model was made to investigate the stoichiometric and the kinetic characteristics of the conversions observed as described in the material and methods section. An overview of the obtained kinetic parameters and final product spectrum is given in table 2.
The amount of stored polymer produced was estimated using the model. The quantity varied per enrichment but was always significant. At an SRT of 50 d 0.47 gCOD storage polymer was estimated to be produced per gCOD glucose consumed. This amount of storage polymer lowered to 0.43 and 0.32 gCOD·COD-1 respectively at an SRT of 10-20 d and 1-2 d. The maximum specific substrate uptake rate (qSmax) decreased from 0.7 gCOD·gVSS-1·h-1 at 1-2 d SRT to 0.2 gCOD·gVSS-1·h-1 at an SRT of 50 d.