Table 4.

Comparison of actual and default values for the fractions used by the GPS-X model.

Fraction	Definition	Used value	GPS-X Default value
Frsi	Soluble inert fraction of total COD	0.03	0.05
Frslf	VFS fraction of total COD	0	0
Frsf	Fermentable biodegradable fraction of total COD	0.2	0.2
Frxi	Particulate inert fraction of total COD	0.1	0.13
Frxs	No slowly biodegradable substrate	0	0
Insi	N content of soluble inert material	0.05	0.05
Inxi	N content of particulate inert material	0.04	0.05
Frsnh	Ammonium fraction of soluble TKN	0.9	0.9
Ipsi	P content of soluble inert material	0.01	0.01
ipxi	P content of particulate inert material	0.01	0.01
Frss	Readily biodegradable fraction of total COD	0.3	0.2
Frcas	Acetate fraction of total COD	0	0
Frcsol	Colloidal fraction of slowly biodegradable COD	0.13	0.15
SVI	Solid Volume Index	150	159.7

(Source: Authors' work)