GPS-X Technical Reference

Other Models 296
Terminal velocity reduction factor
The observed settling velocity of the biological granules is found to be less than the
settling velocity estimation procedures. Normally a reduction factor of 0.7-0.8 is
suggested in the literature.
Water content in granule
This parameter defines the water content in a granule and is used to estimate the density
of the granule required in the settling velocity estimation procedure.
Void ratio of stationary granular bed
This parameter defines the void volume in the granular bed under no flow conditions.
Depth of transition zone
The UASB/EGSB model uses a semi-empirical model to decide the solid profile above
the expanded granule bed. In the present model it is assumed that there exists a transition
zone above the sludge bed in which the solid concentration changes from the
concentration in the bed to a fraction of concentration at the end of transition zone. The
depth of this transition zone will affect the solid profile and solid capture efficiency in the
reactor.
Ratio of SS in transition zone to sludge bed
As described above, this parameter represents the ratio of solid concentration at the
transition zone boundary to the solid concentration in the granule bed.
Fraction of non-settleable solids
This parameter signifies the fraction of finer particles in the bed which are non-settleable.
This ratio is expressed with respect to the solid concentration in the reactor.
Solid recovery efficiency of gas solid separator
The solid distribution curve above the granule bed is used to estimate the solids
concentration reaching the gas solid separator at the top UASB/EGSB reactors.
Depending on the efficiency of the gas solid separator the concentration of solids
escaping in effluent is estimated.
GPS-X Technical Reference