GPS-X Technical Reference

105 Suspended Growth Models
Standard Oxygen Transfer Efficiency (SOTE)
The user has the option of using a constant SOTE or using a correlation in GPS-X to
calculate the SOTE. When using the constant SOTE option, the default value (0.3)
represents a typical estimate of the efficiency for fine bubble diffusers submerged at
4.3 m (14 ft.).
Alternatively, GPS-X has SOTE correlations for fine bubble, coarse bubble, and jet
diffusers. For fine bubble aeration, the SOTE correlations are based on a regression
equation developed by Hur (1994) which is shown below:
Equation 6.25
where:
AF = air flow per diffuser (scfm per diffuser)
d = diffuser submergence (ft.)
DD = diffuser density (diffusers/100ft 2 )
A 1, A 2, A 3, A 4, and A 5 = regression parameters
As shown, this equation depends on the depth of submergence of the diffusers, the
diffuser density, and the airflow per diffuser. Using this equation and the data found in
Hur (1994), Hydromantis re-estimated the regression parameters to improve the fit of the
regression. Separate regressions were performed for ceramic disc, ceramic dome,
membrane disc, and membrane tube diffusers. The values of the regression coefficients
can be found in the System > Input Parameters > Physical > More form.
There is also an option to use a user-defined SOTE correlation. The correlation has the
same form as Equation 6.25. The adjustable regression coefficients are found in the
System > Input Parameters > Operational > More form of most biological objects.
A separate correlation for coarse bubble and jet diffusers has been developed by
Hydromantis based on data found in Mueller et al (2002) as shown in Equation 6.26.
Coarse Bubble and Jet SOTE
Equation 6.26
GPS-X Technical Reference