GPS-X Technical Reference

95 Suspended Growth Models
where:
V = reactor volume (m 3 )
C L
Q
C in
K La
C * ∞
r
= concentration of dissolved oxygen (DO) in the reactor (mg/L)
= influent flow rate (m 3 /d)
= concentration of DO entering reactor (mg/L)
= oxygen mass transfer coefficient at field conditions (1/day)
= DO saturation concentration at field conditions (mg/L)
= rate of use of DO by biomass (g/day), the respiration rate
The volume flows, and reaction rates are known from specifications or other modelling
equations leaving two terms that must be calculated in order to solve the dissolved
oxygen mass balance over time for the DO concentration in the reactor, C L:
1. DO saturation concentration at field conditions, C * ∞, and,
2. Oxygen mass transfer coefficient at field conditions, K La
Calculation of DO Saturation Concentration at Field Conditions
The DO saturation concentration at field conditions is calculated as follows:
Equation 6.2
where:
τ
β
Ω
C * ∞20
= temperature correction factor (unitless)
= correction factor for salts, particulates, and surface-active substances
(unitless)
= pressure correction factor (unitless)
= DO saturation concentration at 20°C and 1 atm (mg/L)
GPS-X Technical Reference