Hanna Instruments HI 98186 - Manual (Page 24)

24
SOUR MEASUREMENT SOUR MEASUREMENT SOUR MEASUREMENT SOUR MEASUREMENT SOUR MEASUREMENT
The Specific Oxygen Uptake Rate (SOUR), also known as the oxygen con-
sumption or respiration rate, is defined as the milligram of oxygen consumed
per gram of volatile suspended solids (VSS) per hour. This quick test has
many advantages: rapid measure of influent organic load and biodegrad-
ability, indication of the presence of toxic or inhibitory wastes, degree of
stability and condition of a sample, and calculation of oxygen demand rates
at various points in the aeration basin.
The following equation is used for SOUR determination:
SOUR = OUR / Solids Weight
where:
OUR is the Oxygen Uptake Rate (see equation on pag 20)
Solids Weight is the
Total solids or the Volatile suspended solids weight in
g/L
Temperature correction:
The SOUR value is corrected to 20 °C (68 °F) according to the Farrel
and Bhide equation:
SOUR
20
=SOUR
T
x
Q
(20-T)
Where T is the measured temperature in °C and
Q
is a temperature
dependent variable:
Q
= 1.05 for T above 20 °C
Q
= 1.07 for T below 20 °C
This calculation is valid only for temperature values in the range 10 to 30 °C.
Temperature correction is performed only if the option SOUR @20°C is
enabled from SOUR configuration in the setup menu.
Before starting a SOUR test remember to set the SOUR configuration from
the setup menu.
SOUR measure screen:
If the SOUR value is corrected to 20 °C (68 °F) the message “@20°C”, or
”@68°F” according to the currently selected temperature unit, will be
displayed above the measured temperature.
Press Start to begin a new SOUR test.