MIOX RIO Series Operators Manual
P/N: 102-00076-G Page 70
Oxidant Demand Testing
The oxidant demand of water is a measure of the amount of oxidant needed to properly
disinfect water. This value is extremely important for accurately sizing and maintaining
MIOX equipment. Oxidant demand is determined by adding oxidants in several
concentrations to raw untreated (sample) water and measuring the FAC over time.
Equipment Needed
100 mL graduated cylinder
Four (4) 100 mL glass jars with lids
Pipette that can accurately measure 0.1 mL increments
Chlorine test like (i.e. DPD, Color Wheel, Colorimeter, or AccuVac)
Timer or watch
Calculator
Identify Starting Range
The initial oxidant demand test should use a 5 ppm dose to identify the correct starting
range. If a 5 ppm dose is consumed in less than 30 minutes, the demand of the water is
greater than 5 ppm, and the dose rates of 10, 15, and 20 ppm should be used for testing.
Conversely, if the 5 ppm dose is only moderately decreased in 30 minutes testing should be
performed with 1, 3, and 5 ppm doses.
Use the following formulas to determine the amount of oxidant and sample water to use
(based on 100 mL samples).
Dilution Factor (X) = Oxidant FAC / Dose
mL of oxidant = 100 / X
mL of sample water = 100 - (100 / X)
Oxidant FAC is the concentration of oxidant, which varies with each MIOX OSG model. The
output of each unit should be measured, according to the procedure for Chlorine Testing, to
determine the exact concentration of the oxidant and catholyte.
Example:
1. Determine the amount of oxidant and sample water to be used. Always start with start
with a 5 ppm dose for the first test. Suppose you are using a MIOX OSG that just
generated an oxidant solution concentration of 250 ppm. First, you must determine the
dilution factor (X):
Dilution Factor (X) = Oxidant FAC / Dose = 250 / 5 = 50
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