CENTRAL WATER
Standard Operating Procedure
SOP 208
AMMONIA DOSE CALCULATION
1. Purpose
This standard operating procedure describes the process of calculating Ammonia dosage per day to
maintain a ratio in the range of 3.1 - 3.9 parts chlorine to 1 part Ammonia required for
Chlorammination.
2. Scope
This procedure is applicable to Central Water Treatment Plant and Water Quality Team personnel.
3. Responsibility
3.1
Operations Manager – shall ensure that staff adheres to this procedure.
3.2
Water Quality Team Member – shall:
•
Calculate and adjust the ammonia dose rate at the Central Water Treatment Plant in
accordance with this procedure.
AMMONIA DOSE CALCULATION – SOP 208
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4. Procedure
4.1
Flow Chart
AMMONIA DOSE CALCULATION – SOP 208
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4.2
Preliminaries
4.2.1 Obtain amount in Kg of chlorine used in preceding 24 hours (set points log sheet)
4.2.2 If unfamiliar with pump time down procedure, print off OM 003 – Time Down of Metering
Pump
4.2.3 Calculate the dose rate of chlorine over the last 24 hour period by using the following formula:
•
4.3
Chlorine used per day Kg ÷ plant ML per day = Chlorine mg/L
Activity
4.3.1 Perform time down of ammonia dosing pump
4.4
Calculation
*Ammonia is 25% of Available Ammonia
4.4.1 One increment on Ammonia site tupe = 0.05ml
4.2.2 Formula to obtain Ammonia mg/L:
(0.05 / time to drop increment) x 60 x 60 x plant run time = Litres per day
(Divide by 4 for 25% available ammonia) Litres per day divided by 4 = Kg/per day
Kg/per day divided by plant volume (ML / per day) mg/L
4.4.3 Formula to obtain Chlorammination ratio:
(Chlorine mg/L) / (Ammonia mg/L) = Chlorammination ratio
4.5
Action
4.5.1 If formula outcome is within Chlorammination ratio (eg. Between 3.1:1 and 3.9:1) the ammonia
pump dose rate does not need to be changed.
4.5.2 If formula outcome is not within Chlorammination ratio (eg. outside 3.1:1 and 3.9:1) the
ammonia pump dose rate will need to be altered (+ or -) and steps 4.3 to 4.4.1 will need to be
repeated until Chlorammination ratio is within target range.
5.0
Documentation
Nil
6.0
Definitions and Acronyms
AMMONIA DOSE CALCULATION – SOP 208
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6.1
Chloramination – The mixture of chlorine and ammonia to stabilise chlorine residual
7.0
References
7.1
MSDS’s (Material Safety Data Sheets)
7.2
OM 003 – Time Down of Metering Pump
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