CENTRAL WATER
Standard Operating Procedure
1.
SOP 204
CALCULATION OF DOSE RATE FROM
JAR TEST
Purpose
After the completion of a Jar Test, the simulated results of the best dose rates need to be
converted for Plant application. This standard operating procedure provides the necessary
calculations for this to be done. It includes examples of converted Jar Test results into Plant
dosage rates.
2.
Scope
This procedure is applicable to all, but not limited to Water Treatment Plants.
3.
Responsibility
3.1
Operations Manager – shall ensure that staff adheres to this procedure.
Water Quality Team Member – is responsible for the accuracy of the calculations performed.
4.
Procedure
4.1
Preliminaries


Determine optimum dose rates from observations made during Jar Test procedure.
Ensure these results have been recorded on Form 002 – Coagulant Jar Test Log Sheet.
Conversion Calculations
To convert:
L/s to ML/day – Multiply by 0.0864
Example:
100 L/s to ML/day
=
100 x 0.0864
=
8.6 ML/day
ML/day to L/s – Multiply by 11.57
Example:
10 M/L/day to L/s
=
10 x 11.57
=
115.7 L/s
CALCULATION OF DOSE RATE FROM JAR TEST – SOP 204
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4.2
Activity
Chemical Feed Calculations
4.2.1
Alum Dosing
To determine the required Alum dosage rate, a Jar Test must have been performed. To convert
the required Jar Test dose rate to plant application, use the following calculation:
Alum Pump Capacity Required = Alum Dose (mg/L) x Plant Flow (L/s)
10.1
Example:


Jar Test = 40mg/L
Plant Flow Rate = 50L/s
Alum Pump Capacity Required
=
=
=
4.2.2
40mg/L x 50L/s
10.1
2,000
10.1
198mL/min
Lime Dosing
To determine the required Lime dosage rate, a Jar Test must have been performed. To convert
the required Jar Test dose rate to plant application, use the following calculation:
Lime Capacity Required
= Lime Dose (mg/L) x Plant Flow (ML/day)
1440 (Minutes / per day)
= g/min
4.2.3
Polyelectrolyte Dosing
To determine the required Poly dosage rate, a Jar Test must have been performed. Poly solution
strengths can vary from plant to plant, but are generally between 0.1% and 0.5%.
To convert the required Jar Test dose rate to plant application, use the following calculation:
Poly Pump Capacity Required = Poly Dose (mg/L) x (Plant Flow (L/s) x 60 seconds)
Poly Concentration (1.0g/L – 5.0g/L)
Example:
For a Water Treatment Plant using a poly solution strength of 0.25%.
0.25% Poly Solutions Strength = 2.5g/L
CALCULATION OF DOSE RATE FROM JAR TEST – SOP 204
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Jar Test = 0.2mg/L
Plant Flow Rate = 50L/s
Poly Pump Capacity Required = 0.2mg/L x (50L/s x 60 seconds)
2.5g/L
= 600
2.5
= 240ml/min
CALCULATION OF DOSE RATE FROM JAR TEST – SOP 204
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