Standard Operating Procedure CALCULATION of DOSE RATE FROM

CENTRAL WATER SOP 204

Standard Operating Procedure CALCULATION OF DOSE RATE FROM

JAR TEST

1. 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

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 = 40mg/L x 50L/s

10.1

= 2,000

10.1

= 198mL/min

4.2.2  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

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 Page 3 of 3