Chlorine Dosage Calculation

Chlorine is widely used in the treatment of water to kill bacteria and other harmful microorganisms. To determine the correct dosage of chlorine to be used, the following factors must be considered:

- Water flow rate
- Volume of water to be treated
- Desired residual chlorine level
- Contact time

Given the following parameters:

- Water flow rate: 20,000 cubic meters per day
- Chlorine usage: 8 kg/day
- Residual chlorine level: 0.2 mg/litre
- Contact time: 10 minutes

We can calculate the chlorine dosage using the following formula:

Dosage = (Chlorine Usage / Water Volume) x Contact Time x 1000

Where:

- Dosage is the amount of chlorine needed in mg/litre
- Chlorine Usage is the amount of chlorine used in kg/day
- Water Volume is the volume of water treated in litres
- Contact Time is the time in minutes that the chlorine is in contact with the water
- 1000 is a conversion factor from kg to mg

Calculation:

Water Volume = Flow Rate x Time
Water Volume = 20,000 m3/day x 1000 L/m3 x 10 min / 1440 min/day
Water Volume = 138,889 L

Dosage = (8 kg/day / 138,889 L) x 10 min x 1000
Dosage = 0.0576 mg/L or 57.6 ppm

Conclusion:

To achieve a residual chlorine level of 0.2 mg/litre after a 10-minute contact time, a dosage of 57.6 ppm of chlorine is required. It is important to note that the dosage may vary depending on the water quality and the desired residual chlorine level. Therefore, regular monitoring and adjustment of the dosage may be necessary to ensure effective disinfection.