In terms of water quality, what is better: upstream or downstream chlorination?
Upstream chlorination is preferable, in particular for a reservoir or tank, for 2 reasons:
- You are going to ‘amortize’ chlorine concentration by spreading it throughout a storage volume,
- You’ll be able to protect your tank from bacteriological problems because there will be more chlorine in the system.
I agree with a lot of the suggestions already put forward. It is always more effective to add chlorine upstream in order to take advantage of water contact time. .
However, you should check a few points:
- What is the residence time of the water in the reservoir or tank (for a basic estimate, divide the usable volume by the flow rate to find the average residence time) ) ;
- Be aware of the fact that the average residence time can be very different from the actual residence time because of hydraulic short circuits. ;
- Make sure the operation in question, if it is buried and located under another installation like a filter, has waterproof flaps because chlorine seepage can occur and cause rusting of nearby equipment and risks to personnel.
Let me know if you need any other info.
Totally agree with the arguments in favor of upstream chlorination:
- Maintain a stored volume of chlorine to reduce risk of bacterial contamination
- Meets operational demand for chlorine to limit decrease of chlorine in the network