For proper chlorination, it is essential to have the required contact time and pay attention to residual chlorine concentration. So I would say it depends on the size of the operation.
Upstream chlorination is preferable, in particular for a reservoir or tank, for 2 reasons:
It all depends on the operation and context; if there is regular overflow then it is to be avoided. However, if the operation is only used for distribution purposes, you should chlorinate upstream with the objective of spreading it throughout the whole system. Every case is different, so choose the method based on all available criteria.
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:
Let me know if you need any other info.
Hello, I’m of quite the opposite view. Upstream chlorination of a reservoir is problematic in terms of residence time, the longer the contact period, the more the chlorine dissipates and you find yourself having to add chlorine to maintain the correct discharge concentration. And this without even going into degassing problems. That is why, it is better to chlorinate downstream and regulate injection of chlorine at discharge via downstream sensors located as far away as possible. At your service.
Hello, this discussion has answers to several different situations and operations. Disinfection is required to meet the goal of potable water from the plant storage area all the way to the point of distribution to the consumer. Operations affected by chlorination: treated wastewater tank (sometimes cleaning), tank liner, pressure tank, water distribution pipes … Alain
If the operation concerns a reservoir, both systems are possible but closely monitor the water residence time in the reservoir and the dose of disinfectant (these two parameters affect the by-products – particularly THMs). Chlorination at output of catchment/treatment plant at base of pump or recirculation tank (upstream or downstream of a reservoir) that can be regulated is an ideal way of distributing chlorine in your network. Adeline.
Totally agree with the arguments in favor of upstream chlorination:
Lots of answers, many of which are contradictory and show how complex our field is. Personally, not to sidestep the question but: it depends on several parameters – the objective (maintaining level of disinfection, one-off disinfecting of pollutants…) of ensuring water quality and in particular the ‘chlorine demand’ – and the downstream context of the operation (distance of nearest water consumers, lag before next chlorination, etc. It is important to know how to meet our goals: safe drinking water and adequate taste, color, odor so that people want to drink it straight from the tap. So before any chlorination is undertaken, it is a good idea to consider the stakes involved.