October 25, 2021, 03:42:25 PM
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Topic: Well water contaminants problem - Water purification station  (Read 2191 times)

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Offline end3r

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Hello fellow engineers, I come bearing an interesting question. I'm currently in a trial period at a factory and I seem to have stumbled across an interesting situation.

Lets assume the following system

Well water - MMF(multimedia filter) - Chlorination - Chlorinated water tank - Water softening tanks (strong cationic resin) - 5um Filter - Dechlorination - NaOH addition - Reverse Osmosis Units - CEDI units (Continuous electrodeionization) - Ozonation Tanks -> Ultrapure water.

I had a massive drop in the amount of ozone in water (from 400ppb  to 200ppb).

This isn't the case when the station is running on city water (the ozone generator starts every hour or so in order to keep the ozone levels at the necessary amount).

However when I'm switching to well water it is working full time and in this case not being able to keep the parameter high enough.

In my opinion, given the fact the ozone is a reactive species I'm guessing there is a water contaminant reacting with it leading to the low reading. Something is going through the system and reaches the final point. The water coming out from CEDI is ultrapure - having a conductivity of 1.8 S/m - which means there aren't enough ions in it to react with the ozone. I tested the CEDI outlet for Chlorine, Iron, Manganese, Total Carbon and they're all in the same parameters as before.

Does anyone have a clue what contaminant might be able to pass through the system and have an effect on the ozonation ? Is there something I'm missing here ? I've been thinking lately that it might be CO2, or maybe ammonia or chloramine, but those might be retained by the CEDI.


Offline curiouscat

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Re: Well water contaminants problem - Water purification station
« Reply #1 on: July 28, 2013, 03:32:14 PM »
I'm reminded of a Bottled Water Company, I think it was PepsiCo, in UK that took perfectly drinkable water, ozonized it, and ended up with some nasty chemicals that made the water outside contaminant limits.

I think it was a very similar ozone reaction. Read it up. They won an Ignoble for it too.

Offline end3r

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Re: Well water contaminants problem - Water purification station
« Reply #2 on: July 29, 2013, 12:54:20 AM »
I've read the story, it seems their problem was adding CaCl2 and Bromine for taste and then they ozonized it. Would this be the same case ? I doubt CaCl2 would go past the system, I'm also looking at the bromine part but I think it would be caught by the CEDI system.

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