> > Thanks. So I should look out for a carbon filter purifier. Durham is
> > quite soft, but Leeds (with exactly the same geology) is quite hard
> > (Yorkshire Water artificially harden the water!).
>
> Yeah, now they're privatised they've probably got shares in the
> water softener industry (cynic? me? :)
I think they do it because houses still have lead pipes. The hardened
water furs the lead pipes, preventing dissolution of the lead. Of course,
it furs everything else up - so it is a lot more hassle than its worth.
> I've just cut open a filter, for curiosity's sake, and I'm
> quite surprised - there's not much carbon in there, but a lot of
> what I take to be polymer beads - I guess about 25:75. These
> beads are .5 - 1 mm and white in a used cartridge, so I poked a
> hole in an unused one, and these are yellowy and clear.
> So I take it that this is some sort of osmotic process...
> What I'm wondering now, is if there is any way to rejuvenate the
> used beads, and save having to bulk buy cartridges with monotonous
> regularity. Anyone know how this process works, and if it can be
> reversed to clean the beads?
These sound a bit like ion-exchange resins (can't remember the proper
name), we used them in A-level chemistry. I think the school I was at,
also used them for producing "deionised" water.
There are two varieties. One will swap cations for H+, the other will
swap anions for OH-. No more was explained. It was assumed that exchange
was complete (you usually had to send some "cleaning" water through,
before use - to clean the dregs from the last person!). We used them for
cation counting. Once the cations were exchanged for H+, titration with
an indicator and an alkali would give you the original cation count.
Using both resins, should remove both anions & cations, with the H & OH
combining to produce H2O.
The beads we used were orange. I don't know where you get them from. I
doubt they'll remove many organics.
If I remember correctly, they could be "recharged" by running strong acid
or alkali (respectively) through the beads.
Anyone know anything more about these resins?
Richard