Dear All,
            Can Anybody tell me that why if pH decreases, orp & conductivity increases viceversa if pH increases, Orp & conductivity decreases.


Regards,
Jugal N. Rana

Hiya,

Since I might not have time to reply again I thought I'd put my comment in now...


I don't know, but I would guess that, if for example you take and example of nitrification - assume no caustic dosing system:

NH3 solution (reduced = negative ORP) at pH7 >>>> NO3 (oxidised = Positive ORP) + H+ (acid)

Thus, the overall solution becomes more oxidised (more positive ORP), but also more acidic as the process proceeds (lower pH).

However, it's not quite as simple as this, since you can also find that pH and ORP rise together. It can depend on the aeration rate that you have... I can't remember which is which, but for example, with a fast rate aeration ORP can rise as pH falls, and with a slow rate aeration it rises as pH rises!

Don't suppose that helps much does it?  

I wouldn't say I understand it myself fully...

Regards,
argfin