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Optimal Conductivity for Flocculant Tank ?

To meet a goal of reducing sludge production, I'd like to use as little flocculant as possible. Therefore, I'm interested in controlling the chemical additions to my floc tank by using conductivity as a control parameter. Does anyone have any experience with this type of control scheme and its merits / pitfalls? Or, am I completely off base and I should look at something else? Also, if anyone has tried this, what range does the conductivity measurement typically fall in?

Leo Sharkey
Plating shop employee - Fridley, MN, USA
July 21, 2008

Hi, Leo. Floc and polymer are non-conductive so I think this offers little possibility of success. However, there are optical approaches which might work -- waterproof sender and receiver which, at least in theory, can be placed in the clarifier and report/control based on the transmissivity of the clarified water.

However, the assumption that the amount of polyelectrolyte is controlling how well the floc is settling may not be accurate.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 22, 2008

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July 25, 2008

Leo, yes, you are completely off base if you want to reduce sludge production by reducing flocculant. Flocculant has no impact on sludge generation (in terms of making more or less sludge). The flocculant merely pulls together the solids that are already in the water coming to the flocculant tank. If you want to reduce the amount of sludge generated you need to look at the coagulant that you are adding. If you are using an iron based coagulant, perhaps look at an aluminum based one. Alternatively, try various coagulants or coagulant blends (many times an amine added to a coagulant results in good coagulation with less product).

Gordon

gordon djani
- greenville South Carolina