Summary for electrocoagulation rinsewater Discussion
Electrocoagulation for pickling rinse water is the focus keyphrase here, and Tim FitzGerald asked whether the process can raise acidic wastewater pH enough to cut caustic use and reach an 8.0-8.1 target. In the answer, the respondent says yes: when properly designed and operated, electrocoagulation will raise pH and can reduce or eliminate caustic demand. The advice is limited, though: it is suitable for rinsewater, but not recommended for concentrated solutions, which the answerer says are better handled with chemicals. The practical takeaway is that electrocoagulation may help save caustic in rinsewater treatment, but it should not be treated as a universal replacement for chemical neutralization in stronger wastes.
Q. I am considering using electrocoagulation to treat my rinse water off the pickling operation I operate. I read in some of the literature that the application of this energy effects pH and will increase my acidic waste water reducing the amount of caustic required to achieve the 8.0-8.1 range I am trying to achieve. Is this true ?
Tim FitzGerald
pickling – Cleveland, Ohio, USA
2003
A. Yes. Properly designed and operated, electrocoagulation will raise the pH and reduce or eliminate the caustic demand. It works for rinsewater but we do not recommend it for concentrated solutions. That’s what chemicals are for.
Paul Morkovsky
– Shiner, Texas, USA
2003
A. Electrocoagulation uses soluble iron or aluminum anodes and electric current to promote dissolving them. There may be some reduction of free acidity to to the direct effect of acid dissolving the anodes, but other than this I don’t think that it will do anything to reduce your caustic use. In fact, if the current dissolves metal at the anode (like it is supposed to do)instead of generating oxygen and hydroxide ions, the reverse situation could occur and the caustic requirement could actually go up a little bit.
Either way, the effect on caustic use will be immeasurably low, and can be calculated by the ampere-hours consumed per liter of solution treated by the EC unit. The calculations are very similar to plating calculations.
Lyle Kirman
consultant – Cleveland Heights, Ohio
2003
? What is the pH of your rinse water?
Sujani Lanka
– Carlstadt, New Jersey
2003