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Letter 11083
Advice on New Technology that utilizes MgO
to control pH
I am with a company that has developed an innovative technology
that treats acidic wastewater in a flow-through system. We have done
successful testing with wastewater from food processing, chemical
processing, petroleum processing, and steel processing.
I do not want this inquiry to be taken as an ad for this product,
but I have questions about the metal finishing industry.
I have looked at past letters, and back in 1996 there was some
discussion on this page about the use of MgO. Since then there has
been no other discussion that I have found.
This new technology utilizes a reactor column, and a proprietary
MgO, that can be made to control the reaction - with an effluent pH
anywher from the normal 9 assosiated with it, up to 14.
Everyone already knows the safety and environmental benefits of
MgO, but the main problems were the detention time required for
adjustment, and the peak pH of 9. This usually meant that NaOH was
still required at some point.
This proprietary MgO does solve this problem, but requires some
testing at an actuall finishing plant.
I am looking for any advice or comments on the viability of a
technology like this for your industry. Also anything I should
specifically be looking at while testing (or what should be tested
for), and how to start in this industry to gain confidence and
acceptance in the industry.
Any input would be appreciated.
Paul Chapple
- Toronto, Ontario, Canada
I would make a skid mounted prototype of your treatment plant that
would operate at 10 gallons/minute, then find a plating shop who will
let you test it on their wastestream.
We use MgOH in wastewater treatment in batch treatment in its
solid form. I've also played with mixing MgO with water for a
continuous wastewater pretreatment system. For batch treatment MgOH
works well to a pH of 6, but after that the reaction time is quite
slow so we always finish off with NaOH. An oxidizer present in the
acid (or nitric acid itself) will take MgOH back to the oxide and
make some slimey white sludge. For continuous flow treatment, we went
with a continuous mixing and recirculating system that feed as needed
to the waste stream. This used twice as much as in theory, and even
greatly lengthening the reaction time did little to help. (pH range
8.4 to 9.0).
That's all I got to say about that.
Mike Wells
plating works - Jamestown, New York
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