plating, anodizing, & finishing Q&As since 1989
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.
Falls Township, Pennsylvania
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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