Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Selective removal of Calcium from wastewater
2003
Q. From our waste water we want to concentrate our zinc level by means of electrodialysis or reverse osmosis. We want to achieve a zinc concentration 80 times as high as the starting level. The problem is that there is too much Ca in our wastewater (240 mg/L) and it will precipitate as CaSO4. Does anyone know of a possibility to remove the calcium and not the zinc?
Koen Joris- Belgium
A. I'll offer 2 suggestions:
1) If the source of the Ca is hard water used for rinsing, switch to using de-ionized water for your zinc drag-out rinse, or
2) Use a heavy metal selective (chelating) ion exchange resin to extract the Zn but not the Ca.
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2003
Q. CaSO4 precipitated in outlet of pipe and we could not pass rinse water to our ETP plant because pipeline choked. Give me advice for that?
yogini kalambhe- Nagpur, Maharashtra, India
December 16, 2016
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