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-----Wastewater Treatment issue
We use phosphoric acid to remove flash rust of steel parts prior to the barrel zinc phosphate process. We have some difficulty removing the total phosphorous from our discharge into a POTW. Can somone help us on this issue?
Thanks,
Tu Dam- Red Lion, Pennsylvania, USA
2003
Adding Calcium (such as from hydrated lime [affil link] or Calcium Chloride Solution) to your wastewater stream will precipitate most of the Phosphates, thus removing them from your filtered or clarified effluent - but adding Calcium Phosphate to your solid waste stream. The amount required will depend not only upon the pounds per day of phosphate currently going to the Sanitary District, but also on the amounts of other cations which are insoluble with Calcium. The most common of these is sulphate, you might want to consider switching a Sulfuric pickle to Hydrochloric to avoid generating excess sludge.
Craig Haseltine- St Charles, Illinois, USA
2003
Depending on what your doing, how much water you are using, and the parts you are working with, you might find that a closed loop system will give you better control over effluent - essentially by not discharging with exception of batch treatment of regenerants, which gives you complete control over the discharge BEFORE it happens by testing. Also, you could perhaps look at acid recovery for the phosphoric bath, and return the rinses back to the bath for make-up. This eliminates the build up of contaminants and also allows you to close that loop as well. You essentially do not have to dump the bath, which would eliminate a source of phosphorus in your effluent streams.
Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania
2003
You can try the ferric chloride ⇦ on eBay or Amazon [affil link] to precipitate it
Jack, Cui- Singapore
2003
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