Muriatic Acid Disposal Problem

A. Carefully neutralize with diluted caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] (sodium hydroxide) to a pH near 7. The final product is sodium chloride and water (very much like sea water). Then investigate if you can dump it in your area.

A. Adding a sodium hydroxide solution to an acid can generate significant heat. It would be safer and cheaper to use Sodium Bicarbonate ([in bulk on eBay or Amazon [affil link] ) in a vessel that is at least twice as large as the volume of liquid that you are neutralizing to allow for bubbling of the Carbon Dioxide gas that will be generated. Add the Sodium Bicarbonate slowly in a well ventilated or outside area. Continue to add the Sodium Bicarbonate slowly until the solution reaches a near neutral pH 6-7. You can then pour it down the drain assuming there is no other contaminants in the muriatic acid (hydrochloric acid). You will have metal contaminants in the muriatic acid if it ever came in contact with metal.

A. Hi.

Guillermo's and Mike's suggestion are both fine for 30 gallons of diluted HCl. But be prepared: the baking soda will bubble more that you think it will even after you've been warned to expect it to bubble a lot. It will take a pretty long time, maybe a couple of hours to do 30 gallons right. After you have double-checked the pH with pH paper ⇦ on eBay or Amazon [affil link] , you can dump it down the drain (assuming that you are not part of a regulated industry).

Neither iron/steel nor aluminum are regulated in most jurisdictions, so if those were the only metals dissolved in it, you're probably still okay. Luck & Regards,


Ted Mooney, P.E. RET
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