[mdeveraux]

I electroplated a small nut as a test, ratio hydrochloric acid / distilled water 1:5, using a 9v battery just until the nut was coated. 
Positive was on the copper, the negative on a bolt, and the nut was moved around with a plastic stirrer. 
I am now uncertain whether the bolt I used for the negative was stainless steel - in hindsight, it could have been.  I've since learned you don't use stainless steel - It's coated in copper now (as is the nut). 
I was going to keep the bath for more copper plating projects, but is it likely to be unsafe now? 
If not, how do I dispose of it?  I heard that using the stainless steel creates toxins/carcinogens so I am worried now.

How can I do this more safely in the future?