[king12]

I am running an experiment where I am dissolving galvanized steel (zinc and low-carbon steel) by electrolysis.  My electrolyte is tap water with de-icer (composition potassium chloride, sodium chloride, calcium chloride).  After running this for a while, I have a clear solution with orange scum floating and along the sides and bottom of the plastic container.  It has the appearance of dead algae.

Can anyone tell me what this scum is, is it dangerous, and how do I properly dispose of it?  Also what gases are in the bubbles that come from the grounding electrode?

[Extracted]

Is your galvanized electrode dissolving?

[king12]

Yes it is dissolving.  I didn't notice before because I am using a black plastic bin, but there is also a black scum in addition to the orange.

[Extracted]

Black and orange from steel.  Any thoughts?

[Borek]

Iron oxides?

[Arkcon]

Given that oxidation is occurring (by definition of electrolysis), I'm pretty sure rusting of the iron is very likely.  Otherwise, the iron is sitting in water that's rapidly becoming a soup of hydroxides and hypochlorite which will rust it just as well, even if the electrode isn't the one losing electrons.

[king12]

My assumption is that it is iron oxides or iron hydroxides.  These seem to be harmless from what I've read. Can they be dumped in the soil?

I just don't want to assume this if it is actually ferrous chloride or some harmful chemical.