Depleted blix with silver removed is about like Miracid. It is actually a strong version of fertilizer for plants that want iron. So, you could in theory, dump it on a bed of azaleas or rhododendrons. I don't advise it, but it can go down most drains if you dilute it. The silver residue is another matter.
If you mix silver depleted blix and color developer, they tend to neutralize each other and dump better.
That is to say that the chemicals tend to cancel each other out in pH and BOD and COD.
PE