I looked it up, the US considers HcL as toxic, the EU only classify it as corrosive. I don't consider it toxic, just extremely corrosive. The main reason I don't consider it toxic is because stomach acid is .5% Hydrochloric by volume. HCL is relativly easy to take care of if spilled it will evaporate, if it manages to get into ground water the only step needed is to neutralize it.
The US CDC site mentions briefly that ingested Hydrogen Peroxide could be toxic, but this is a wording oddity. Hydrogen Peroxide isn't regulated as a toxic substance by the EPA just as an oxidizer.
For the bad parts like the copper metal what is done is the PH is controlled usually via caustic soda and sulfuric acid to a certain range which is different for each metal. At that special PH range the metal tends to precipitate out of the sollution so they add a coagulant (polymer snott really fun stuff to play with) and sometimes aluminium or even ferric chloride to add weight to the precipitate, which goes through several clarifier tanks of various sizes and contructions until you end up with a sludge and treated liquid. The water is tested for purity and discharged to the sewer, the sludge is de-watered in a filter press, then heat dried to remove as much water as possible. That powder is then sent off to a plant that mixes it with concrete to immobilize it into large blocks and tosses it in the ground somewhere. Incineration is the LAST thing you would do to heavy metal bearing waste.