I would imagine there are ethical and municipal legal issues around disposal of old shocks and strut assemblies. I have recently replaced the both and am wondering if anyone can share what they did to dispose of their old components.
With my springs and struts I recycled them. The springs are all metal, my town recycles metal so no issue there. My old struts, I opened them up (I don't remember if I beat them apart or if the dis-assembled), removed the oil and all non-metal parts, and then I recycled the remaining metal parts as well. I captured the oil and recycled that with my motor oil. I remember that it took roughly 5-10 minutes to pull each strut apart. Hope this helps, Russ.
For the struts and shocks, I wear safety gogles and drill (or punch with an air chisel) two holes , one at each end. Then push them up and down over my oil change pan until all the oil is out. When completely empty, they 'clang' when moved up and down -- there is zero resistance to movement. In that state, my local metal recycler will take them.
One must wear safety glasses when working with pressurized struts because when you poke the first hole, very small metal chips often come flying out at high speed. It is surprising how fast and forcefully the stuff flies out and it definitely can lodge some metal into your eye, so be careful.