Composting is fine for some leathers but for chrome tanned leathers we really need to persuade the industry to set up facilities to remove chrome first. It is not difficult technically but complex logistically. That way we are left with an organic material which will be good for fertiliser and chromium which can be properly reused in other industries.
If large enough pieces can be obtained then the reuse in some of the new areas where leather is now being used could offer an interesting route, but here the logistics really do look complex.
I would be cautious following this line too rigorously. Materials like zirconium are hardly used. If we can deal better with chromium that is 80% of the issue. We did have excellent historic biotechnology for which leather is famous (and foolishly often ridiculed) using dog and hen dung, urine, cattle blood, the yokes and the white of blood and in most of these cases we now have excellent enzymes and polymers which do the job. More use if enzymes will be very important environmentally. But do not think traditional vegetable tanning a solution to very much. It uses too much material and we do not have enough trees properly managed to tan more than 30% (an estimate but I am confident it is a fair one). Veg tanning effluent creates a huge BOD demand and vegetable leather is not easily biodegradable (that is why so much ancient material can still be found). It does not meet EU standards of biodegrade material. Making vegetable tanned leather still involves lots of inorganic material in the earlier processes and is only suited to some end uses. So I agree with Dr Germann when he looked at all current processing and said for volume production chrome remains the best understood and properly managed the best. My only addition is that before disposal in land fill we should remove the chromium from it. Vegetable tanned leather is unbeatable, but for selected end uses. Leather articles should last a very long time if properly made. My brief case is 30 years old, i still have my father's document folder, over 60 years old and two pairs of Church's shoes, resoled a few times, which are 40 years old. Leather should not be part of fast fashion on a quick journey through use to landfill.
This leads to a page in Russian, but anyway should be aware that I have a degree in leather chemistry, have worked in tanneries around the world for over 40 years using vegetable, chrome, cod oil, zirconium, titanium and all manor of synthetics and my recent paper ob carbon footprinting and CSR in leather is available through these pages. I am a member if the Archaeological Leather Group, and a trustee of both the Museum of Leathercraft and Leather Conservation Centre. I've given a lot of time in 2013 to help re-establish a line of traditional birch bark Russian leather. I love the old leathers but I do not accept they are the only solution for the future. I've studied the damage vegetable tanning did in the Catskills, and the Adirondaks in the 18th and the huge damage done to mangrove swamps in Central America and Asia by tanners. I've spent this morning looking at some less impactful vegetable materials that might be used in the future but to make the 24billion square feet of leather made each year vegetable is not a one hit solution