Better than biodegradable is to cut consuming by raising cost or thinning the herd. On the consumer side, it is best to reuse rather than discard/recycle. Any disposal system, just like manufacture, usually requires fossil fuels, dedicated acres of land that would have remained wild, and becomes a pollution source to an extent as well.
New materials are a failure because they are a diversion from the only authentic ecologist problem statement. There are too many people and practically any activity we undertake whether primitive or advanced or GreenTM is going to displace wilderness.