Recycled filament is often just as expensive as new filament.
If you’re worried about the environment, why don’t you just use PLA as filament.
PLA is basically a environmentally friendly and renewable type of filament. Not only that, it is a very hard material as 3D filaments go and has a tensile strenght that is easily twice that of ABS. Downside is, it has no basically NO flex at all, which means parts in PLA don’t really bend but just break. And of course, PLA has a low operating temperature range of only 50-55 degrees Celsius.
Nevertheless, if you print two parts of the same dimensions and start putting a load on it, PLA will usually support almost twice the weight that ABS will.
If you need a material that will stand up to more heat, you might want to try the new Colorfabb HT filament. That doesn’t have the fumes, odor, shrinking and warping that ABS has, has a higher tensile strenght, similar impact strength and similar temperature range. The Formfutura Apollo-X filament might also be a good choice.
Basically, I think that for many if not most parts, there are better alternatives to ABS. It has become my least favorite material to use. For most uses I can use PLA, PETG or one of the already mentioned new filaments which give less printing problems and perform better in almost every circumstance.