As with all raw materials there is a proportion of these nets that isn’t reusable, either because it is biology (seaweed, worm casts and the like) or because it has different physical properties to the rest of the material.
In two of these cases, nets one and two, the main contaminant is a white braided cord.
I’ve come up with a means to separate most of it and have produced what miners would call ‘a concentrate’ which has a high proportion of useable nylon in a form that is managable. Its not 100% efficient, but then what processing technology is ?
Below are the three products for nets one and two, with close-ups of the concentrate and the waste.