Most of the stuff on Third World beaches is fairly local in origin. It is the result of just dumping all the trash into rivers or the sewers that also go straight into the ocean. Of course some amount of plastic washes up everywhere. But localized pollution in places like Mumbai is a problem that is only going to be solved with long-term waste disposal solutions. It was not real clear from the story what they intended to do with the waste that they collected, and I hope that it will not end up back on the same beach.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.568.7367&rep=rep1&type=pdf
