some plastic can be reused by grinding it down to granule minerals.Waste management. There should be govt run waste management for industrial, commercial and residential site, especially for slums. Its really low cost in India with your huge amount of labour.
Also public bins and plentiful public cleaners. People tend not to make a mess somewhere already clean.
Another thing to consider is fines for those who litter. Hire people wearing body cams and pay them to patrol the streets in busy areas fining anyone who drops litter.