Mechanized separation of mixed solid waste and recovery of recyclable products
The method and systems efficiently extract recyclable materials from a mixed solid waste stream. The methods and systems use sizing, density and dimensional separation to produce intermediate waste streams that are enriched in particular recyclable materials. The recyclable materials can then be efficiently sorted from the individual intermediate streams using mechanized sorting equipment.
1. A method for recovering recyclable materials from mixed solid waste stream, comprising:
providing a mixed waste stream comprising comingled dry organic material, wet organic material, and inorganic material;
shredding the mixed waste stream in a shredder and fractionating the shredded mixed waste stream by size to produce first and second sized waste streams;
fractionating the first sized waste stream in a first density separator to produce a light fraction stream and a heavy fraction stream;
fractionating the heavy fraction stream in a second density separator to produce an inorganic stream and a heavy organic stream; and
separately recovering light organics from the light fraction stream and heavy organics from the heavy organic stream.
2. The method of claim 1 , further comprising fractioning the heavy organic stream in a third density separator to produce a wet organic stream and a heavy dry organic stream.
3. The method of claim 1 , wherein the light fraction stream includes paper and plastic and the heavy fraction stream includes wood and textiles.
4. The method of claim 1 , wherein the heavy fraction stream includes wood and textiles and the method further comprises separating the wood and textiles using a 2D-3D sorter.
5. The method of claim 1 , wherein the light fraction stream includes paper and plastics and the paper and plastics are separated using an optical sorter.
6. The method of claim 1 , wherein the first sized waste stream has a lower cutoff size greater than or equal to 2 inches and an upper cutoff less than 16 inches.
7. The method of claim 1 , wherein the first sized waste stream has an upper cutoff size less than 18 inches and a ratio of the upper cutoff to lower cutoff is less than 10:1.
8. The method of claim 1 , wherein the first sized waste stream has an upper cutoff size less than 16 inches and a ratio of the upper cutoff to lower cutoff is less than 6:1.
9. The method of claim 1 , wherein the mixed waste stream includes at least one high value recyclable material selected from the group consisting of paper, plastic, and metal, wherein the mixed waste stream includes at least 20% by weight of a low value material selected from the group consisting of wet organics, green waste, food waste, grit, fines less than 1 inch, asphalt, concrete, textiles, and wood, rubber, film plastic, PVC, foil, rock, used consumer products, low value glass, composite materials, and combinations of these.
10. The method of claim 9 , wherein the waste stream includes at least 50% by weight of the low value material.
11. The method of claim 1 , wherein the waste stream includes at least 10% by weight of wet organic, food waste, and/or green waste.
12. The method of claim 1 , wherein the first sized waste stream is sized larger than the second sized waste stream.
13. The method of claim 12 , wherein the second sized waste stream has an upper cutoff of less than 4 inches.
14. The method of claim 13 , wherein the second sized waste stream has an upper cutoff and a lower cutoff with a ratio less than 10:1.
15. The method of claim 13 , wherein the second sized waste stream has an upper cutoff and a lower cutoff with a ratio less than 6:1.
16. The method of claim 12 , wherein the second sized waste stream has been sized to remove grit.
17. The method of claim 12 , wherein the second sized waste stream is fractionated in a third density separator to produce an organic stream and an inorganic stream.
18. The method of claim 12 , wherein the organic stream from the third density separator is fractionated in a fourth density separator to separate wet organics from dry organics.
19. The method of claim 12 , wherein the wet organic stream includes food waste.
20. The method of claim 19 , further comprising digesting the food waste in an anaerobic digester.