Systems and methods for processing mixed solid waste
Solid waste that includes a mixture of wet organic material and dry organic material can be are separated using mechanical separation to produce a wet organic stream enriched in wet organics and a dry organic stream enriched in dry organics. The separated wet organic stream and dry organic stream are separately converted to renewable or recyclable products using different conversion techniques particularly suited for the separated wet and dry organic streams.
1. A method for processing mixed solid waste, comprising:
providing a mixed waste stream comprising at least 10 wt % wet organic waste and at least 10 wt % dry organic waste that is comingled;
separating the wet organic waste from the dry organic waste to produce an intermediate wet organic stream and an intermediate dry organic stream, wherein the separation includes,
fractionating the mixed waste stream by size by performing an upper size cut and a lower size cut to produce a sized waste stream, the sized waste stream having a size range where the ratio of an upper cut-off to a lower cut-off is less than 8; and
fractionating the sized waste stream by density;
converting at least a portion of the intermediate wet organic stream to one or more renewable products using at least a first conversion technique; and
converting the intermediate dry organic stream to one or more renewable products using at least a second conversion technique, wherein the second conversion technique is different than the first conversion technique.
2. A method as in claim 1 , wherein less than 40 wt % of the mixed waste stream is separated as a recovered product using manual labor.
3. A method as in claim 1 , wherein less than 1 wt % of the mixed waste stream is separated as a recovered product using manual labor.
4. A method as in claim 1 , wherein the mixed waste stream includes at least 15% dry organic waste and at least 30% wet organic waste.
5. A method as in claim 1 , wherein at least 10 wt % of the mixed waste stream is dry organic waste selected from the group consisting of 3-D plastic, film plastic, paper, cardboard, rubber, textiles, and wood.
6. A method as in claim 1 wherein at least 10 wt % of the mixed waste stream is a wet organic waste selected from the group consisting of food waste, animal waste, and green waste.
7. A method as in claim 1 , wherein separating the wet organic waste from the dry organic waste includes the use of one or more shredders.
8. A method as in claim 7 , wherein the one or more shredders has a throughput of at least 10 metric tons per hour per single line of mixed solid waste.
9. A method as in claim 1 , wherein the first conversion technique is selected from wet digestion, dry digestion, anaerobic digestion or composting.
10. A method as in claim 1 , wherein the intermediate dry stream includes paper and/or plastic and the first conversion technique includes converting the paper and/or plastic to a liquid fuel.
11. A method as in claim 1 , wherein the dry organic material is further dried using waste heat from burning biogas and/or from burning dry organic material prior to being converted by the second conversion technique.
12. A method as in claim 1 , wherein the separation of the wet organic from the dry organic materials yields a dry organic material having less than 25% moisture content and the dry organic material is converted to a refuse derived fuel.
13. A method as in claim 1 , wherein the second conversion technique includes compacting the dry organic material and/or thermally oxidizing the dry organic material to produce electrical power and/or heat.
14. A method as in claim 1 , wherein the mixed waste stream includes at least 20% by weight of low value material selected from the group consisting of wet organics, green waste, food waste, grit, fines less than 1 inch, asphalt, concrete, textiles, wood, rubber, film plastic, PVC, foil, rock, used consumer products, low value glass, composite materials, and combinations of these.
15. A method as in claim 1 , wherein the dry organic waste is enriched in plastics, the second conversion technique comprising sorting the dry organic material by separating 3-dimensional plastics from 2-dimensional plastics to yield a 3-dimensional plastic and converting the 3-dimensional plastic to a plastic product.
16. A method as in claim 15 , wherein the 2-dimensional plastic is converted to a fuel and the 3-dimensional plastic is converted to a recycled plastic product.
17. A method as in claim 1 , wherein the mixed waste stream includes inorganic waste, the method further comprising separating at least a portion of the inorganic waste from the wet organic waste material and the dry organic waste material to form an inorganic waste stream enriched in inorganic waste materials.
18. A method as in claim 1 , wherein the intermediate dry stream includes paper, the method further comprising sorting the paper to produce a paper product.
19. A method as in claim 1 , wherein the intermediate dry stream includes glass, stone, rock, brick, sand, or a combination thereof, the method further comprising sorting the glass and converting it to a construction material.
20. A method as in claim 1 , wherein the intermediate wet stream includes green waste and/or wood, the method further comprising converting the green waste and/or wood into a liquid fuel.
21. A method as in claim 1 , wherein the intermediate wet stream includes green waste and/or wood, the method further comprising converting the green waste and/or wood into a product or fuel pellet.
22. A method as in claim 1 , wherein the intermediate wet stream includes food waste, the method further comprising converting the food waste into a liquid fuel.
23. A method as in claim 1 , wherein the intermediate dry stream includes an organic material selected from plastic, rubber, textile, and mixtures thereof, the method further comprising converting the dry organic material into oil or diesel using a pyrolysis process or a thermal conversion process.