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 including household and/or commercial solid waste, the mixed waste comprising at least 10 wt % wet organic waste and at least 10 wt % dry organic waste that is comingled;
comminuting and sizing the mixed waste to produce a sized waste stream with a lower cutoff size greater than 2 inches and an upper cutoff less than 18 inch;
separating the wet organic waste from the dry organic waste in the sized waste stream using at least one mechanical separator to produce an intermediate wet organic stream and an intermediate dry organic stream, wherein the separation has a throughput of at least 10 metric tons per hour of mixed waste;
converting at least a portion of the intermediate wet organic stream to one or more of a renewable fuel products, a soil amendment, a liquid fertilizer, a compost, energy, or a combination thereof using at least a first conversion technique; and
converting the intermediate dry organic stream to one or more of a renewable fuel products, a chemical compound product, energy or a combination thereof 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-dimensional 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, yard waste and green waste.
7. A method as in claim 1 , wherein the mechanical sorter includes a size separator, a density separator or a combination thereof.
8. A method as in claim 1 , wherein the first conversion technique is selected from wet digestion, dry digestion, anaerobic digestion, aerobic digestion or composting.
9. A method as in claim 8 , wherein the first conversion technique produces biogas.
10. A method as in claim 9 , wherein the biogas is converted to a liquid fuel or electricity.
11. A method as in claim 1 , wherein the first conversion technique includes digesting the organic waste in an induced blanket up-flow anaerobic digester.
12. A method as in claim 1 , wherein the dry organic material is further dried using aerobic composting, air drying, solar drying, waste heat from burning biogas and/or from burning dry organic material prior to being converted by the second conversion technique.
13. 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.
14. A method as in claim 1 , wherein the second conversion technique includes compacting dry organic material and/or thermally oxidizing the dry organic material to produce electrical power and/or heat.
15. A method as in claim 1 , wherein the mixed waste stream included 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.
16. 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 recyclable plastic product.
17. A method as in claim 16 , wherein the 2-dimensional plastic is converted to a fuel and the 3-dimensional plastic is recycled to form a plastic product.
18. 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.
19. 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 increase purity of the wet organic and dry organic waste streams; and
recovering at least a portion of the dry organic material as a recyclable product.