Cardboard: composting

The composition of MSW varies significantly from city to city. The compostable waste fraction represents typically more than 25% in most of the Asian cities, followed by non-compostable waste, paper and cardboard, and plastics, as shown in Figure 4. 

All compost heaps need a mix of greens —soft green matter high in nitrogen—and browns — tougher plants that take longer to rot and are high in carbon. If you put in a lot of kitchen waste, add bulkier items such as cardboard and egg cartons. 

With the slower, cooler method, start off the composter with a 12 in (30 cm) layer of mixed matter and add to it when you can. Don t put in too much of one thing kitchen scraps should be mixed with bulkier pieces of cardboard or scrunched-up paper, and grass clippings with coarser bits of plants. If the heap becomes too wet, fork in some bulky woody matter or cardboard. A handful of ground agricultural limestone stops the heap from becoming acidic, which slows down decomposition. Check the bottom section of the heap after several months and any dark, well-rotted matter can be dug out ready for use. Then mix up the remaining material, water if necessary, and return it to the composter. 

Plastics can be discarded and sent to local landfills for disposal. In 2010, the United States collected over 250 miUion tons MSW. In 2010,34.1% or 85 million tons of solid waste was recycled or composted. Residential waste comprises approximately 64% of the MSW and commercial waste comprises 35% of the waste. Table 6.3 lists the materials collected at a typical landfill in the United States in 2010. Organics are the largest component of the waste stream sent to landfills. Paper and cardboard account for 29%, food and yard trimmings account for 27%, plastics comprise 12%, metals are at 9%, rubber and textiles are at 8%, wood at 6%, glass at 5% miscellaneous at 3% (EPA Municipal 2010). 

Paper is broken up into small pieces and re-formed to make new sheets of paper. This takes less energy to do than making paper from trees. However, paper can only be recycled a few times before its fibres become too short to be useful, and the recycled paper is often only good enough for toilet paper or cardboard. But it can be used as a fuel or compost instead. 

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