Composting is a form of recycling that mimics
nature’s recycling of nutrients—one of the four
scientific principles of sustainability. It involves
allowing decomposer bacteria to recycle yard trimmings,
food scraps, and other biodegradable organic
wastes. The resulting organic material can be added
to soil to supply plant nutrients, slow soil erosion, retain
water, and improve crop yields. Homeowners can
One way to recycle is to send mixed urban wastes to
centralized materials-recovery facilities (MRFs or “murfs”).
There, machines or workers separate the mixed waste
to recover valuable materials for sale to manufacturers
as raw materials. The remaining paper, plastics,
and other combustible wastes are recycled or burned to
produce steam or electricity to run the recovery plant
or to sell to nearby industries or homes.