Management of solid wastes is a problem of increasing concern throughout the world. The biodegradable fraction in wastes that cannot be recycled or converted into new products, increasingly is treated through composting. It is the lowest cost alternative to landfilling for many wastes. The number of composting plants operated in the U.S. by industries and municipalities has tripled since 1990. Over 3000 sites are registered today. Backyard composting also is starting to play an important role in the U.S. Industries use composting as a process for the destruction of toxic by-products through a process known as "bioremediation". Finally, the composting process is starting to replace more costly treatment procedures for the destruction and control of human, animal and plant pathogens. Composting, therefore, is becoming a commonly used process.
Various forms of composting have existed since life on earth began. Nature provides an extensive, native population of microorganisms that are generally attached to all organic wastes. When conditions are right, these microbes grow and multiply by decomposing the material to which they are attached (an example is decay of crop residue in soil). From a scientific viewpoint, the composting process is started and managed under controlled environmental conditions rather than accepting the results of natural, uncontrolled, decomposition.
Composting is associated with concepts of reclamation, recycling, treatment and disposal. Reclamation and recycling are parts of the stewardship of saving and reusing natural resources. Treatment and disposal have been a more typical way to cope with wastes for many decades, particularly as a part of the "industrial revolution." Because of concerns for our environment, "disposal" has become a less desirable option.