Composting is a system of waste treatment that involves engineered biological decomposition of solid biodegradable residues under controlled conditions. Although material like paper can be put in composters, the ideal material for composting is waste food and plants. Paper may not decay fast enough. Natural micoroganisms break down the waste material so that after a period of time - several months to severl years - the waste is no longer recognizable as the material it started from. The processed waste is called "compost" and can be used as a soil adjuvant.
Composting efficiency is enhanced when the material is porous enough to allow free flow of liquid water, air, and microorganisms. Studies have shown that smaller particle size results in faster and more efficient composting. Operators of composters often add bulking material such as sawdust and straw. When one batch of waste is finished composting, some of it is added to a fresh batch to act as an inoculum.
While many households engage in composting on a small scale, large composting operations run all over the country, especially where agriculture is important. Many will take waste from businesses. Some operations are commercial and some municipalities have compost collection systems.
Another benefit of composting is that it can be done near where the waste is generated, and can be done on a small scale. However, there are advantages to very large composting operations as the heat the pile generates and environment it provides for bacteria and worms make the waste degrade more rapidly.
Composting works best when the waste material is not too far removed from nature. Yard waste is ideal, as composting is just a managed way of facilitating what would happen in nature. Most yard waste is cellulose and hemicellulose. Paper, which is also cellulose and derived from wood, can decompose through natural processes, but it is slower. For that reason paper is usually excluded from compost bins, although incidental paper is not a worry.