Composting

Composting can be done by anyone. A homeowner can use a small composting bin or a hole where kitchen wastes (minus meats and fats) are mixed with grass clippings, small branches, shredded newspapers, or other coarse, organic debris.

Communities may have large composting facilities to which residents bring grass, leaves, and branches to be composted. Such communities often have laws against burning garden waste and use composting as an alternative to disposal in a landfill. Sometimes sewage sludge, the semisolid material from sewage treatment plants, is added. The heat generated in the heap kills any diseasecausing bacteria in the sludge. The materials are usually arranged in long rows, called windrows, which may be covered by roofs. The resulting humus is used to condition soil on golf courses, parks, and other municipal grounds.

The largest scale of composting is done commercially by companies that collect organic materials, including paper, from companies and private citizens. Commercial composting is usually mechanized, using large machines called composters. Raw solid waste is loaded onto a slow-moving belt, then is dumped into a device which turns the waste, and compost comes out the other end within a few days or weeks. This in-vessel or container process allows careful control of moisture and air. Some communities are looking toward such mechanized digesters as a way of helping to solve the municipal solid waste problem as more and more landfills close in the future.