Industrial composting operations are increasing yearly as communities seek ways to recycle waste materials effectively. Each person in the United States generates 4.5 pounds of waste materials per day, according to a 2008 report by the U.S. Environmental Protection Agency. Even though this is an increase from previous years, the recycling rate has also increased. Industrial-scale recycling rose from 10 percent in 1980 to over 33 percent in 2008.
People in the United States generated 250 million tons of trash in 2008. The U.S. Environmental Protection Agency collects and reports data on the generation and disposal of waste in order to measure the success of recycling programs. During the same calendar year 83 tons of material were composted. Materials are separated before they can be composted.
Organic materials are composted in large scale industrial composting systems. Many cities have waste management programs that separate "green" waste from solid waste. Green waste includes yard clippings, leaves and garbage. "In urban areas, the composting of leaf and tree waste alone can reduce landfill dependency by up to 12 percent," according to an Ohio State University Extension report on integrated solid waste management.
Cornell University Extension defines industrial composting as a manufacturing process, one that takes raw materials and reforms them into a compost product Physical and chemical contaminants are separated from the collected waste materials. Some programs require citizens to separate materials, and some accept a "mixed stream" to the local recycling facility.
Separation techniques include hand separation on conveyor belts, magnetic separation techniques, water or air classification systems and rotating drum methods. Materials are thus separated by weight, size and metal content. A shredding process is then employed to further reduce the particle size of materials.
Methods for large-scale composting include windrows, silos, vertical and horizontal reactors, rotating drums and static piles. Windrow industrial compost systems are regularly turned, elongated piles covered with plastic tunnel-shaped sheeting. They are mechanically turned and monitored for oxygen content and heat. All products are evaluated for potentially toxic chemical content before they are used as organic mulch or compost products.