For these types, wastes are composted in a central location. What's Involved Of the types of composting, grasscycling and backyard composting require the least investment by the locality. Systems used to process yard trimmings and other source-separated organics vary in size, price and complexity. The simplest and usually the least expensive is windrow composting. Compostable materials are piled in rows and turned periodically by machine.
Problems associated with windrow composting include leachate production and odor generation.
These may be addressed by moving the operation indoors, but since windrow composting is an area-intensive method, indoor operations may increase the expense considerably. In aerated static pile composting, piles are not turned but instead have air blown or sucked through them. This requires less room than windrow composting, but there can be problems with insufficient temperature on the outside of the pile, as well as odor and leachate problems if performed outdoors. Agitated bed systems are somewhat more expensive in terms of equipment, but require less land. They use bins which are open at the top and generally housed in a building to control odor and the effects of weather.