In-vessel composting

In-vessel composting generally describes a group of methods that confine the composting materials within a building, container, or vessel. In-vessel composting systems can consist of metal or plastic tanks or concrete bunkers in which air flow and temperature can be controlled, using the principles of a "bioreactor". Generally the air circulation is metered in via buried tubes that allow fresh air to be injected under pressure, with the exhaust being extracted through a biofilter, with temperature and moisture conditions monitored using probes in the mass to allow maintenance of optimum aerobic decomposition conditions. Many In-vessel composters also use augers or rotation to agitate the material, speeding up degradation by continuously homogenizing and mechanically aerating the material. Common examples of this include rotary drum composters from manufacturers like XACT and auger based in-vessel technology like the Earth Flow from Green Mountain Technologies and Biomax G by Sorain Cecchinni.

In-vessel composting is generally used for putrescible municipal scale organic waste processing, including final treatment of sewage biosolids, food waste, or the organic fraction of municipal solid waste. In-vessel composting allows for sanitization of pathogens so the waste can be reclaimed as a soil amendment, while minimizing the environmental impact in the form of odors, runoff or emissions. In-vessel composting can also refer to aerated static pile composting within a building or under removable covers that enclose the piles, as with the system in extensive use by farmer groups in Thailand, supported by the National Science and Technology Development Agency there. In recent years, smaller scale in-vessel composting has been advanced. These often use custom or common roll-off waste dumpsters as the vessel.