Composting involves the use of naturally occurring aerobic processes which break down organic matter to produce an organic material suitable for use as a soil conditioner and a source of nutrients in agriculture and horticulture.
We operate two In–Vessel Composting Plants at Etwall in Derbyshire and Ufton in Warwickshire, processing approximately 100,000 tonnes of co-mingled green waste per annum. The feedstock for these plants comes from kerbside collections for Warwickshire and East Staffordshire councils. Diverting garden waste away from landfill can help lift local recycling rates, while converting it into compost, soil conditioners and using it to restore landfill sites, naturally benefits the environment.
The In-Vessel Composting process
Our facilities are based around a reception building, feedstock preparation area, a number of concrete composting tunnels, a compost maturation pad and air handling equipment. Incoming wastes are sorted, shredded to achieve a maximum particle size, mixed to achieve the correct "recipe" and then loaded into composting tunnels. Air is drawn through the feedstock with the rate of air flow being controlled to ensure an optimum treatment temperature. Following completion of an initial composting period the material is removed from the tunnel, remixed and returned to another tunnel for the composting process to be completed. The treated material is then stored for a period of 4 to 8 weeks to enable final maturation to occur whereupon the product is screened and sieved to remove any contamination and to achieve a variety of material grades depending on the final end-use.
Other Composting processes
The main difference between composting systems largely relates to scale and whether the process occurs in the open or is enclosed (in-vessel). Most small scale domestic composting systems operate for only short periods at high temperatures and then become cold quite quickly, with the overall process often taking many months to complete. Larger scale systems, where the material is mechanically turned to form a windrow, are more efficient but are only suitable for green waste. They are however used extensively throughout the UK for the treatment of garden waste. In-vessel systems have the advantage of operating at optimal conditions of temperature and moisture content, and because they are enclosed can accept for treatment a wider range of organic materials including food waste. An additional advantage is that air from the composting process, which can be odorous, can be captured and treated.