Aerated static piles
The aerated pile process is based on a combination of proven automated turning systems and intermittently aerated static piles. This technology is especially suitable for high throughputs and can be used not only for composting and stabilisation, but also for biological drying. Two different systems can be provided:Shifting pile system
The raw material is piled up in a trapezoidal shape. The automatic turning system (bucket chain conveyor) which provides for transport through the composting hall can be moved in the longitudinal and transverse directions. Depending on the process control and the required degree of decomposition for the mature compost, the material is treated for a period of several weeks. The volume losses which arise during the composting process are compensated by the turning of the material, at which point water may also be added. Shifting pile principle means that all piles will usually be turned once a week.
Freely programmable turning system
This system is able to accelerate the composting process, as it allows control of the process parameters (turning frequency, aeration rate and humidification) and thus the stabilisation of optimum biological conditions. The automatic equipment in the composting hall consists of a belt conveyor with tripper, an overhead bridge and a bucket wheel. Free programming of the turning and discharge intervals allows any chosen retention time to be realised. There is no turning of the pile during the main composting phase; the material is merely aerated (/negative/suction aeration) and, if necessary, irrigated intermittently via the humidifying system mounted on the bridge. Subsequently, the compost material is turned at shorter intervals during a post-composting phase lasting three to five weeks.
It is also possible to use the widely proven technology of intermittent aeration and irrigation of the static pile in projects without automated turning systems. This configuration may be relevant also for lower throughputs, and is suitable for a broad spectrum of feeding, turning and discharge variants using wheel loaders or crane systems. The technology has been in successful use for more than 30 years, as documented by a long list of references. It incorporates proven measuring and control devices and can be designed with the intermittent aeration based on either suction/negative or pressure/positive, or as a combination of both.
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