Windrow composting has a number of disadvantages. Since it is done in the open air it is significantly affected by the local climate. Often the compost generates odors which may be difficult to control and this may rise complaints from local people. Windrow composting requires large land area and therefore unsuitable for urban.
An alternative method of composting involves mechanical mixing and aeration inside closed digesters. A number of processes are used in mechanical composting and all of them have equipments to control temperature, pH and C : N ratio. The most well known process is the Dano process. This employs drums which are about 30m long and 5 m in diameter. The drums rotate slowly to facilitate mixing and aeration.
The advantages of these mechanical composting are (1) they do not suffer the problems of windrow composting (2) with better control over mixing, aeration and temperature the composting process can be completed in a shorter period than that required for windrow composting.
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