Composting
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Composting
At a glance |
Composting is a cost effective option for farmers who are producing too much manure and cannot use all the manure nutrients on their land base. New regulations are being implemented that limit the amount of manure nutrients, particularly phosphorus that can be applied to agricultural land. Composting allows manure nutrients to be transformed into marketable products that can be sold off-farm.
Composting is the aerobic decomposition of organic material, which has been used as a waste management strategy for many centuries. The goal of modern composting technology is to create a quality product consistently and cost effectively. The primary economic considerations impacting composting are the capital and operating costs of technology that minimizes the risk of water and air pollution. Economic considerations may also limit the applicability of modern composting technology to processing at least 500 tonnes/year.
Composting can be used instead of or in conjunction with anaerobic digestion. Anaerobic digestion allows some of the potential energy in the manure to be recovered in the form of methane, which can then be used to produce electricity and heat. Following the anaerobic digestion process, most of the manure nutrients still remain and the manure has to be further processed. If the farm land base is large enough, the manure could be spread on the land. However, if the land base is too small to receive all the nutrients generated by farming operations, another solution must be found. One option consists in using a liquid-solid separation process followed by composting to create value-added products that could be sold off-farm. The use of anaerobic digestion alone is not an appropriate solution for farms producing too much manure for their land base.
Another concept involves capturing the potential energy in the manure during the composting process to produce heat. This heat can then be used as a heat source on the farm (i.e., for heating buildings), or it can be used to remove moisture from the composting material. Although capturing heat energy from aerobic composting is potentially feasible, the technology is still not widely used because the cost effectiveness of the process is not guaranteed.
Modified: 03-31-2008
