Many people think of composting organic matter as a way of keeping solid waste out of landfills, but a new study from North Carolina State University finds there can be significant environmental benefits associated with using compost at landfills. “There are an increasing number of composting programs out there, and many of them are required to use the resulting compost ‘beneficially,’” says James Levis, corresponding author of the study and a research assistant professor of civil, construction and environmental engineering at NC State. “A lot of state and local regulations don’t recognize alternative daily cover as a beneficial use. But our work shows that using compost as alternative daily cover at landfills is competitive, and often superior, to the use of compost as a soil amendment in terms of its environmental benefits.”
Meanwhile, while most of the nation’s yard waste is already turned into compost, a small and rapidly growing percentage of its food waste is also being composted. However, compost from food waste often contains broken glass and other contaminants, making it unsuitable for many soil amendment uses such as in gardens or agricultural fields. There are technologies available to remove contaminants, but these increase the cost of composting. In addition, there is not always a sufficient local market for all of the available compost.
Specifically, the model looked at five environmental impacts:
- Global warming potential, or the cumulative warming effect of any greenhouse gases released by the two cases.
- Acidification, or the extent to which each case contributes to acidification of the hydrological system (e.g., acid rain).
- Eutrophication, or the amount of nutrients released to ground and surface water by each case.
- Cumulative energy demand, or the amount of fossil fuel resources needed for each case, as well as the amount of fossil fuel use that each case offsets.
- Abiotic resource depletion potential, or the amount of any non-biological, non-renewable resource (e.g., phosphorus) needed to perform each case, as well as the amount of those resources that each case offsets (e.g., the phosphorus in compost used to amend soil in gardens and croplands reduces the need for mined phosphorus in fertilizers).
- The researchers ran a range of simulations in order to account for both uncertainty and the variety of different circumstances under which the two cases might take place.
Source: Waste Today Magazine
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