Environmental impact of two aerobic composting technologies using life cycle assessment |
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Authors: | Erasmo Cadena Joan Colón Adriana Artola Antoni Sánchez Xavier Font |
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Institution: | (1) Composting Research Group, Department of Chemical Engineering, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain |
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Abstract: | Background, aim, and scope Composting is a viable technology to treat the organic fraction of municipal solid waste (OFMSW) because it stabilizes biodegradable
organic matter and contributes to reduce the quantity of municipal solid waste to be incinerated or land-filled. However,
the composting process generates environmental impacts such as atmospheric emissions and resources consumption that should
be studied. This work presents the inventory data and the study of the environmental impact of two real composting plants
using different technologies, tunnels (CT) and confined windrows (CCW).
Materials and methods Inventory data of the two composting facilities studied were obtained from field measurements and from plant managers. Next,
life cycle assessment (LCA) methodology was used to calculate the environmental impacts. Composting facilities were located
in Catalonia (Spain) and were evaluated during 2007. Both studied plants treat source separated organic fraction of municipal
solid waste. In both installations the analysis includes environmental impact from fuel, water, and electricity consumption
and the main gaseous emissions from the composting process itself (ammonia and volatile organic compounds).
Results and discussion Inventory analysis permitted the calculation of different ratios corresponding to resources consumption or plant performance
and process yield with respect to 1 t of OFMSW. Among them, it can be highlighted that in both studied plants total energy
consumption necessary to treat the OFMSW and transform it into compost was between 130 and 160 kWh/t OFMSW. Environmental
impact was evaluated in terms of global warming potential (around 60 kg CO2/t OFMSW for both plants), acidification potential (7.13 and 3.69 kg SO2 eq/t OFMSW for CT and CCW plant respectively), photochemical oxidation potential (0.1 and 3.11 kg C2H4 eq/t OFMSW for CT and CCW plant, respectively), eutrophication (1.51 and 0.77 kg /t OFMSW for CT and CCW plant, respectively), human toxicity (around 15 kg 1,4-DB eq/t OFMSW for both plants) and ozone layer
depletion (1.66 × 10−5 and 2.77 × 10−5 kg CFC−11 eq/t OFMSW for CT and CCW plant, respectively).
Conclusions This work reflects that the life cycle perspective is a useful tool to analyze a composting process since it permits the comparison
among different technologies. According to our results total energy consumption required for composting OFMSW is dependent
on the technology used (ranging from 130 to 160 kWh/t OFMSW) as water consumption is (from 0.02 to 0.33 m3 of water/t OFMSW). Gaseous emissions from the composting process represent the main contribution to eutrophication, acidification
and photochemical oxidation potentials, while those contributions related to energy consumption are the principal responsible
for global warming.
Recommendations and perspectives This work provides the evaluation of environmental impacts of two composting technologies that can be useful for its application
to composting plants with similar characteristics. In addition, this study can also be part of future works to compare composting
with other OFMSW treatments from a LCA perspective. Likewise, the results can be used for the elaboration of a greenhouse
gasses emissions inventory in Catalonia and Spain. |
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Keywords: | Composting Environmental impact Forced-aerated windrow Greenhouse gasses emissions (GHG) In-vessel composting Life cycle assessment (LCA) Organic fraction of municipal solid waste (OFMSW) Turned windrow |
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