Keywords: solid waste management, life cycle assessment, LCA, composting, anaerobic digestion, industrial ecology, municipal waste, organic waste, Mauritius, life cycle inventory, energy consumption, air emission, global warming, biological waste treatment
Life Cycle Assessment technique for sound management of organic municipal solid wastes
Mauritius generates around 1200 tonnes of municipal solid wastes on a daily basis, out of which more than 60% is of organic nature. The objective of this paper was to evaluate two different strategies for the treatment of organic wastes on a life cycle perspective, namely: composting and Anaerobic Digestion (AD). The functional unit was one ton of organic municipal solid wastes. Windrow technology was considered for composting while a reactor system was chosen for the AD. The life cycle inventory showed that the energy consumption and air emissions were higher with AD. The gaseous emissions of NH3, H2S and HC were very low compared to emissions of CO2 and CH4 for both composting and AD. An overall environmental index of 0.135 was obtained for anaerobic digestion and 0.0104 for composting. The photochemical oxidant formation had a highest score of 0.0742 (a* 10-12) for AD whereas for composting, the largest score obtained was for global warming. Including the energy recovery from methane in the system boundaries decreased the overall environmental index for the AD process from 0.135 to 0.013.