Life cycle assessment of the integration of anaerobic digestion and pyrolysis for treatment of municipal solid waste

The integration of anaerobic digestion (AD) and pyrolysis (Py) could be a solution to economically utilize the organic fraction of municipal solid waste (OFMSW). However, it is not clear whether the environmental impact of the integrated pathway always outperforms the two single technologies. In this study, two integrated pathways (AD-Py, Py-AD) were compared with single AD and Py from the life cycle environmental impacts point of view. The results indicate that the environmental impacts of the four pathways are heavily dependent on their energy inputs and outputs. AD-Py is more environmentally friendly (-11.53 of total environmental impact /kg OFMSW) than single AD or Py. Py-AD exhibites the heaviest environmental burden (2.75 of total environmental impact /kg OFMSW) in all pathways. Therefore, AD-Py can be the top priority of treating OFMSW among the four pathways from the environmental viewpoint. This work could provide a theoretical support for the utilization of OFMSW.

Automated summary

By comparing the environmental impacts of anaerobic digestion-pyrolysis and pyrolysis-anaerobic digestion integrations with single anaerobic digestion and pyrolysis technologies for organic solid waste, it was found that anaerobic digestion-pyrolysis has the least environmental impact, while pyrolysis-anaerobic digestion exhibits the heaviest environmental burden. Hence, the anaerobic digestion-pyrolysis integration is considered the top priority for treating organic solid waste from an environmental perspective.