Environmental assessment of waste feedstock mono-dimensional and bio-refinery systems: Combining manure co-digestion and municipal waste anaerobic digestion

6
Mar

Environmental assessment of waste feedstock mono-dimensional and bio-refinery systems: Combining manure co-digestion and municipal waste anaerobic digestion

Organic municipal solid waste (OMSW) as a feedstock for energy recovery and material recycling offers
the potential to reduce environmental impacts from energy production while displacing emission intensive
waste management strategies such as landfills. This paper quantifies the environmental
impact of anaerobic digestion of local, residual biomass. A life-cycle assessment was jointly performed
for two scenarios for the biological treatment of local organic municipal solid waste and pig manure in
the Netherlands. Scenario 1 was a separate treatment using anaerobic digestion, and Scenario 2 was a
bio-refinery system that integrates anaerobic digestion of organic, municipal solid waste, and co-digestion
of pig manure and other organic co-substrates. For both scenarios, electricity and heat are
generated using a combined heat and power engine. The bio-refinery system (Scenario 2) contribution to
climate change resulted in 0.16 Mt CO2 eq./yr, which is lower than the 0.17 Mt CO2 eq./yr of Scenario 1.
Both scenarios are found to be beneficial with regard to resource depletion and human toxicity. The
integration of organic waste and manure anaerobic digestion has no effect on acidification and terrestrial
eutrophication impact categories, resulting in 43.59 AE eq. and 86.33 AE eq. for Scenario 1 and 43.58 AE
eq. and 86.30 AE eq. for Scenario 2. Moreover, Scenario 2 yields 18% lower emissions than those from
natural gas derived electricity in the Netherlands. The biorefinery system represents an opportunity to
improve organic waste-management strategies, at the same time as reducing the environmental impact
from energy production and the costs for surplus manure disposal by producing high-quality commodities
that can be traded on the market.

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