Anaerobic digestion + pyrolysis integrated system for food waste treatment achieving both environmental and economic benefits

Abstract

Waste-to-energy technologies for food waste (FW) and digestate treatment face environmental and economic barriers including pollutant emission and practical application concerns. This study investigated environmental impacts and economic feasibility of four scenarios to dispose 1 ton FW by life cycle assessment: Scenario A: mesophilic anaerobic digestion (AD) with digestate for biofertilizer; Scenario B: thermophilic AD with digestate for biofertilizer; Scenario C: mesophilic AD combining with digestate for 400 °C pyrolysis; and Scenario D: thermophilic AD combining with digestate for 700 °C pyrolysis. Scenario D was recommended for FW treatment especially for climate change, fine particulate matter formation, and Fossil depletion credits. Electrical recovery was identified as the most contributing and sensitive factor based on uncertainty and sensitivity analysis. Optimizing electrical generation efficiency from 39 % to 44 % benefited all 17 environmental categories through scenario analysis. Furthermore, Scenario D showed an economic advantage over the other scenarios, which was attributed to digestate post-treatment by 700 °C pyrolysis. This study provided a comprehensive reference for FW and digestate management.