Life-Cycle Assessment Harmonization and Soil Science Ranking Results on Food-Waste Management Methods

This study reviewed 147 life cycle
studies, with 28 found suitable
for harmonizing food waste management methods’ climate and
energy impacts. A total of 80 scientific soil productivity studies
were assessed to rank management method soil benefits. Harmonized
climate impacts per kilogram of food waste range from −0.20
kg of carbon dioxide equivalents (CO2e) for anaerobic digestion
(AD) to 0.38 kg of CO2e for landfill gas-to-energy (LFGTE).
Aerobic composting (AC) emits −0.10 kg of CO2e.
In-sink grinding (ISG) via a food-waste disposer and flushing for
management with other sewage at a wastewater treatment plant emits
0.10 kg of CO2e. Harmonization reduced climate emissions
versus nonharmonized averages. Harmonized energy impacts range from
−0.32 MJ for ISG to 1.14 MJ for AC. AD at 0.27 MJ and LFGTE
at 0.40 MJ fall in between. Rankings based on soil studies show AC
first for carbon storage and water conservation, with AD second. AD
first for fertilizer replacement, with AC second, and AC and AD tied
for first for plant yield increase. ISG ranks third and LFGTE fourth
on all four soil-quality and productivity indicators. Suggestions
for further research include developing soil benefits measurement
methods and resolving inconsistencies in the results between life-cycle
assessments and soil science studies.