Anaerobic co-digestion of commercial food waste and dairy manure: Characterizing biochemical parameters and synergistic effects.

Anaerobic digestion of commercial food waste is a promising alternative to landfilling commercial food waste. This study characterized 11 types of commercial food wastes and 12 co-digestion blends. Bio-methane potential, biodegradable fraction, and apparent first-order hydrolysis rate coefficients were reported based upon biochemical methane potential (BMP) assays. Food waste bio-methane potentials ranged from 165 to 496 mL CH4/g VS. Substrates high in lipids or readily degradable carbohydrates showed the highest methane production. Average bio-methane potential observed for co-digested substrates was -5% to +20% that of the bio-methane potential of the individual substrates weighted by VS content. Apparent hydrolysis rate coefficients ranged from 0.19d(-1) to 0.65d(-1). Co-digested substrates showed an accelerated apparent hydrolysis rate relative to the weighted average of individual substrate rates. These results provide a database of key bio-digestion parameters to advance modeling and utilization of commercial food waste in anaerobic digestion.

Lifecycle Greenhouse Gas Analysis of an Anaerobic Codigestion Facility Processing Dairy Manure and Industrial Food Waste.

Anaerobic codigestion (AcoD) can address food waste disposal and manure management issues while delivering clean, renewable energy. Quantifying greenhouse gas (GHG) emissions due to implementation of AcoD is important to achieve this goal. A lifecycle analysis was performed on the basis of data from an on-farm AcoD in New York, resulting in a 71% reduction in GHG, or net reduction of 37.5 kg CO2e/t influent relative to conventional treatment of manure and food waste. Displacement of grid electricity provided the largest reduction, followed by avoidance of alternative food waste disposal options and reduced impacts associated with storage of digestate vs undigested manure. These reductions offset digester emissions and the net increase in emissions associated with land application in the AcoD case relative to the reference case. Sensitivity analysis showed that using feedstock diverted from high impact disposal pathways, control of digester emissions, and managing digestate storage emissions were opportunities to improve the AcoD GHG benefits. Regional and parametrized emissions factors for the storage emissions and land application phases would reduce uncertainty.

Life cycle assessment integrated with thermodynamic analysis of bio-fuel options for solid oxide fuel cells.

A methodology that integrates life cycle assessment (LCA) with thermodynamic analysis is developed and applied to evaluate the environmental impacts of producing biofuels from waste biomass, including biodiesel from waste cooking oil, ethanol from corn stover, and compressed natural gas from municipal solid wastes. Solid oxide fuel cell-based auxiliary power units using bio-fuel as the hydrogen precursor enable generation of auxiliary electricity for idling heavy-duty trucks. Thermodynamic analysis is applied to evaluate the fuel conversion efficiency and determine the amount of fuel feedstock needed to generate a unit of electrical power. These inputs feed into an LCA that compares energy consumption and greenhouse gas emissions of different fuel pathways. Results show that compressed natural gas from municipal solid wastes is an optimal bio-fuel option for SOFC-APU applications in New York State. However, this methodology can be regionalized within the U.S. or internationally to account for different fuel feedstock options.