Anaerobic digestion of food waste using yeast

• Optimal conditions for the fermentative breakdown of food waste were identified.
• Yeast efficiently broke down food waste with loadings as high as 700 g FW/l.
• Optimum inoculation was ≈46 × 106 cells/175 ml, optimum temperature 40 °C.
• Metabolism of lipids was better than expected, starch mobilized after >20 days.
• CO2 and ethanol production only significant during days 0–7 of incubations.

Fermentative breakdown of food waste seems a plausible alternative to feeding food waste to pigs, incineration or garbage disposal in tourist areas. We determined the optimal conditions for the fermentative breakdown of food waste using yeast (Saccharomyces cerevisiae) in incubations up to 30 days. Yeast efficiently broke down food waste with food waste loadings as high as 700 g FW/l. The optimum inoculation was ≈46 × 106 cells/l of culture with a 40 °C optimum (25–40 °C). COD and BOD were reduced by ≈30–50%. Yeast used practically all the available sugars and reduced proteins and lipids by ≈50%. Yeast was able to metabolize lipids much better than expected. Starch was mobilized after very long term incubations (>20 days). Yeast was effective in breaking down the organic components of food waste but CO2 gas and ethanol production (≈1.5%) were only significant during the first 7 days of incubations.