Insights into organic matter evolution during food waste stabilization induced by 14-hour high-temperature fermentation

Large amounts of secondary pollutants are released during traditional composting, and rapid fermentation is desirable for the stabilization of food wastes. Food wastes were mixed with rice husk, placed in a bioreactor, and stirred continuously to achieve high-temperature fermentation for 14 h. The transformations of the mixtures were analyzed using elemental and spectral analysis combined with kinetic equations and two-dimensional correlation spectroscopy. The carbohydrates, proteins, and aliphatic compounds of food waste were degraded after 4 h of fermentation. Transformations of dissolved organic and sulfur- and nitrogen-containing substances followed first-order kinetic equations with reaction rate constants of 0.142 h(-1), 0.098 h(-1), and 0.016 h(-1), respectively. Organic matter conversion was in the following order: aliphatic -> protein -> carbohydrate and followed the order, acrylamide C -> O-alkyl C -> anomeric C at the molecular level. The fermentation process was characterized by the increase in protein- and fulvic-like compounds. Fulvic acid substances gradually accumulated during the late fermentation period. Thus, dissolved organic matter components were gradually transformed into humic substances with increasing fermentation time. The sequence of transformation during the fermentation process was, tyrosine-like -> tryptophan-like -> fulvic-like substances. Humification mainly occurred in the mature stage of composting; therefore, it was verified that the food waste was stabilized by a 14-h fermentation.

Automated summary

Large amounts of secondary pollutants can be released during traditional composting. A 14-hour high-temperature fermentation process using a bioreactor and rice husk was found to effectively stabilize food waste. The transformations of the waste were analyzed using various methods, and it was found that the degradation of carbohydrates, proteins, and aliphatic compounds occurred after 4 hours of fermentation. The process followed first-order kinetic equations with specific reaction rate constants.