Optimization of volatile fatty acids from food wastes for polyhydroxyalkanoates synthesis

Abstract This study considered production of volatile fatty acids (VFAs) through anaerobic digestion of food wastes for subsequent usage as raw materials for polyhydroxyalkanoates (PHAs) synthesis. Four types of food wastes including yam, plantain, pineapple, and watermelon peels, as well as their combinations, were initially digested anaerobically to determine the food wastes with highest production of VFA concentration. Yam and plantain peel mix was found to produce highest VFA concentration and yield, measuring 12.78 g/l and 0.64gVFA/gVS, respectively. This necessitated the use of the mix in a semi-continuous process for VFA production. For organic loading rate ranges between 1 and 4gVS/m 3 /day, acetic acid was observed to be dominant VFA accounting for 50.62% of total VFAs produced while butyric acid accounted for 29.84%. The statistical ANOVA regression, based on the experimental values obtained when VFA was used as a carbon source for PHA production, showed that the modeling algorithms provide a reasonably solid estimate of the PHA yield with the highest expected yield of 56.15% PHAs occurring at a VFA concentration of 2 g/l.