توليد بيوهيدروژن از ضايعات غذايي با استفاده از تخمير تاريك و استفاده از اسيدهاي چرب فرار باقي مانده براي سنتز پروتئين تك‌ياخته

Biohydrogen Production from Food Waste by Dark Fermentation an‎d Utilization of Residual Volatile Fatty Acids (VFAs) for Single Cell Protein Synthesis

زيست فناوري

Food waste, owing to its high content of biodegradable organic matter, represents a suitable substrate for the biological production of energy an‎d value-added products. This study aimed to enhance biohydrogen production from restaurant food waste through the eva‎luation of different pretreatment an‎d dark fermentation conditions, followed by the utilization of residual organic matter in the liquid obtained from dark fermentation for fungal biomass production. To increase the release of fermentable compounds, the food waste was subjected to autohydrolysis an‎d dilute sulfuric acid pretreatments at acid concentrations of 0.5 an‎d 1%, temperatures of 130 an‎d 150 °C, an‎d treatment times of 30 an‎d 60 min. The solid an‎d liquid fractions obtained from each treatment were separately fermented with Enterobacter aerogenes at initial pH values of 5 an‎d 7. Biohydrogen production, volatile fatty acids (VFAs), ethanol, an‎d soluble chemical oxygen deman‎d (SCOD) were eva‎luated, an‎d the liquid obtained under the selec‎ted dark fermentation condition was subsequently used as the cultivation medium for Aspergillus oryzae. The results showed that pretreatment increased the specific biohydrogen yield by approximately five- to seven-fold compared with the untreated sample, an‎d an initial pH of 7 was associated with higher yields in most treatments. The highest biohydrogen production on a mass-balance basis, equivalent to 121.18 L H₂/kg raw food waste, was obtained with 1% sulfuric acid pretreatment at 150 °C for 60 min an‎d an initial pH of 7. The highest specific hydrogen yield was 233.76 mL H₂/g volatile solids. The liquid obtained under the selec‎ted dark fermentation condition still contained 13.30 g/L SCOD an‎d 3.25 g/L VFAs, indicating the presence of residual soluble organic matter an‎d the potential for further utilization of this stream in the second stage. Cultivation of A. oryzae in this liquid medium produced 450.50 g dry fungal biomass/kg raw food waste. The final biomass contained 31.10% crude protein, 6.80% fat, 9.60% fiber, an‎d 38.76% carbohydrates, with a calculated energy value of 359.84 kcal/100 g. Essential amino acids, including lysine, threonine, tryptophan, an‎d methionine, were identified in the biomass, while the measured undesirable elements were below the reference limits used for feed materials. Overall, the results demonstrated the feasibility of a two-stage biorefinery system for the sequential production of biohydrogen an‎d protein-rich fungal biomass from food waste at the laboratory scale an‎d indicated the potential of the resulting biomass for further eva‎luation in animal feed applications.

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