Effects of carbon source variability on enhanced Bio-hydrogen production.

This study investigated how glucose, starch, and rapeseed oil, three common food waste components with diverse molecular and physicochemical characteristics, influenced hydrogen production and microbial communities in dark fermentation under varying carbon/nitrogen (C/N) ratios. The results indicated that glucose and starch groups, significantly increased hydrogen yields to 235 mL H2/gVS (C/N = 40) and 234 mL H2/gVS (C/N = 40), respectively, while rapeseed oil, with a lower yield of 30 mL H2/gVS (C/N = 20), demonstrated a negative impact. Additionally, an accumulation of propionate was observed with increasing carbon source complexity, suggesting that simpler carbon sources favored hydrogen production and bacterial growth. Conversely, lipid-based materials required rigorous pre-treatment to mitigate their inhibitory effects on hydrogen generation. Overall, this study underscores the importance of carbon source selection, especially glucose and starch, for enhancing hydrogen production and microbial growth in dark fermentation, while highlighting the challenges posed by lipid-rich substrates that require intensive pre-treatment to optimize yields.

Interactive effects of carbohydrate, lipid, protein composition and carbon/nitrogen ratio on biogas production of different food wastes.

The anaerobic co-digestion (AcoD) of FWs produces variable methane yields, mainly due to variable carbon/nitrogen (C/N) ratio and proportions of lipids (L), carbohydrates (C), and proteins (P) in different FW samples. In this study, a significant interaction between C/N ratio and LCP composition was found and contributed to the differing trends between special (SMP) and theoretical methane production. The highest SMP of 595 mL CH4 gVS-1 occurred at C/N of 25 and LCP of 63.25:22.62:14.13, followed by 592 mL CH4 gVS-1 at C/N of 30 and LCP of 48.94:39.74:11.32, which also reflected their interaction. Attributing to their interactive effect on obtaining optimal process parameters and microbial community, the inhibition threshold of lipid as well as the methane yield was increased. Understanding the interaction between C/N ratio and LCP composition is an effective and promising way to obtain suitable mixture ratios of organic wastes under AcoD.

Effects of waste sources on performance of anaerobic co-digestion of complex organic wastes: taking food waste as an example.

Few studies have addressed how to blend wastes for anaerobic co-digestion. This study investigated the effects of waste sources on anaerobic co-digestion (AcoD) performance, by varying the quality of food wastes (FWs) from six sources in Xi'an region, China that were individually co-digested with pre-treated corn straw and cattle manure. These effects were analysed in terms of their volatile solid (VS) ratios, C/N ratios, and the chemical composition of the FWs. The results indicated that the VS ratios were not suitable as a common mixture method because the VS ratios at which the best methane potentials occurred differed significantly among the six FW groups. The C/N ratios within a 17-24 range resulted in better methane potentials when the FWs were co-digested with other wastes. Synergistic effects were found among the carbohydrates, proteins, and lipids of the FWs; however, the optimum ratios of these components could not be determined. Thus, the C/N ratio is recommended as a mixture method when co-digesting FWs with other organic wastes in selected region.