Impacts of mycotoxin on biohydrogen production from waste dry fruits

Discarded dry fig and raisin, which exporting companies have to claim and destroy, were subjected to batch dark fermentation at 37 degrees C with pretreated anaerobic sludge in an incubator to investigate the effect of mycotoxin on biohydrogen production. The need for pretreatment was evaluated. Pretreatment had no significant effect on enhancing biohydrogen production at comparison of the same substrates. However, it had a significant positive effect on comparison of yield ratios when mycotoxin presence was observed. The CHF of dry fig and raisin without pretreatment (81 mL, 56 mL, respectively) was lower than mycotoxin-free substrates (267 mL, 180 mL, respectively). In mycotoxic wastes, the VFA concentration was very high, inhibiting biohydrogen formation. Furthermore, mycotoxins and their by-products after pretreatment may cause the bacterial mechanism to shift into different hydrogen-consuming end products. In mycotoxin-free substrates, there was around 2.2-2.5 g L-1 acetate and 1.1-1.7 g L-1 butyrate, enhancing biohydrogen production potential. The highest biohydrogen production yield was observed with mycotoxin-free dry fig without pretreatment (79 mL H-2 g(-1) total sugar). The dry fig without mycotoxin produced the highest SHPR (42.3 ml H-2 g(-1) cell mass h(-1)). Mycotoxin has a clear negative impact on biohydrogen production potential, biohydrogen production yield, and SHPR.