Impact of nano structure of agro-industrial by-products on biogas production kinetics and methane emission.

Over the past decades, the agro-industrial by-products (AIBP) have received considerable attention. In this context, we aimed to investigate the effect of AIBP as a source of non-fiber carbohydrates on biogas production kinetic, methane emission, and fermentation characteristics. Experimental treatments were (1) sugar beet pulp (SBP) (control), (2) apple pomace (AP), (3) orange pulp (OP, (4) 33% AP + 66% OP, (5) 50% AP + 50% OP, and (6) 66% AP + 33% OP. Field emission scanning electron microscope was used to show the nano structural differences of the AIBP. Results of proximate analyzes, demonstrated significant differences of the crude protein among the treatments (P < 0.05). Biogas production and methane emission were significantly higher in SBP and OP treatments (P < 0.05). The highest and the lowest amounts of acetate were observed for AP and OP (61.84 mmol/L, 58.15 mmol/L), respectively. More broken edges were obvious in OP images. Yet, particle size was rather smaller in SBP. Images of AP showed a sleek surface which may act as a shield preventing more digestion. To conclude, utilization of AIBP, as non-fiber energy source, not only could contribute towards reducing environmental contamination but could also positively affect degradation, biogas kinetics, methane emission and in vitro fermentation parameters. [ABSTRACT FROM AUTHOR]