BACKGROUND: Oxidative lime pretreatment (OLP) is an effective pretreatment for highly recalcitrant lignocellulosic materials. This experiment was conducted to investigate the effect of short-term OLP on fermentative gas production kinetics of date palm prunings. Rachis and petiole were pretreated with excess lime (0.5 g Ca(OH)2 g(-1) dry matter) in a reactor charged with 10 bar pure oxygen pressure at different times and temperatures. RESULTS: Lignin removal was greatly affected by OLP, whereas cellulose was well preserved even after severe pretreatment. After 72 h fermentation, the cumulative gas production was 321.2 mL gas g(-1) organic matter (OM) for the most severe pretreatment, compared to 73.6 mL g(-1) OM for the untreated rachis. For the petiole pretreated at 120 °C for 280 min, 268 mL gas was produced compared to 59 mL gas g(-1) OM for the untreated petiole. Scanning electron microscope images showed the formation of pores (average diameter of 10-12 µm) and carbonate calcium deposits on the surface of treated biomass. An increase in biomass crystallinity was observed in pretreated samples resulting from cellulose enrichment. CONCLUSIONS: The results suggest that OLP improves the ruminal digestibility of date palm prunings, which may have potential for inclusion in the ruminant diet at low cost.
BACKGROUND: Oxidative lime pretreatment (OLP) is an effective pretreatment for highly recalcitrant lignocellulosic materials. This experiment was conducted to investigate the effect of short-term OLP on fermentative gas production kinetics of date palm prunings. Rachis and petiole were pretreated with excess lime (0.5 g Ca(OH)2 g(-1) dry matter) in a reactor charged with 10 bar pure oxygen pressure at different times and temperatures. RESULTS:Lignin removal was greatly affected by OLP, whereas cellulose was well preserved even after severe pretreatment. After 72 h fermentation, the cumulative gas production was 321.2 mL gas g(-1) organic matter (OM) for the most severe pretreatment, compared to 73.6 mL g(-1) OM for the untreated rachis. For the petiole pretreated at 120 °C for 280 min, 268 mL gas was produced compared to 59 mL gas g(-1) OM for the untreated petiole. Scanning electron microscope images showed the formation of pores (average diameter of 10-12 µm) and carbonate calcium deposits on the surface of treated biomass. An increase in biomass crystallinity was observed in pretreated samples resulting from cellulose enrichment. CONCLUSIONS: The results suggest that OLP improves the ruminal digestibility of date palm prunings, which may have potential for inclusion in the ruminant diet at low cost.