A reused method for molasses-processed wastewater: Effect on silage quality and anaerobic digestion performance of Pennisetum purpereum

Abstract

The silage quality and anaerobic digestion performance of Pennisetum purpereum with molasses-processed wastewater addition were assessed. The silage samples with molasses-processed wastewater addition obtained higher lactic acid concentration of 15.18-23.38mg/g FM, lower pH value of 3.96-4.45 and lower NH₃-N content of 0.47-0.64mg/g FM. No obvious difference was observed in the dominant phyla and genus, but the relative abundance of Lactobacillus reached up to 77.39%, increased by 84% compared to the silage samples without molasses-processed wastewater addition. Combined the silage quality and bacterial community, the decreased in pH value of fresh material caused by molasses-processed wastewater addition was the main reason for improving the silage quality. Meanwhile, the increased in COD concentration is beneficial for improving the specific methane yield and the maximum specific methane yield of 259±5.75mL/g VS was obtained with adding 20g/kg molasses-alcoholic wastewater. Molasses-processed wastewater is an alternative additive for silage.

Keywords: Anaerobic digestion; Molasses-processed wastewater; Pennisetum purpereum; Silage.