Anaerobic fermentation of biogas liquid pretreated maize straw by rumen microorganisms in vitro

• Anaerobic digestibility of maize straw improved by biogas liquid was explored.
• Statistical methods were used to optimize ammonia pretreatment.
• The physical structure was destroyed and degradation property increased.
• Nine days, 25 °C and 50% dosage of biogas liquid were found as the best condition.

This study intended to investigate the effect of pretreatment of maize straw with biogas liquid on followed fermentation by rumen microorganisms in vitro. The multiple effects including treated time, temperature and dosage of biogas liquid in pretreatment on the followed fermentation performance were analyzed by orthogonal array. The optimum conditions of pretreatment were 9 days, 25 °C and 50% (v/w) dosage of biogas liquid, which were indicated by the corresponding crystallinity index, dry matter digestibility (DMD) and acetate limiting-step concentration were 57.5%, 73.76% and 1756 mg/L, respectively. The ordering sequence of the influential factors for pretreatment was treated time > temperature > dosage of biogas liquid. The results of fermentation showed that the maize straw pretreated by biogas liquid was an efficient and economic pretreatment method of maize straw.