Effect on anaerobic digestion performance of corn stover by freezing-thawing with ammonia pretreatment

In order to enhance the biomethane production from corn stover, choosing effective pretreatment is one of the necessary steps before starting anaerobic digestion (AD). This study was aimed to analyze the effectiveness of freezing-thawing with ammonia pretreatment on substance degradation and AD performance of corn stover. Three ammonia concentrations (2%, 4%, and 6%) with two different moisture contents (50% and 70%) were used to pretreat the corn stover at two temperatures (-20 degrees C and 20 degrees C). The result showed that an optimum pretreatment condition for corn stover was at the temperature of -20 degrees C, moisture content of 70% and ammonia concentration of 2%. Under the optimum pretreatment condition, the maximum biomethane yield reached 261 ml.(g VS)(-1), which was 41.08% higher than that of the untreated. Under different pretreatment conditions, the highest loss of lignin at - 20 degrees C with 2% ammonia concentration was 63.36% compared with the untreated. The buffer capacity of AD system was also improved after the freezing-thawing with ammonia pretreatment. Therefore, the freezing-thawing with ammonia pretreatment can be used to improve AD performance for corn stover. This study provides further insight for exploring an efficient freezing-thawing with ammonia pretreatment strategy to enhance AD performance for the practical application. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.