Effects of NaOH Pretreatment on the Microbial Community and Its Enzymatic Activities in Anaerobic Digestion of Chicken Manure and Straw

Abstract

NaOH pretreatment straw and chicken manure were mixed in different proportions to study the performance of anaerobic fermentation gas production of mixed materials with different proportions. The results showed that the pretreatment with 2% NaOH had the best effect on the gas production efficiency and cumulative gas production. After the pretreatment with NaOH, at the genus level, the main active flora was unidentified_Spirochaetaceae, unidentified_Prevotellaceae, uniden-tified_Lentimicrobiaceae, Lactobacillus, and Bacteroides. The highest peaks of amylase, protease, and cellulase activities were 308.73 IU/L, 121.03 IU/L, and 270.18 U/mL, respectively. The number of microbial colonies was positively correlated with the activity of the corresponding enzyme. With the increase of the proportion of straw in the raw materials, the activities of various hydrolases increased by 2.8%~28%. When the straw amount was 3%, the utilization rate of the raw material increased by optimization of C/N, and the efficiency of anaerobic digestion improved.