Biogas and Volatile Fatty Acid Production During Anaerobic Digestion of Straw, Cellulose, and Hemicellulose with Analysis of Microbial Communities and Functions.

Jie Liu,Rui He,Xiaoyu Zuo,Luyao Yang,Rufei Liu,Ke Peng

doi:10.1007/s12010-021-03675-w

Abstract

The anaerobic digestion efficiency and methane production of strawwas limited by its complex composition and structure. In this study, rice straw (RS), cellulose, and hemicellulose were used as raw materials to study biogas production performance and changes in the volatile fatty acids (VFAs). Further, microbial communities and genetic functions were analyzed separately for each material. The biogas production potential of RS, cellulose, and hemicellulose was different, with cumulative biogas production of 283.75, 412.50, and 620.64mL/(g·VS), respectively. The methane content of the biogas produced from cellulose and hemicellulose was approximately 10% higher than that produced from RS after the methane content stabilized. The accumulation of VFAs occurred in the early stage of anaerobic digestion in all materials, and the cumulative amount of VFAs in both cellulose and hemicellulose was relatively higher than that in RS, and the accumulation time was 12 and 14days longer, respectively. When anaerobic digestion progressed to a stable stage, Clostridium was the dominant bacterial genus in all three anaerobic digestion systems, and the abundance of Ruminofilibacter was higher during anaerobic digestion of RS. Genetically, anaerobic digestion of all raw materials proceeded mainly via aceticlastic methanogenesis, with similar functional components. The different performance of anaerobic digestion of RS, cellulose, and hemicellulose mainly comes from the difference of composition of raw materials. Increasing the accessibility of cellulose and hemicellulose in RS feedstock by pretreatment is an effective way to improve the efficiency of anaerobic digestion. Since the similar microbial community structure will be acclimated during anaerobic digestion, there is no need to adjust the initial inoculum when the accessibility of cellulose and hemicellulose changes.

Highlights

Anaerobic digestion (AD) is a promising method for straw treatment, but the complex composition and structure of straw limit AD efficiency and methane production
The methane content of the biogas produced from cellulose and hemicellulose was approximately 10% higher than that produced from Rice straw (RS) after the methane content stabilized
When the AD progressed to the stable stage, there was no significant difference in microbial community and genetic function

Summary

Introduction

Anaerobic digestion (AD) is a promising method for straw treatment, but the complex composition and structure of straw limit AD efficiency and methane production. The main biodegradable components of straw are cellulose and hemicellulose. Because of the different chemical structures and physicochemical properties, the performance of AD of cellulose and hemicellulose is different, it’s different from that of straw. Research on the similarities and differences of AD of straw, cellulose and hemicellulose is helpful to clarify the law of anaerobic digestion of straw and provide theoretical basis for further improving the efficiency of anaerobic digestion. There are very few studies on AD using cellulose and hemicellulose as raw materials

Methods

Results

Conclusion