Effect of Aerobic Hydrolysis on Anaerobic Fermentation Characteristics of Various Parts of Corn Stover and the Scum Layer

Abstract

To solve the difficulty of lignocellulose hydrolysis and the formation of crusted scum in anaerobic fermentation, various parts of corn stover, i.e., pith, rind and leaf, were subjected to a two-phase processing including aerobic hydrolysis (AH) and anaerobic fermentation. The results showed that AH significantly broke down the lignin structure of the various components of corn stover and increased the rate of lignin degradation. After 16 h of AH, the lignin degradation rates of the pith, rind and leaf were 4.20%, 3.91% and 4.90%, respectively, and the acetic acid produced accounted for more than 60% of the total amount of volatile fatty acids (VFAs) and ethanol. After hydrolyzing the pith and rind for 12 h and the leaf for 8 h, the maximum methane yields of fresh mass volatile solid (VS) were 323 ml g-1, 251 ml g-1 and 264 ml g-1, respectively, which were increased by 35.02%, 30.05% and 8%, respectively, while the fermentation cycle of T90 (90% of the total gas production) was shortened by 4-5 days. After hydrolyzing the rind and leaf for 12 h and the pith for 16 h, the thicknesses of the scum layer were only 7.1%, 13.6% and 18%, respectively, of that of the untreated group, indicating that AH coupled with anaerobic fermentation can effectively degrade lignin, reduce the thickness of the scum layer and increase the methane yield.

Effects of urea ammonia pretreatment on the batch anaerobic fermentation efficiency of corn stovers

“…In this experiment, the decrement in the lignin degradation was slight. The results of the lignocellulose degradation presented here were are lower than those obtained by Zhang et al [32] , whose degradation rate was about 25% after 16 h of aerobic hydrolysis pretreatment. The respective degradation rates of the lignocellulose during the anaerobic fermentation process are depicted in Figure 5.…”

Effect of Particle Size on the Aerobic and Anaerobic Digestion Characteristics of Whole Rice Straw

“…In this study, aeration was performed during the hydrolysis and acidification steps of AD, namely aerobic hydrolysis and acidification, to accelerate the growth of hydrolysis and acidification bacteria, thereby obtaining higher extracellular hydrolytic enzymes in the presence of sufficient oxygen. In addition, a published study has proved that lignin can hardly be degraded under anaerobic conditions [10]. Molecular oxygen contributes to open the side chain of lignin and depolymerize the dense structure of lignocellulose, promoting its utilization by microorganisms.…”

A Comprehensive Characterization of Different Fractions of Corn Stover and Their Relationships to Multipollutant Sorption Characteristics

“…There are also some absorption peaks within the range 2000-1550 cm -1 , which indicates the presence of lignin in corn stover [47]. The absorption band at approximately 1034 cm -1 might correspond to the stretching vibration of C-O due to the presence of hemicellulose [22–24]. The glycosidic linkages in cellulose are indicated by the peak at 896 cm -1 .…”

“…With different morphologies, CSL had a relatively rough surface compared with the other two parts. The coarse and disordered fibres contained in CSL could increase the pore volume and external surface area of the material [22][23][24].…”

“…The production level of corn is one of the largest among the crops in the world and can result in a large quantity of stover waste after harvest. In developing countries, most of the stover is disposed of by direct dumping or burning in the field without effective utilization, which causes serious air pollution, such as haze, and damage to the land and the surrounding area [21][22][23][24]. This is a threat to the ecological environment.…”