Thermophilic Solid-State Anaerobic Digestion of Corn Straw, Cattle Manure, and Vegetable Waste: Effect of Temperature, Total Solid Content, and C/N Ratio

Lignocellulose degradation, biogas production and characteristics of the microbial community in solid-state anaerobic digestion of wheat straw waste

Waste recycling is pivotal for deep space exploration or space habitation in life support systems (LSS) to enhance the material closure. This study investigated the enzymatic pretreatment and solid-state anaerobic digestion (SS-AD) of wheat straw as the major component of biomass waste in LSS for resource reclamation. Wheat straw compounds, such as cellulose, hemicellulose and lignin were significantly degraded after pretreatment with degradation at 37.47%, 46.96%, and 14.05%, respectively. SS-AD with the C/N ratio of 25 resulted in more intense lignocellulose degradation (74.20%) and more biogas yield (77.59 L/kg volatile solid) with 30 days digestion. The microbial community variation and diversity were analyzed that common fiber-degrading bacteria including Firmicutes, Bacteroidetes and Proteobacteria were dominant while the composition of the microbial genera shifted along with the digestion time. Moreover, a potential feasible strategy for biomass waste management in LSS by SS-AD was proposed.

Impact of Granular Activated Carbon on Anaerobic Process and Microbial Community Structure during Mesophilic and Thermophilic Anaerobic Digestion of Chicken Manure

In this work, the impact of granular activated carbon (GAC) on the mesophilic and thermophilic anaerobic digestion of chicken manure and the structure of microbial communities was investigated. These results demonstrated that GAC supplementation effectively enhanced the consumption of produced organic acids in the mesophilic and thermophilic batch tests, accompanied by faster biomethane production in the presence of GAC than from reactors without GAC. However, since the free ammonia level was 3–6 times higher in the thermophilic reactors, this led to the instability of the anaerobic digestion process of the nitrogen-rich substrate at thermophilic temperatures. Bacteroidia and Clostridia were the two main bacterial classes in the mesophilic reactors, whereas the class Clostridia had a competitive advantage over other groups in the thermophilic systems. The archaeal communities in the mesophilic reactors were mainly represented by representatives of the genera Methanosarcina, Methanobacterium, and Methanotrix, whereas the archaeal communities in the thermophilic reactors were mainly represented by members of the genera Methanosarcina, Methanoculleus, and Methanothermobacter. New data obtained in this research will help control and manage biogas reactors in the presence of GAC at different temperatures.

Biological Processes for Pollution Control: Current Research and Emerging Technologies 2020

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