Biogas Production Potential of Thermophilic Anaerobic Biodegradation of Organic Waste by a Microbial Consortium Identified with Metagenomics

Abstract

Anaerobic digestion (AD) is a widespread biological process treating organic waste for green energy production. In this study, wheat straw and corn stalks without any harsh preliminary treatment were collected as a renewable source to be employed in a laboratory-scale digester to produce biogas/biomethane. Processes parameters of temperature, pH, total solids, volatile solid, concentration of volatile fatty acids (VFA), and cellulose concentration, were followed. The volume of biogas produced was measured. The impact of organic loading was stated, showing that the process at 55 °C tolerated a higher substrate load, up to 45 g/L. Further substrate increase did not lead to biogas accumulation increase, probably due to inhibition or mass transfer limitations. After a 12-day anaerobic digestion process, cumulative volumes of biogas yields were 4.78 L for 1 L of the bioreactor working volume with substrate loading 30 g/L of wheat straw, 7.39 L for 40 g/L and 8.22 L for 45 g/L. The degree of biodegradation was calculated to be 68.9%, 74% and 72%, respectively. A fast, effective process for biogas production was developed from native wheat straw, with the highest quantity of daily biogas production occurring between day 2 and day 5. Biomethane concentration in the biogas was 60%. An analysis of bacterial diversity by metagenomics revealed that more than one third of bacteria belonged to class Clostridia (32.9%), followed by Bacteroidia (21.5%), Betaproteobacteria (11.2%), Gammaproteobacteria (6.1%), and Alphaproteobacteria (5%). The most prominent genera among them were Proteiniphilum, Proteiniborus, and Pseudomonas. Archaeal share was 1.37% of the microflora in the thermophilic bioreactor, as the genera Methanocorpusculum, Methanobacterium, Methanomassiliicoccus, Methanoculleus, and Methanosarcina were the most abundant. A knowledge of the microbiome residing in the anaerobic digester can be further used for the development of more effective processes in conjunction with theidentified consortium.

An Investigation of Temperature Downshift Influences on Anaerobic Digestion in the Treatment of Municipal Wastewater Sludge

“…Psychrophilic (< 20°C), mesophilic (30-40°C), and thermophilic (50-60°C) temperatures are all common temperatures for the AD process [13,14]. Several studies have explored the potential for biogas production from municipal wastewater sludge under various thermal conditions [15][16][17].…”

Effects of phenyl acids on different degradation phases during thermophilic anaerobic digestion

“…In previous investigations, Pseudomonas spp. was one of the most abundant bacteria during thermophilic AD of organic waste ( Kabaivanova et al, 2022 ), a key-player for a stable AD of carbohydrates ( Buettner et al, 2019 ) and able to exploit VFAs ( Jie et al, 2014 ).…”

Algal Biomass Accumulation in Waste Digestate after Anaerobic Digestion of Wheat Straw

“…Two different biotechnological processes were performed for anaerobic digestion of wheat straw at mesophilic conditions (35 • C) and at thermophilic conditions (55 • C). Anaerobic digestion processes were performed on a laboratory scale, as previously described [21]. Characteristics of the source digestates-total solids (TS), volatile solids (VS), chemical oxygen demand (COD), nitrogen, phosphorus, and pH are presented in Table 1.…”