Additional ratios of hydrolysates from lignocellulosic digestate at different hydrothermal temperatures influencing anaerobic digestion performance

• Published in: Environmental science and pollution research international 2023-03, Vol.30 (12), p.32866-32881
• Main Authors: Wang, Jing, Zhao, Nannan, Zhang, Xuan, Jiang, Lei, Kang, Ya-Ru, Chu, Yi-Xuan, He, Ruo
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biofuels; Bioreactors; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Lignin - metabolism; Methane; Research Article; Temperature; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 1614-7499; 1614-7499
• DOI: 10.1007/s11356-022-24519-y

Hydrothermal treatment (HT) is envisaged as a promising technology to treat the lignocellulosic biomass. HT temperature is an important parameter influencing the hydrolysate compositions such as organic compounds and potential inhibitors, and therefore affect the subsequential anaerobic digestion (AD) process. Herein, HT-AD was employed to treat the wheat straw-derived digestate. The HT temperature of 190 °C was proved to be the best performance with a higehst reducing sugar yield (45.05 mg g −1 ) in the hydrolysate and a highest methane yield (120.8 mL g TS −1 ) from the AD of the hydrolysate, which was 42.5% higher than the methane yield in the control without the hydrolysate addition (84.8 mL g TS −1 ). 3-Furaldehyde was the dominant organic in the hydrolysates. The HT temperature of 210 °C led to the presence of AD inhibitory moieties (e.g., phenols and furans) in the hydrolysate, resulting in a low methane yield. Although the treatments with the addition of 100% hydrolysate outperformed those of 50% hydrolysate in the methane yields in the late stage, the latter had higher methane yields in the first stage, suggesting that the additional ratios of hydrolysates should be carefully considered in AD, especially the detrimental effects of inhibitors and adaptability issues of AD consortia. The MiSeq sequencing showed that the hydrolysis/acidogenesis was dominant in the first stage, while methanogenesis became dominant in the late stage with the acetoclastic/hydrogenotrophic methanogens ( Methanosarcina and Methanobacterium ) enriched in the hydrolysate-feeding reactors. These findings demonstrated that a integration of HT-AD was a promising approach for the digestate valorization and to reduce the potential carbon emission from waste treatments.