A comparative study of thermophilic and mesophilic anaerobic co-digestion of food waste and wheat straw: Process stability and microbial community structure shifts. (May 2018)

• Record Type: Journal Article
• Authors: Shi, Xuchuan; Guo, Xianglin; Zuo, Jiane; Wang, Yajiao; Zhang, Mengyu
• Is Part Of: Waste management. Volume 75(2018)
• Page Start: 261
• Page End: 269
• Publication Date: 2018-05
• Subjects: AD Anaerobic digestion -- FW Food waste -- WS Wheat straw -- OLRs organic loading rates -- TS Total solid -- VS Volatile solid -- TAD Thermophilic anaerobic digestion -- MAD Mesophilic anaerobic digestion -- VFA Volatile fatty acid; Anaerobic co-digestion -- Thermophilic and mesophilic -- Food waste and wheat straw -- Microbial community shift; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2018.02.004
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: A comprehensive comparison of thermophilic and mesophilic anaerobic co-digestion. Thermophilic condition increased methane production and process stability. Co-digestion of food waste and wheat straw shows positive synergetic effects. Thermophilic reactor has high population of lignocellulose-degrading microorganisms. Abstract: Renewable energy recovery from organic solid waste via anaerobic digestion is a promising way to provide sustainable energy supply and eliminate environmental pollution. However, poor efficiency and operational problems hinder its wide application of anaerobic digestion. The effects of two key parameters, i.e. temperature and substrate characteristics on process stability and microbial community structure were studied using two lab-scale anaerobic reactors under thermophilic and mesophilic conditions. Both the reactors were fed with food waste (FW) and wheat straw (WS). The organic loading rates (OLRs) were maintained at a constant level of 3 kg VS/(m 3 ·d). Five different FW:WS substrate ratios were utilized in different operational phases. The synergetic effects of co-digestion improved the stability and performance of the reactors. When FW was mono-digested, both reactors were unstable. The mesophilic reactor eventually failed due to volatile fatty acid accumulation. The thermophilic reactor had better performance compared to mesophilic one. The biogas production rate of the thermophilic reactor was 4.9–14.8% higher than that of mesophilic reactor throughout the experiment. The shifts in microbial community structures throughout the experiment in both thermophilic and mesophilic reactors were investigated. With increasing FW proportions, bacteria belonging to the phylum Thermotogae became predominant in the thermophilic reactor, while the phylum Bacteroidetes was predominant in the mesophilic reactor. The genus Methanosarcina was the predominant methanogen in the thermophilic reactor, while the genus Methanothrix remained predominant in the mesophilic reactor. The methanogenesis pathway shifted from acetoclastic to hydrogenotrophic when the mesophilic reactor experienced perturbations. Moreover, the population of lignocellulose-degrading microorganisms in the thermophilic reactor was higher than those in mesophilic reactor, which explained the better performance of the thermophilic reactor.