Biomethanation in a thermophilic biotrickling filter — pH control and lessons from long-term operation. (September 2020)

• Record Type: Journal Article
• Authors: Ashraf, Muhammad Tahir; Sieborg, Mads Ujarak; Yde, Lars; Rhee, Chaeyoung; Shin, Seung Gu; Triolo, Jin Mi
• Is Part Of: Bioresource technology reports. Volume 11(2020)
• Publication Date: 2020-09
• Subjects: Biogas -- Biomethanation -- Hydrogenotrophic methanogenesis -- pH -- Upgrading; Biomass energy -- Periodicals; Biotransformation (Metabolism) -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Waste products as fuel -- Periodicals; Waste products as fuel; Organic wastes; Factory and trade waste; Biotransformation (Metabolism); Biomass energy; Agricultural wastes; Periodicals; Electronic journals; 662.88
• DOI: 10.1016/j.biteb.2020.100525
• Languages: English
• ISSNs: 2589-014X

Abstract

Abstract: Optimum pH for methanogenesis in an anaerobic digester is well known, however, the effect of pH and its control strategy for the ex-situ biomethanation is understudied. In this study, two pH control strategies, namely the addition of buffer media and the control of CO2 /H2 feed ratio, were investigated using a thermophilic biotrickling filter. Among the two, manipulating CO2 /H2 feed ratio was the more effective method to maintain pH below 8.5. The biomethanation was continued for 215 days with the gas retention time sequentially lowered down to 34 min, when an average methane production capacity of 8.54 ± 0.47 Nm 3 m r −3 d −1 was achieved. Microbial community analysis showed that >94% total archaea were Methanobacterium and Methanoculleus validating the prevalence of hydrogenotrophic methanogens in the system. Graphical abstract: Unlabelled Image Highlights: CO2 /H2 feed ratio >0.25 was found an effective way to maintain pH <8.5. Unconverted CO2 can maintain the bicarbonate buffer in the trickling media. Hydrogenotrophic methanogens were found to be the dominant archaea. Clogging of the BTF suggests a filtration system for the trickling media.