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Comparison and Gas Loading Impact on Counter- and Concurrent Trickle-Bed Reactor Configurations for Ex-Situ Biomethanation


 In this work, the two different configurations (counter- and concurrent) of laboratory scale trickle-bed reactors for ex-situ biomethanation were studied under continuous operation. Reactors operating at thermophilic conditions (50°C) were fed with H2 and CO2 (ratio 4:1) while cow manure used as liquid phase and source of nutrients for microbiota. Studies were performed at the gas loading rate ranging from 10 m3/m3/d to 30 m3/m3/d. The counter-current configuration performed better and had a higher stability compared to concurrent configuration. It achieved 96.1 ± 2.5% of CH4 at gas loading 10 m3/m3/d compared to 86.4 ± 3.3% of CH4 in concurrent at the same loading. At gas loadings >15 m3/m3/d, the concurrent configuration had unstable performance (decreasing CH4 content), while the counter-current reactor exhibited stable performance even at the highest studied loading (30 m3/m3/d), with 68.5 ± 2.5% of CH4. The hydrogenotrophic methanogens such as Methanobacterium (45.7-64.9%) and Methanothermobacter prevailed in both configurations.