Selective Removal of Water Generated during Hydrogenotrophic Methanation from Culture Medium Using Membrane Distillation

Abstract

Methane production was carried out in two different types of reactors using a thermophilic and hydrogenotrophic methanogen, Methanothermobacter sp. KEPCO-1, which converts hydrogen and carbon dioxide into methane at 60 °C. The two reactors used for methane production were stirred-tank reactor (ST) and a bubble column reactor (BC), which were selected because they can provide a good comparison between the medium agitation type and gas–liquid mass transfer. The specific growth rate of KEPCO-1 in the ST and BC was 0.03 h−1 and 0.07 h−1, respectively. The methane conversion rate increased to 77.8 L/L/d in the ST and 19.8 L/L/d in the BC. To prevent the dilution of nutrients in the medium by the water generated during the hydrogenotrophic methanation reaction, a membrane distillation (MD) process was applied to selectively remove water from the culture medium. The MD process selectively removed only water from the medium. Fouling by KEPCO-1 had a negligible effect on flux and showed a high removal performance flux of 16.3 ± 3.1 L/m2/h. By operating the MD process in conjunction with the hydrogenotrophic methanation process, it is possible to prevent the dilution of the nutrients in the medium by the water generated during the methanation process, thereby maintaining stable microbial growth and methanation activity.

Treatment of Liquid By-Products of Hydrothermal Carbonization (HTC) of Agricultural Digestate Using Membrane Separation

“…This introduces significant water loss through evaporation. Few studies have been conducted so far, aiming at the recovery of water from anaerobic digestion (AD) using membranes [8].…”

Carbon Capture and Utilization Technology Development Opportunities Based on Biomethanation

“…The VVD mean (41.34 L L −1 day −1 ) was limited by the volume of the gas bag, buffer storage of the off-gas, which is led into the gas analyzer. Despite this limitation, the VVD value is considered adequate comparing to other lab-scale experiments [55].…”

Complete Genome Sequence of Methanothermobacter sp. Strain THM-1, a Thermophilic and Hydrogenotrophic Methanogen Isolated from an Anaerobic Reactor in South Korea

“…Less than 10 μl of the reactor sample was injected into 50 ml of basic anaerobic agar (1.5% [wt/vol] agar added to basic anaerobic medium [ 2 ]) reinforced with sodium bicarbonate. The agar solidified after homogenization at approximately 60°C ( 3 , 4 ). The anaerobic agar medium containing the bacteria was incubated at 60°C under atmospheric conditions that included CO 2 and H 2 at a ratio of 1:4.…”