Dynamic one-dimensional model for biological methanation in a stirred tank reactor

Inkeri, Eero; Tynjälä, Tero; Лаари, Арто; Hyppänen, Timo

doi:10.1016/j.apenergy.2017.10.073

Cited by 19 publications

(27 citation statements)

References 27 publications

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“…However, the low density of H 2 necessitates infrastructure to support its high storage volume. While the direct utilization of H 2 as transport fuel remains under development [5, 10], the infrastructure for large-scale storage and utilization of CH 4 (or natural gas) is already in place [14]. Thus, BBU may become a key technology for the storage of excess renewable electricity in the form of CH 4 .…”

Section: Introductionmentioning

confidence: 99%

Effects of H2:CO2 ratio and H2 supply fluctuation on methane content and microbial community composition during in-situ biological biogas upgrading

Wahid

Mulat

Gaby

et al. 2019

Biotechnol Biofuels

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Background Commercial biogas upgrading facilities are expensive and consume energy. Biological biogas upgrading may serve as a low-cost approach because it can be easily integrated with existing facilities at biogas plants. The microbial communities found in anaerobic digesters typically contain hydrogenotrophic methanogens, which can use hydrogen (H 2 ) as a reducing agent for conversion of carbon dioxide (CO 2 ) into methane (CH 4 ). Thus, biological biogas upgrading through the exogenous addition of H 2 into biogas digesters for the conversion of CO 2 into CH 4 can increase CH 4 yield and lower CO 2 emission. Results The addition of 4 mol of H 2 per mol of CO 2 was optimal for batch biogas reactors and increased the CH 4 content of the biogas from 67 to 94%. The CO 2 content of the biogas was reduced from 33 to 3% and the average residual H 2 content was 3%. At molar H 2 :CO 2 ratios > 4:1, all CO 2 was converted into CH 4 , but the pH increased above 8 due to depletion of CO 2 , which negatively influenced the process stability. Additionally, high residual H 2 content in these reactors was unfavourable, causing volatile fatty acid accumulation and reduced CH 4 yields. The reactor microbial communities shifted in composition over time, which corresponded to changes in the reactor variables. Numerous taxa responded to the H 2 inputs, and in particular the hydrogenotrophic methanogen Methanobacterium increased in abundance with addition of H 2 . In addition, the apparent rapid response of hydrogenotrophic methanogens to intermittent H 2 feeding indicates the suitability of biological methanation for variable H 2 inputs, aligning well with fluctuations in renewable electricity production that may be used to produce H 2 . Conclusions Our research demonstrates that the H 2 :CO 2 ratio has a significant effect on reactor performance during in situ biological methanation. Consequently, the H 2 :CO 2 molar ratio should be kept at 4:1 to avoid process instability. A shift toward hydrogenotrophic methanogenesis was indicated by an increase in the abundance of the obligate hydrogenotrophic methanogen Methanobacterium . ...

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Section: Introductionmentioning

confidence: 99%

Effects of H2:CO2 ratio and H2 supply fluctuation on methane content and microbial community composition during in-situ biological biogas upgrading

Wahid

Mulat

Gaby

et al. 2019

Biotechnol Biofuels

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“…The bio-P2M trickle bed reactor needs energy for operation, estimated to range from 0.1 to 1.0 kWh Nm −3 green gas produced. [8][9][10]52,53 The gas that is formed contains water vapour and is at atmospheric pressure, so it needs to be dried and compressed before injection into the gas grid. Compression is considered part of the "Bio-P2M" transformation block (Figure 1).…”

Section: Methodsmentioning

confidence: 99%

Farm‐scale bio‐power‐to‐methane: Comparative analyses of economic and environmental feasibility

et al. 2019

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Summary Power‐to‐gas technologies are considered to be part of the future energy system, but their viability and applicability need to be assessed. Therefore, models for the viability of farm‐scale bio‐power‐to‐methane supply chains to produce green gas were analysed in terms of levelised cost of energy, energy efficiency and saving of greenhouse gas emission. In bio‐power‐to‐methane, hydrogen from electrolysis driven by surplus renewable electricity and carbon dioxide from biogas are converted to methane by microbes in an ex situ trickle‐bed reactor. Such bio‐methanation could replace the current upgrading of biogas to green gas with membrane technology. Four scenarios were compared: a reference scenario without bio‐methanation (A), bio‐methanation (B), bio‐methanation combined with membrane upgrading (C) and the latter with use of renewable energy only (all‐green; D). The reference scenario (A) has the lowest costs for green gas production, but the bio‐methanation scenarios (B‐D) have higher energy efficiencies and environmental benefits. The higher costs of the bio‐methanation scenarios are largely due to electrolysis, whereas the environmental benefits are due to the use of renewable electricity. Only the all‐green scenario (D) meets the 2026 EU goal of 80% reduction of greenhouse gas emissions, but it would require a CO2 price of 200 € t−1 to achieve the levelised cost of energy of 65 €ct Nm−3 of the reference scenario. Inclusion of the intermittency of renewable energy in the scenarios substantially increases the costs. Further greening of the bio‐methanation supply chain and how intermittency is best taken into account need further investigation.

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“…The volumetric mass transfer coefficient k L a and the gas holdup φ (g) were computed with the empirical equations from Inkeri et al for gassed stirred tank reactors [51], and the ozone gas flow-rate Q (g) was maintained fixed to 2.0 L min −1 . Meanwhile, the ozone concentration at the interphase C * O 3 was a function of the mean logarithmic ozone gas concentration C O 3(g) , according to Equation (29).…”

Section: Mathematical Modelsmentioning

confidence: 99%

Mechanistic Model and Optimization of the Diclofenac Degradation Kinetic for Ozonation Processes Intensification

Acosta-Angulo

Lara-Ramos

Díaz-Angulo

et al. 2021

Water

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This work focused on estimating the rate constants for three ozone-based processes applied in the degradation of diclofenac. The ozonation (Oz) and its intensification with catalysis (COz) and photocatalysis (PCOz) were studied. Three mathematical models were evaluated with a genetic algorithm (GA) to find the optimal values for the kinetics constants. The Theil inequality coefficient (TIC) worked as a criterion to assess the models’ deviation. The diclofenac consumption followed a slow kinetic regime according to the Hatta number (Ha<0.3). However, it strongly contrasted with earlier studies. The obtained values for the volumetric rate of photon absorption (VRPA) corresponding to the PCOz process (1.75×10−6 & 6.54×10−7 Einstein L−1 min−1) were significantly distant from the maximum (2.59×10−5 Einstein L−1 min−1). The computed profiles of chemical species proved that no significant amount of hydroxyl radicals was produced in the Oz, whereas the PCOz achieved the highest production rate. According to this, titanium dioxide significantly contributed to ozone decomposition, especially at low ozone doses. Although the models’ prediction described a good agreement with the experimental data (TIC<0.3), the optimization algorithm was likely to have masked the rate constants as they had highly deviated from already reported values.

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Dynamic one-dimensional model for biological methanation in a stirred tank reactor

Cited by 19 publications

References 27 publications

Effects of H2:CO2 ratio and H2 supply fluctuation on methane content and microbial community composition during in-situ biological biogas upgrading

Effects of H2:CO2 ratio and H2 supply fluctuation on methane content and microbial community composition during in-situ biological biogas upgrading

Farm‐scale bio‐power‐to‐methane: Comparative analyses of economic and environmental feasibility

Mechanistic Model and Optimization of the Diclofenac Degradation Kinetic for Ozonation Processes Intensification

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