Innovative operational strategies in photosynthetic biogas upgrading in an outdoors pilot scale algal-bacterial photobioreactor

Marín, David; Carmona-Martínez, Alessandro A.; Blanco, Saúl; Lebrero, Raquel; Muñoz, Raúl

doi:10.1016/j.chemosphere.2020.128470

Cited by 41 publications

(21 citation statements)

References 27 publications

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“…In a more recent study, the CO2 content in the biogas varied between 1.5% and 4.4% at an alkalinity of 1200 mg/L inorganic carbon (IC) and inlet pH between 9.7 and 9.8 (del Rosario Rodero et al, 2020b). In contrast, Marín et al (2021), in a similar experimental range and using a similar setup, reported a much lower CO2 content in biogas of 0.5%. Seasonal variations, Photobioreactor:…”

Section: Need For a Focussed Approach To Photosynthetic Biogas Upgradingmentioning

confidence: 76%

“…This is in contrast to operating conditions of pH above 11 and a temperature above 40 °C, commonly employed for CO2 removal in an alkaline medium without the presence of microalgae (Knuutila et al, 2010). In another example of differentiation between individual components and the integrated system, researchers aimed to achieve a carbon balance in the bubble column-photobioreactor system by fixing algal productivity (Marín et al, 2021). The controlled values varying between 7.5-15 g/m 2 /d were much lower than the achievable productivity of 20-25 g/m 2 /d in open pond systems (Sun et al, 2016).…”

Section: Need For a Focussed Approach To Photosynthetic Biogas Upgradingmentioning

confidence: 99%

“…The corresponding algal concentrations generated would vary between 2.8 gDW/L and 0.35 gDW/L, respectively. Sufficient year-round CO2 uptake could be ensured by temperature-controlled microalgae cultivation, either in closed photobioreactors (Bose et al, 2019) or open ponds within greenhouses (Marín et al, 2021). A higher algal concentration is always desired, as it greatly simplifies the harvesting system design and cost.…”

Section: On the Operation Of Algae Cultivation And Harvesting Systemmentioning

confidence: 99%

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A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

et al. 2021

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Studies attempting to optimise photosynthetic biogas upgrading by simultaneous investigation of the bubble column-photobioreactor setup have experienced considerable variability in results and conclusions. To identify the sources of such variation, this work quantitatively compared seven design factors (superficial gas velocity; liquid to gas flow rate (L/G) ratio; empty bed residence time; liquid inlet pH; liquid inlet alkalinity; temperature; and algal concentration) using the L16 Taguchi orthogonal array as a screening design of experiment. Assessments were performed using the signal to noise (S/N) ratio on the performance of CO2 removal (CO2 removal efficiency, CO2 absorption rate, and overall CO2 mass transfer coefficient) and O2 stripping (O2 concentration in biomethane and O2 flow rate in biomethane). Results showed that pH and L/G ratio were the most critical design factors. Temperature and gas residence times had minimal impact on the biomethane composition. The interactive effect between pH and L/G ratio was the most impactful, followed by the interactive effects between superficial gas velocity and L/G ratio and pH on CO2 removal efficiency. The impact of L/G ratio, algal concentration, and pH (in that order of impact) caused up to a 90% variation in oxygen content in biomethane. However, algal concentration had a diminishing role as the L/G ratio increased. Using only the statistically significant main effects and interactions, the biomethane composition (CO2% and O2%) was predicted with over 95% confidence through regression equations for superficial gas velocity up to 0.2 cm/s.

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Section: Need For a Focussed Approach To Photosynthetic Biogas Upgradingmentioning

confidence: 76%

Section: Need For a Focussed Approach To Photosynthetic Biogas Upgradingmentioning

confidence: 99%

Section: On the Operation Of Algae Cultivation And Harvesting Systemmentioning

confidence: 99%

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A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

et al. 2021

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“…The major technology bottlenecks identified are [140]: (i) the need to operate at high alkalinity without external addition of chemicals, (ii) poor performance under cold climate conditions, (iii) high solid content and turbidity of digestates and (iv) a poor microalgae settleability hindering biomass productivity control.…”

Section: Photosynthetic Biogas Upgradingmentioning

confidence: 99%

Biogas from Anaerobic Digestion as an Energy Vector: Current Upgrading Development

Iglesias¹,

Muñoz

Fdz-Polanco

et al. 2021

Energies

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The present work reviews the role of biogas as advanced biofuel in the renewable energy system, summarizing the main raw materials used for biogas production and the most common technologies for biogas upgrading and delving into emerging biological methanation processes. In addition, it provides a description of current European legislative framework and the potential biomethane business models as well as the main biogas production issues to be addressed to fully deploy these upgrading technologies. Biomethane could be competitive due to negative or zero waste feedstock prices, and competitive to fossil fuels in the transport sector and power generation if upgrading technologies become cheaper and environmentally sustainable.

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“…The maximum biomethane concentration of 90% was limited by desorption of N 2 and O 2 . Finally, Marin et al [36] used an absorption unit in which gas and liquid flows were co-current (L/G ratio of 0.5). These authors used various operating strategies: with no aeration of the photobioreactor, the CO 2 concentration of purified biogas was up to 6.1% and the pH was 9.1, whereas with aeration (1 vvm), they obtained a biogas CO 2 concentration of 0.3-0.4% and pH of 9.8.…”

Section: Effect Of Flow Mode In the Absorption Columnmentioning

confidence: 99%

Influence of Leachate and Nitrifying Bacteria on Photosynthetic Biogas Upgrading in a Two-Stage System

et al. 2021

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Photosynthetic biogas upgrading using two-stage systems allows the absorption of carbon dioxide (CO2) in an absorption unit and its subsequent assimilation by microalgae. The production of microalgae requires large amounts of nutrients, thus making scale-up difficult and reducing economic feasibility. The photosynthetic process produces oxygen (O2) (1 mol per mol of CO2 consumed), which can be desorbed into purified biogas. Two-stage systems reduce its impact but do not eliminate it. In this study, we test the use of landfill leachate as a nutrient source and propose a viable and economical strategy for reducing the O2 concentration. First, the liquid/gas (L/G) ratio and flow mode of the absorber were optimized for 20% and 40% CO2 with COMBO medium, then landfill leachate was used as a nutrient source. Finally, the system was inoculated with nitrifying bacteria. Leachate was found to be suitable as a nutrient source and to result in a significant improvement in CO2 absorption, with outlet concentrations of 0.01% and 0.6% for 20% and 40% CO2, respectively, being obtained. The use of nitrifying bacteria allowed a reduction in dissolved oxygen (DO) concentration, although it also resulted in a lower pH, thus making CO2 uptake slightly more difficult.

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Innovative operational strategies in photosynthetic biogas upgrading in an outdoors pilot scale algal-bacterial photobioreactor

Cited by 41 publications

References 27 publications

A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

Biogas from Anaerobic Digestion as an Energy Vector: Current Upgrading Development

Influence of Leachate and Nitrifying Bacteria on Photosynthetic Biogas Upgrading in a Two-Stage System

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