Optimizing CO2 transfer in algal open ponds

Caia, Margaux; Bernard, Olivier; Béchet, Quentin

doi:10.1016/j.algal.2018.09.009

Cited by 18 publications

(6 citation statements)

References 40 publications

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“…CO 2 is a raw material for microalgal photosynthesis, and thus concentrations of CO 2 affect microalgal growth . Accordingly, high CO 2 utilization is a prerequisite for the production of large amounts of microalgal biomass. , As shown in Figure D, the CO 2 utilization efficiency was dramatically increased in the presence of 1 μM rac -GR24, suggesting that the enhanced CO 2 utilization efficiency maximized the input of CO 2 for photosynthesis during cultivation . RuBisCO and carbonic anhydrase are the key enzymes involved in photosynthesis and carbon fixation and are thus responsible for the capture of environmental CO 2 to support microalgal growth .…”

Section: Resultsmentioning

confidence: 96%

“…34,35 As shown in Figure 1D, the CO 2 utilization efficiency was dramatically increased in the presence of 1 μM rac-GR24, suggesting that the enhanced CO 2 utilization efficiency maximized the input of CO 2 for photosynthesis during cultivation. 36 RuBisCO and carbonic anhydrase are the key enzymes involved in photosynthesis and carbon fixation and are thus responsible for the capture of environmental CO 2 to support microalgal growth. 37 Higher RuBisCO activity was recorded during the macrozooid stage, which is attributable to the addition of 1 μM rac-GR24 (Figure 1E).…”

Section: Rac-gr24mentioning

confidence: 99%

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Supplementation with rac-GR24 Facilitates the Accumulation of Biomass and Astaxanthin in Two Successive Stages of Haematococcus pluvialis Cultivation

Wang

Mou

Qin

et al. 2022

J. Agric. Food Chem.

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The unicellular freshwater green alga Haematococcus pluvialis has attracted much research attention due to its biosynthetic ability for large amounts of astaxanthin, a blood-red ketocarotenoid that is used in cosmetics, nutraceuticals, and pharmaceuticals. Recently, numerous studies have investigated the functions of natural astaxanthin; however, the high cost of the production of astaxanthin from H. pluvialis cultures restricts its commercial viability. There is an urgent need to fulfill commercial demands by increasing astaxanthin accumulation from H. pluvialis cultures. In this study, we discovered that treatment of H. pluvialis cultures at the beginning of the macrozooid stage (day 0) with 1 μM rac-GR24, a synthetic analogue of strigolactones (a class of phytohormones), led to significant increases in biomass [up to a maximum dry cell weight (DCW) of 0.53 g/L] during the macrozooid stage and astaxanthin (from 0.63 to 5.32% of DCW) during the hematocyst stage. We elucidated that this enhancement of biomass accumulation during the macrozooid stage by rac-GR24 is due to its increasing CO 2 utilization efficiency in photosynthesis and carbohydrate biosynthesis. We also found that rac-GR24 stimulated the overproduction of nicotinamide adenine dinucleotide phosphate (NADPH) and antioxidant enzymes in H. pluvialis cultures, which alleviated the oxidative damage caused by reactive oxygen species generated during the hematocyst stage due to the exhaustion of nitrogen supplies. Moreover, rac-GR24 treatment of H. pluvialis synergistically altered the activity of the pathways of fatty acid biosynthesis and astaxanthin esterification, which resulted in larger amounts of astaxanthin being generated by rac-GR24-treated cultures than by controls. In summary, we have developed a feasible and economic rac-GR24-assisted strategy that increases the amounts of biomass and astaxanthin generated by H. pluvialis cultures, and have provided novel insights into the mechanistic roles of rac-GR24 to achieve these effects.

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Section: Resultsmentioning

confidence: 96%

Section: Rac-gr24mentioning

confidence: 99%

Supplementation with rac-GR24 Facilitates the Accumulation of Biomass and Astaxanthin in Two Successive Stages of Haematococcus pluvialis Cultivation

Wang

Mou

Qin

et al. 2022

J. Agric. Food Chem.

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“…NH3, CO2 and O2), also influencing pH, and consequently the biological process rates and dissociation equilibria. It was therefore calibrated, with the resulting value falling in the literature range (Mendoza et al, 2013;Caia et al, 2018).…”

Section: Sensitivity Analysis and Parameter Estimationmentioning

confidence: 99%

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

et al. 2021

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This paper proposes a new model describing the algae-bacteria ecosystem evolution in an outdoor raceway for wastewater treatment. The ALBA model is based on a mass balance of COD, C, N and P, but also H and O. It describes growth and interactions among algae, heterotrophic and nitrifying bacteria, while local climate drives light and temperature. Relevant chemical/physical processes are also included. The minimum-law was used as ground principle to describe the multi-limitation kinetics. The model was setup and calibrated with an original data set recorded on a 56 m 2 raceway located in the South of France, continuously treating synthetic wastewater. The main process variables were daily measured along 443 days of operations and dissolved O2 and pH were on-line recorded. A sub-dataset was used for calibration and the model was successfully validated, along the different seasons over a period of 414 days. The model proved to be effective in reproducing both the short term nycthemeral dynamics and the long-term seasonal ones. The analysis of different scenarios reveals the fate of nitrogen and the key role played by oxygen and CO2 in the interactions between the different players of the ecosystem. On average, the process turns out to be CO2 neutral, as compared to a standard activated sludge where approximately half of the influent carbon will end up in the atmosphere. The ALBA model revealed that a suboptimal regulation of the paddle wheel can bring to several detrimental impacts. At high velocity, the strong aeration will reduce the available oxygen provided by photo-oxygenation, while without aeration, it can rapidly lead to oxygen inhibition of the photosynthetic process. On the other hand, during night, the paddle wheel is fundamental to ensure enough oxygen in the system to support algal-bacteria metabolism. The model can be used to support advanced control strategies, including smart regulation of the paddle wheel velocity to more efficiently balance the mixing, aeration and degassing effects.

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“…Culturing microalgae at lower temperatures than optimum will affect photosynthesis as carbon assimilation activity is reduced while overheating degrades photosynthetic proteins which lowers photosynthetic rates and thereby shrinks microalgae cells ( Anjos et al, 2013 ). Optimal temperatures for most microalgae species range between 20 and 35°C ( Xu et al, 2010 ; Cho et al, 2011 ) but certain thermophilic species such as Anacystis nidulans can tolerate up to 40°C ( Caïa et al, 2018 ).…”

Section: Optimization Of Microalgal Growth Conditionsmentioning

confidence: 99%

“…The sparger injects CO 2 in gas bubbles at the bottom of the pond while a paddlewheel circulates CO 2 throughout the microalgae culture ( Cheng et al, 2015a ). By studying CO 2 transfer rates in an open algal pond, it was found that decelerating the paddle wheel rotation speed to 13 rpm decreases CO 2 and losses up to 61% ( Caïa et al, 2018 ). Additionally, to achieve the maximum CO 2 utilization efficiency, CO 2 must be extracted from gas bubbles before the bubbles escape to the pond surface.…”

Section: Optimization Of Microalgal Growth Conditionsmentioning

confidence: 99%

Microalgal Biomass as Feedstock for Bacterial Production of PHA: Advances and Future Prospects

Tan

Nadir

Sudesh

2022

Front. Bioeng. Biotechnol.

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The search for biodegradable plastics has become the focus in combating the global plastic pollution crisis. Polyhydroxyalkanoates (PHAs) are renewable substitutes to petroleum-based plastics with the ability to completely mineralize in soil, compost, and marine environments. The preferred choice of PHA synthesis is from bacteria or archaea. However, microbial production of PHAs faces a major drawback due to high production costs attributed to the high price of organic substrates as compared to synthetic plastics. As such, microalgal biomass presents a low-cost solution as feedstock for PHA synthesis. Photoautotrophic microalgae are ubiquitous in our ecosystem and thrive from utilizing easily accessible light, carbon dioxide and inorganic nutrients. Biomass production from microalgae offers advantages that include high yields, effective carbon dioxide capture, efficient treatment of effluents and the usage of infertile land. Nevertheless, the success of large-scale PHA synthesis using microalgal biomass faces constraints that encompass the entire flow of the microalgal biomass production, i.e., from molecular aspects of the microalgae to cultivation conditions to harvesting and drying microalgal biomass along with the conversion of the biomass into PHA. This review discusses approaches such as optimization of growth conditions, improvement of the microalgal biomass manufacturing technologies as well as the genetic engineering of both microalgae and PHA-producing bacteria with the purpose of refining PHA production from microalgal biomass.

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Optimizing CO2 transfer in algal open ponds

Cited by 18 publications

References 40 publications

Supplementation with rac-GR24 Facilitates the Accumulation of Biomass and Astaxanthin in Two Successive Stages of Haematococcus pluvialis Cultivation

Supplementation with rac-GR24 Facilitates the Accumulation of Biomass and Astaxanthin in Two Successive Stages of Haematococcus pluvialis Cultivation

ALBA: A comprehensive growth model to optimize algae-bacteria wastewater treatment in raceway ponds

Microalgal Biomass as Feedstock for Bacterial Production of PHA: Advances and Future Prospects

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