Effect of pH Change on the Microalgae-Based Biogas Upgrading Process
An alternative way to remove CO<sub>2</sub> from biogas is the use of photosynthetic microorganisms, such as microalgae. This can be achieved by the operation of an open photobioreactor, connected with a mass transfer column, such as a counterflow column. This technology provides up-grad...
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MDPI AG
2022-11-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/12/23/12194 |
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| author | Leslie Meier Carlos Vilchez María Cuaresma Álvaro Torres-Aravena David Jeison |
| author_facet | Leslie Meier Carlos Vilchez María Cuaresma Álvaro Torres-Aravena David Jeison |
| author_sort | Leslie Meier |
| collection | DOAJ |
| description | An alternative way to remove CO<sub>2</sub> from biogas is the use of photosynthetic microorganisms, such as microalgae. This can be achieved by the operation of an open photobioreactor, connected with a mass transfer column, such as a counterflow column. This technology provides up-graded biogas with high quality. The microalgal uptake of CO<sub>2</sub> from the biogas in counterflow columns generates pH changes in microalgae culture. To clarify the potential effect of these dynamic pH conditions in the culture, the effect of pH change on the photosynthetic activity and PSII quantum yield was studied for microalgae <i>Chlorella sorokiniana</i>. Thus, assays were carried out, where the pH drop reported in the counterflow columns was replicated in batch microalgae culture through HCl addition and CO<sub>2</sub> injection, moving the culture pH from 7.0 to 5.0 and from 7.0 to 5.8, respectively. Moreover, the effect of light/darkness on photosynthetic activity was tested when the pH decreased. The results obtained in this research showed that the photosynthetic activity decreased for the light conditions when the pH was shifted by HCl addition and CO<sub>2</sub> injection. Despite this, the value of the PSII quantum yield remained at 0.6–0.7, which means that the microalgae culture did not suffer a negative effect on the photosynthetic system of cells because a high value of PSII efficiency remained. In the same way, the results indicated that when the pH change was corrected, the photosynthetic activity recovered. Moreover, the apparent affinity constant for dissolved inorganic carbon (KDIC) was 0.9 µM at pH 5 and 112.0 µM at pH 7, which suggests that the preferred carbon source for <i>C.sorokniana</i> is CO<sub>2</sub>. Finally, all the results obtained indicated that the pH drop in the counter-flow column for biogas upgrading did not cause permanent damage to the photosynthetic system, and the decrease in the photosynthetic activity as a result of the pH drop can be recovered when the pH is corrected. |
| first_indexed | 2024-03-09T17:53:14Z |
| format | Article |
| id | doaj.art-61bcebf60be54d84a821e9681fdff119 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-09T17:53:14Z |
| publishDate | 2022-11-01 |
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| spelling | doaj.art-61bcebf60be54d84a821e9681fdff1192023-11-24T10:32:31ZengMDPI AGApplied Sciences2076-34172022-11-0112231219410.3390/app122312194Effect of pH Change on the Microalgae-Based Biogas Upgrading ProcessLeslie Meier0Carlos Vilchez1María Cuaresma2Álvaro Torres-Aravena3David Jeison4Department of Chemical Engineering, Universidad de La Frontera, Av. Francisco Salazar, Temuco 01145, ChileAlgal Biotechnology Group, CIDERTA and Faculty of Experimental Sciences, University of Huelva, Huelva Business Park, 21007 Huelva, SpainAlgal Biotechnology Group, CIDERTA and Faculty of Experimental Sciences, University of Huelva, Huelva Business Park, 21007 Huelva, SpainEscuela de Ingeniería Bioquímica, Facultad de Ingeniería, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Valparaíso 2950, ChileEscuela de Ingeniería Bioquímica, Facultad de Ingeniería, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Valparaíso 2950, ChileAn alternative way to remove CO<sub>2</sub> from biogas is the use of photosynthetic microorganisms, such as microalgae. This can be achieved by the operation of an open photobioreactor, connected with a mass transfer column, such as a counterflow column. This technology provides up-graded biogas with high quality. The microalgal uptake of CO<sub>2</sub> from the biogas in counterflow columns generates pH changes in microalgae culture. To clarify the potential effect of these dynamic pH conditions in the culture, the effect of pH change on the photosynthetic activity and PSII quantum yield was studied for microalgae <i>Chlorella sorokiniana</i>. Thus, assays were carried out, where the pH drop reported in the counterflow columns was replicated in batch microalgae culture through HCl addition and CO<sub>2</sub> injection, moving the culture pH from 7.0 to 5.0 and from 7.0 to 5.8, respectively. Moreover, the effect of light/darkness on photosynthetic activity was tested when the pH decreased. The results obtained in this research showed that the photosynthetic activity decreased for the light conditions when the pH was shifted by HCl addition and CO<sub>2</sub> injection. Despite this, the value of the PSII quantum yield remained at 0.6–0.7, which means that the microalgae culture did not suffer a negative effect on the photosynthetic system of cells because a high value of PSII efficiency remained. In the same way, the results indicated that when the pH change was corrected, the photosynthetic activity recovered. Moreover, the apparent affinity constant for dissolved inorganic carbon (KDIC) was 0.9 µM at pH 5 and 112.0 µM at pH 7, which suggests that the preferred carbon source for <i>C.sorokniana</i> is CO<sub>2</sub>. Finally, all the results obtained indicated that the pH drop in the counter-flow column for biogas upgrading did not cause permanent damage to the photosynthetic system, and the decrease in the photosynthetic activity as a result of the pH drop can be recovered when the pH is corrected.https://www.mdpi.com/2076-3417/12/23/12194biogas upgradingmicroalgaecarbon sequestrationpH |
| spellingShingle | Leslie Meier Carlos Vilchez María Cuaresma Álvaro Torres-Aravena David Jeison Effect of pH Change on the Microalgae-Based Biogas Upgrading Process Applied Sciences biogas upgrading microalgae carbon sequestration pH |
| title | Effect of pH Change on the Microalgae-Based Biogas Upgrading Process |
| title_full | Effect of pH Change on the Microalgae-Based Biogas Upgrading Process |
| title_fullStr | Effect of pH Change on the Microalgae-Based Biogas Upgrading Process |
| title_full_unstemmed | Effect of pH Change on the Microalgae-Based Biogas Upgrading Process |
| title_short | Effect of pH Change on the Microalgae-Based Biogas Upgrading Process |
| title_sort | effect of ph change on the microalgae based biogas upgrading process |
| topic | biogas upgrading microalgae carbon sequestration pH |
| url | https://www.mdpi.com/2076-3417/12/23/12194 |
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