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A control strategy for an intermittently aerated and fed bioreactor to reduce aeration costs: A simulation study. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2021.108081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Villanova V, Singh D, Pagliardini J, Fell D, Le Monnier A, Finazzi G, Poolman M. Boosting Biomass Quantity and Quality by Improved Mixotrophic Culture of the Diatom Phaeodactylum tricornutum. FRONTIERS IN PLANT SCIENCE 2021; 12:642199. [PMID: 33897733 PMCID: PMC8063856 DOI: 10.3389/fpls.2021.642199] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Diatoms are photoautotrophic unicellular algae and are among the most abundant, adaptable, and diverse marine phytoplankton. They are extremely interesting not only for their ecological role but also as potential feedstocks for sustainable biofuels and high-value commodities such as omega fatty acids, because of their capacity to accumulate lipids. However, the cultivation of microalgae on an industrial scale requires higher cell densities and lipid accumulation than those found in nature to make the process economically viable. One of the known ways to induce lipid accumulation in Phaeodactylum tricornutum is nitrogen deprivation, which comes at the expense of growth inhibition and lower cell density. Thus, alternative ways need to be explored to enhance the lipid production as well as biomass density to make them sustainable at industrial scale. In this study, we have used experimental and metabolic modeling approaches to optimize the media composition, in terms of elemental composition, organic and inorganic carbon sources, and light intensity, that boost both biomass quality and quantity of P. tricornutum. Eventually, the optimized conditions were scaled-up to 2 L photobioreactors, where a better system control (temperature, pH, light, aeration/mixing) allowed a further improvement of the biomass capacity of P. tricornutum to 12 g/L.
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Affiliation(s)
- Valeria Villanova
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
- Laboratoire de Physiologie Cellulaire et Végétale, Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS), Commissariat á l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Interdisciplinary Research Institute of Grenoble, CEA Grenoble, Grenoble, France
- Fermentalg SA, Libourne, France
| | - Dipali Singh
- Microbes in the Food Chain, Quadram Institute Biosciences, Norwich Research Park, Norwich, United Kingdom
- Cell System Modelling Group, Oxford Brookes University, Oxford, United Kingdom
| | | | - David Fell
- Cell System Modelling Group, Oxford Brookes University, Oxford, United Kingdom
| | | | - Giovanni Finazzi
- Laboratoire de Physiologie Cellulaire et Végétale, Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS), Commissariat á l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Interdisciplinary Research Institute of Grenoble, CEA Grenoble, Grenoble, France
| | - Mark Poolman
- Cell System Modelling Group, Oxford Brookes University, Oxford, United Kingdom
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Nguyen Quoc B, Wei S, Armenta M, Bucher R, Sukapanpotharam P, Stahl DA, Stensel HD, Winkler MKH. Aerobic granular sludge: Impact of size distribution on nitrification capacity. WATER RESEARCH 2021; 188:116445. [PMID: 33039834 DOI: 10.1016/j.watres.2020.116445] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 09/01/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
The relationship between ammonia oxidation rate, nitrifiers population, and modelled aerobic zone volume in different granule sizes was investigated using aerobic granular sludge from a pilot-scale reactor. The pilot was fed with centrate and secondary effluent amended with acetate as the main carbon source. The maximum specific ammonia oxidation rates and community composition of different aerobic granular sludge size fractions were evaluated by batch tests, quantitative PCR, and genomic analysis. Small (331µm) granules had a 4.72 ± 0.09 times higher maximum specific ammonia oxidizing rate per 1 gVSS, and a 4.05 ± 0.17 times higher specific amoA gene copy number than large (2225µm) granules per 1 gram of wet biomass. However, when related to surface area, small granules had 1.43 ± 0.01 times lower maximum specific ammonia oxidation rate and a 1.66 ± 0.04 times lower specific amoA gene copy number per unit surface than large granules. Experimental results aligned with modeling results in which smaller granules had a higher specific aerobic zone volume to biomass and lower specific aerobic zone volume to surface area. Aerobic granular sludge reactors having the same average diameter of granules may have very different proportions of granule size fractions and hence possess different nitrification rates. Therefore, instead of the commonly reported average granule diameter, a new method was proposed to determine the aerobic volume density per sample, which correlated well with the nitrification rate. This work provides a roadmap to control nitrification capacity by two methods: (a) crushing larger granules into smaller fractions, or (b) increasing the mixed liquor suspended solid concentration to increase the total aerobic zone volume of the system.
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Affiliation(s)
- Bao Nguyen Quoc
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
| | - Stephany Wei
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
| | - Maxwell Armenta
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
| | - Robert Bucher
- Resource Recovery, Wastewater Treatment Division, King County Department of Natural Resources and Parks, WA, USA.
| | - Pardi Sukapanpotharam
- Resource Recovery, Wastewater Treatment Division, King County Department of Natural Resources and Parks, WA, USA.
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
| | - H David Stensel
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
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Ramdani A, Dold P, Gadbois A, Déléris S, Houweling D, Comeau Y. Characterization of the heterotrophic biomass and the endogenous residue of activated sludge. WATER RESEARCH 2012; 46:653-668. [PMID: 22172563 DOI: 10.1016/j.watres.2011.11.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 11/07/2011] [Accepted: 11/09/2011] [Indexed: 05/31/2023]
Abstract
The activated sludge process generates an endogenous residue (X(E)) as a result of heterotrophic biomass decay (X(H)). A literature review yielded limited information on the differences between X(E) and X(H) in terms of chemical composition and content of extracellular polymeric substances (EPS). The objective of this project was to characterize the chemical composition (x, y, z, a, b and c in C(x)H(y)O(z)N(a)P(b)S(c)) of the endogenous and the active fractions and EPS of activated sludge from well designed experiments. To isolate X(H) and X(E) in this study, activated sludge was generated in a 200L pilot-scale aerobic membrane bioreactor (MBR) fed with a soluble and completely biodegradable synthetic influent of sodium acetate as the sole carbon source. This influent, which contained no influent unbiodegradable organic or inorganic particulate matter, allowed the generation of a sludge composed essentially of two fractions: heterotrophic biomass X(H) and an endogenous residue X(E), the nitrifying biomass being negligible. The endogenous decay rate and the active biomass fraction of the MBR sludge were determined in 21-day aerobic digestion batch tests by monitoring the VSS and OUR responses. Fractions of X(H) and X(E) were respectively 68% and 32% in run 1 (MBR at 5.2 day SRT) and 59% and 41% in run 2 (MBR at 10.4 day SRT). The endogenous residue was isolated by subjecting the MBR sludge to prolonged aerobic batch digestion for 3 weeks, and was characterized in terms of (a) elemental analysis for carbon, nitrogen, phosphorus and sulphur; and (b) content of EPS. The MBR sludge was characterized using the same procedures (a and b). Knowing the proportions of X(H) and X(E) in this sludge, it was possible to characterize X(H) by back calculation. Results from this investigation showed that the endogenous residue had a chemical composition different from that of the active biomass with a lower content of inorganic matter (1:4.2), of nitrogen (1:2.9), of phosphorus (1:5.3) and of sulphur (1:3.2) but a similar content of carbon (1:0.98). Based on these elemental analyses, chemical composition formulae for X(H) and X(E) were determined as CH(1.240)O(0.375)N(0.200)P(0.0172)S(0.0070) and CH(1.248)O(0.492)N(0.068)P(0.0032)S(0.0016), respectively. Data from EPS analyses also confirmed this difference in structure between X(E) and X(H) with an EPS content of 11-17% in X(E)versus 26-40% in X(H).
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Affiliation(s)
- Abdellah Ramdani
- Department of Civil, Geological and Mining Engineering, Ecole Polytechnique of Montreal, P.O. Box 6079, Station centre-ville, Montreal, Quebec H3C 3A7, Canada.
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