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Author |
Hulatt, C.J.; Thomas, D.N. |
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Title |
Energy efficiency of an outdoor microalgal photobioreactor sited at mid-temperate latitude |
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Journal Article |
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Year  |
2011 |
Publication |
Bioresource Technology |
Abbreviated Journal |
Bioresour Technol |
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Volume |
102 |
Issue |
12 |
Pages |
6687-6695 |
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Keywords |
Biomass; *Bioreactors; Climate; Geography; Microalgae/growth & development/*metabolism; Oxygen/metabolism; Scenedesmus/growth & development/*metabolism; Seasons; Solar Energy |
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Abstract |
This work examined the energetic performance of a 6-month semi-continuous cultivation of Scenedesmus obliquus in an outdoor photobioreactor at mid-temperate latitude, without temperature control. By measuring the seasonal biomass production (mean 11.31, range 1.39-23.67 g m(-2)d(-1)), higher heating value (22.94 kJ g(-1)) and solar irradiance, the mean seasonally-averaged photosynthetic efficiency (2.18%) and gross energy productivity (0.27 MJ m(-2) d(-1)) was calculated. When comparing the solar energy conversion efficiency to the energy investment for culture circulation, significant improvements in reactor energy input must be made to make the system viable. Using the data collected to model the energetic performance of a substitute photobioreactor design, we conclude that sustainable photobioreactor cultivation of microalgae in similar temperate climates requires a short light path and low power input, only reasonably obtained by flat-panel systems. However, temperature control was not necessary for effective long-term cultivation. |
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School of Ocean Sciences, College of Natural Sciences, Bangor University, Askew Street, Menai Bridge, Anglesey LL59 5AB, UK. osp418@bangor.ac.uk |
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0960-8524 |
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PMID:21511466 |
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refbase @ user @ |
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12984 |
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Lakaniemi, A.-M.; Hulatt, C.J.; Thomas, D.N.; Tuovinen, O.H.; Puhakka, J.A. |
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Title |
Biogenic hydrogen and methane production from Chlorella vulgaris and Dunaliella tertiolecta biomass |
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Journal Article |
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Year |
2011 |
Publication |
Biotechnology for Biofuels |
Abbreviated Journal |
Biotechnol Biofuels |
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4 |
Issue |
1 |
Pages |
34 |
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Abstract |
BACKGROUND: Microalgae are a promising feedstock for biofuel and bioenergy production due to their high photosynthetic efficiencies, high growth rates and no need for external organic carbon supply. In this study, utilization of Chlorella vulgaris (a fresh water microalga) and Dunaliella tertiolecta (a marine microalga) biomass was tested as a feedstock for anaerobic H2 and CH4 production. RESULTS: Anaerobic serum bottle assays were conducted at 37 degrees C with enrichment cultures derived from municipal anaerobic digester sludge. Low levels of H2 were produced by anaerobic enrichment cultures, but H2 was subsequently consumed even in the presence of 2-bromoethanesulfonic acid, an inhibitor of methanogens. Without inoculation, algal biomass still produced H2 due to the activities of satellite bacteria associated with algal cultures. CH4 was produced from both types of biomass with anaerobic enrichments. Polymerase chain reaction-denaturing gradient gel electrophoresis profiling indicated the presence of H2-producing and H2-consuming bacteria in the anaerobic enrichment cultures and the presence of H2-producing bacteria among the satellite bacteria in both sources of algal biomass. CONCLUSIONS: H2 production by the satellite bacteria was comparable from D. tertiolecta (12.6 ml H2/g volatile solids (VS)) and from C. vulgaris (10.8 ml H2/g VS), whereas CH4 production was significantly higher from C. vulgaris (286 ml/g VS) than from D. tertiolecta (24 ml/g VS). The high salinity of the D. tertiolecta slurry, prohibitive to methanogens, was the probable reason for lower CH4 production. |
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Department of Chemistry and Bioengineering, Tampere University of Technology, PO Box 541, FI-33101 Tampere, Finland. aino-maija.lakaniemi@tut.fi |
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1754-6834 |
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PMID:21943287; PMCID:PMC3193024 |
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refbase @ user @ |
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12985 |
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Hulatt, C.J.; Thomas, D.N. |
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Title |
Dissolved organic matter (DOM) in microalgal photobioreactors: a potential loss in solar energy conversion? |
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Journal Article |
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Year |
2010 |
Publication |
Bioresource Technology |
Abbreviated Journal |
Bioresour Technol |
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101 |
Issue |
22 |
Pages |
8690-8697 |
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Keywords |
Bioreactors/*microbiology; Chlorella vulgaris/*physiology; Culture Media/chemistry; *Electric Power Supplies; Energy Transfer; Organic Chemicals/*chemistry/*metabolism; Photochemistry/*instrumentation; Solubility |
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Microalgae are considered to be a potential alternative to terrestrial crops for bio-energy production due to their relatively high productivity per unit area of land. In this work we examined the amount of dissolved organic matter exuded by algal cells cultured in photobioreactors, to examine whether a significant fraction of the photoassimilated biomass could potentially be lost from the harvestable biomass. We found that the mean maximum amount of dissolved organic carbon (DOC) released measured 6.4% and 17.3% of the total organic carbon in cultures of Chlorellavulgaris and Dunaliella tertiolecta, respectively. This DOM in turn supported a significant growth of bacterial biomass, representing a further loss of the algal assimilated carbon. The release of these levels of DOC indicates that a significant fraction of the photosynthetically fixed organic matter could be lost into the surrounding water, suggesting that the actual biomass yield per hectare for industrial purposes could be somewhat less than expected. A simple and inexpensive optical technique, based on chromophoric dissolved organic matter (CDOM) measurements, to monitor such losses in commercial PBRs is discussed. |
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School of Ocean Sciences, College of Natural Sciences, Bangor University, Menai Bridge, Anglesey, UK. osp418@bangor.ac.uk |
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0960-8524 |
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PMID:20634058 |
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refbase @ user @ |
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12981 |
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Stedmon, C.A.; Thomas, D.N.; Granskog, M.; Kaartokallio, H.; Papadimitriou, S.; Kuosa, H. |
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Characteristics of dissolved organic matter in Baltic coastal sea ice: allochthonous or autochthonous origins? |
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Journal Article |
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Year |
2007 |
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Environmental Science & Technology |
Abbreviated Journal |
Environ Sci Technol |
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41 |
Issue |
21 |
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7273-7279 |
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Carbon/analysis; *Humic Substances; Ice Cover/*chemistry; Nitrogen/analysis; Oceans and Seas; Spectrometry, Fluorescence |
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The origin of dissolved organic matter (DOM) within sea ice in coastal waters of the Baltic Sea was investigated using parallel factor (PARAFAC) analysis of DOM fluorescence. Sea ice DOM had distinctly different fluorescence characteristics than that of the underlying humic-rich waters and was dominated by protein-like fluorescence signals. PARAFAC analysis identified five fluorescent components, all of which were present in both sea ice and water. Three humic components were negatively correlated to salinity and concluded to be terrestrially derived material. Baltic Sea ice DOM was found to be a mixture of humic material from the underlying water column incorporated during ice formation and autochthonous material produced by organisms within the ice. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations were correlated to the humic fluorescence, indicating that the majority of the organic carbon and nitrogen in Baltic Sea ice is bound in terrestrial humic material trapped within the ice. This has implications for our understanding of sea ice carbon cycling in regions influenced by riverine input (e.g., Baltic and Arctic coastal waters), as the susceptibility of DOM to degradation and remineralization is largely determined by its source. |
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Department of Marine Ecology, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, 4000 Roskilde, Denmark. cst@dmu.dk |
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0013-936X |
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PMID:18044499 |
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refbase @ user @ |
Serial |
12979 |
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Author |
Granskog, M.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Vainio, J. |
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Title |
Sea ice in the Baltic Sea – A review |
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Journal Article |
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Year |
2006 |
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Estuarine, Coastal and Shelf Science |
Abbreviated Journal |
Estuar Coast Shelf Sci |
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70 |
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1-2 |
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145-160 |
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sea ice; Baltic Sea; biogeochemistry; plankton; seasons |
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Although the seasonal ice cover of the Baltic Sea has many similarities to its oceanic counterpart in Polar Seas and Oceans, there are many unique characteristics that mainly result from the brackish waters from which the ice is formed, resulting in low bulk salinities and porosities. In addition, due to the milder climate than Polar regions, the annual maximum ice extent is highly variable, and rain and freeze-melt cycles can occur throughout winter. Up to 35% of the sea ice mass can be composed from metamorphic snow, rather than frozen seawater, and in places snow and superimposed ice can make up to 50% of the total ice thickness. There is pronounced atmospheric deposition of inorganic nutrients and heavy metals onto the ice, and in the Bothnian Bay it is estimated that 5% of the total annual flux of nitrogen and phosphorus and 20–40% of lead and cadmium may be deposited onto the ice fields from the atmosphere. It is yet unclear whether or not the ice is simply a passive store for atmospherically deposited compounds, or if they are transformed through photochemical processes or biological accumulation before released at ice and snow melt.As in Polar sea ice, the Baltic ice can harbour rich biological assemblages, both within the ice itself, and on the peripheries of the ice at the ice/water interface. Much progress has been made in recent years to study the composition of these assemblages as well as measuring biogeochemical processes within the ice related to those in underlying waters. The high dissolved organic matter loading of Baltic waters and ice result in the ice having quite different chemical characteristics than those known from Polar Oceans. The high dissolved organic material load is also responsible in large degree to shape the optical properties of Baltic Sea ice, with high absorption of solar radiation at shorter wavelengths, a prerequisite for active photochemistry of dissolved organic matter.Land-fast ice in the Baltic also greatly alters the mixing characteristics of river waters flowing into coastal waters. River plumes extend under the ice to a much greater distance, and with greater stability than in ice-free conditions. Under-ice plumes not only alter the mixing properties of the waters, but also result in changed ice growth dynamics, and ice biological assemblages, with the underside of the ice being encased, in the extreme case, with a frozen freshwater layer.There is a pronounced gradient in ice types from more saline ice in the south to freshwater ice in the north. The former is characteristically more porous and supports more ice-associated biology than the latter. Ice conditions also vary considerably in different parts of the Baltic Sea, with ice persisting for over half a year in the northernmost part of the Baltic Sea, the Bothnian Bay. In the southern Baltic Sea, ice appears only during severe winters. |
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Granskog: Arctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland |
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Elsevier Science BV |
Place of Publication |
Amsterdam |
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0272-7714 |
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Baltic Sea |
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Call Number |
refbase @ admin @ Granskog++2006 |
Serial |
738 |
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