Name: ADRIANO GOLDNER COSTA
Type: PhD thesis
Publication date: 29/03/2018
Advisor:
Name |
Role |
|---|---|
| Valéria de Oliveira Fernandes | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Camilla Rozindo Dias Milanez | Internal Alternate * |
| Camilo Dias Júnior | Internal Examiner * |
| Gustavo Haddad Souza Vieira | External Alternate * |
| Maria do Carmo Pimentel Batitucci | Internal Examiner * |
| Paola Alfonsa Vieira Lo Monaco | External Examiner * |
| Stéfano Zorzal de Almeida | External Examiner * |
| Valéria de Oliveira Fernandes | Advisor * |
Summary: The growing interest in microalgae cultivation is due not only to its environmental
and biological importance, but also because it constitutes an important tool for the
production of biomass with several applications of economic interest, such as the
production of biocomposites for human food supplementation, feed production and
other potential applications such as wastewater treatment and biofuel production.
Studies with the manipulation of the cultivation conditions, such as light and
temperature, are important to evaluate the development of microalgae and to make
feasible the increase of biomass, subsidizing the reduction of costs in its production.
In addition, the use of readily available alternative media that are rich in nutritional
compounds, such as agricultural effluent, can help to make the process viable on a
larger scale. In this study, the effects of different temperature conditions (25ºC, 30ºC
and 35ºC) and luminosity (without shading, 50% shading and 70% shading) on the
growth and biomass of the Desmodesmus communis species were evaluated, as
well as different concentrations of effluents (residual hydroponic solution of lettuce
cultivation and biodigested swine residue) as alternative means in the cultivation of
Scenedesmus acuminatus, aiming to minimize productive costs and mitigate
environmental impacts. For the residual hydroponic solution, three treatments with
different concentrations of the effluent (20%, 30% and 40%) and a control with
ASM1 synthetic culture medium were established; for the biodigested swine residue,
three treatments with different effluent concentrations (10%, 15% and 20%) and a
control with ASM1 culture medium. In the experiment with different temperatures,
higher cell densities were recorded at 30°C and 35°C, but the accumulation of dry
mass and chlorophyll was significantly higher at 30°C. As for luminosity, the
condition without shading and 50% shading presented approximate values of growth
parameters. Higher chlorophyll concentration was recorded in the 50% treatment.
Algae grown under 70% shading had significant limitations on growth, biomass and
chlorophyll production. In the experiments with different concentrations of
agricultural effluents, in addition to the growth evaluation, the differences in the
chemical composition (carbohydrates, proteins, lipids and methyl esters of fatty
acids) of the biomass generated, as well as their potential in terms of nutrient
removal were analyzed. It was concluded that intermediate levels of temperature
and luminosity presented more promising results to be used in the cultivation of D.
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communis, in order to obtain compounds of commercial interest. As for the different
concentrations of agricultural effluents tested as alternative culture media, the
cultivation of S. acuminatus in residual hydroponic solution presented an interesting
proposal, since the algae used presented a high growth in the highest tested
concentrations of this effluent, besides great potential to remove inorganic
wastewater compounds and to produce biomass useful for the production of
biofuels, fertilizers and other bioproducts. On the other hand, the cultivation of
microalgae in swine effluent after biodigestion showed low efficiency in terms of
useful biomass productivity and bioremediation, being unviable to algal growth in
concentrations higher than 10% of the effluent.
Keywords: Biodiesel bioremediation effluents light microalgae temperature
