Depth optimization of inclined thin layer photobioreactor for efficient microalgae cultivation in high turbidity digestate

Sugarcane ethanol production generates considerable quantities of vinasse, its main wastewater. Microalgae cultivation is a promising option for effluent remediation, since the generated biomass can be feedstock for biofuel and bio-based chemical production. Due to vinasse high turbidity, pretreatment is necessary to clarify this effluent, adapting it as a mixotrophic culture medium. In this context, the present research evaluated the integrated process of electrocoagulation (EC) of sugarcane vinasse with aluminum or iron electrodes and subsequent cultivation of green microalgae Desmodesmus subspicatus. Results indicate pH neutralization and high turbidity removal efficiency by EC with both electrode materials. Aluminum EC and subsequent microalgae cultivation removed 66 and 75% of initial total organic carbon and total nitrogen, respectively, with biomass productivity of 1.45 g L-1day-1 and maximum specific growth rate of 0.095 h-1. Microalgae productivity was inferior in vinasse pretreated by iron EC, suggesting possible interference of ferric compounds in the microalgal development.

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Development of thin-layer cascades for microalgae cultivation: milestones (review)

Folia Microbiologica ◽

10.1007/s12223-019-00739-7 ◽

2019 ◽

Vol 64 (5) ◽

pp. 603-614 ◽

Cited By ~ 8

Author(s):

Tomáš Grivalský ◽

Karolína Ranglová ◽

João A. da Câmara Manoel ◽

Gergely E. Lakatos ◽

Richard Lhotský ◽

...

Keyword(s):

Thin Layer ◽

Microalgae Cultivation

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Advanced Computational Fluid Dynamics Study of the Dissolved Oxygen Concentration within a Thin-Layer Cascade Reactor for Microalgae Cultivation

Energies ◽

10.3390/en14217284 ◽

2021 ◽

Vol 14 (21) ◽

pp. 7284

Author(s):

Karel Petera ◽

Štěpán Papáček ◽

Cristian Inostroza González ◽

José María Fernández-Sevilla ◽

Francisco Gabriel Acién Fernández

Keyword(s):

Fluid Dynamics ◽

Mass Transfer ◽

Computational Fluid Dynamics ◽

Dissolved Oxygen ◽

Thin Layer ◽

Oxygen Evolution ◽

Numerical Study ◽

Numerical Results ◽

Oxygen Distribution ◽

Microalgae Cultivation

High concentration of dissolved oxygen within microalgae cultures reduces the performance of corresponding microalgae cultivation system (MCS). The main aim of this study is to provide a reliable computational fluid dynamics (CFD)-based methodology enabling to simulate two relevant phenomena governing the distribution of dissolved oxygen within MCS: (i) mass transfer through the liquid–air interface and (ii) oxygen evolution due to microalgae photosynthesis including the inhibition by the same dissolved oxygen. On an open thin-layer cascade (TLC) reactor, a benchmark numerical study to assess the oxygen distribution was conducted. While the mass transfer phenomenon is embedded within CFD code ANSYS Fluent, the oxygen evolution rate has to be implemented via user-defined function (UDF). To validate our methodology, experimental data for dissolved oxygen distribution within the 80 meter long open thin-layer cascade reactor are compared against numerical results. Moreover, the consistency of numerical results with theoretical expectations has been shown on the newly derived differential equation describing the balance of dissolved oxygen along the longitudinal direction of TLC. We argue that employing our methodology, the dissolved oxygen distribution within any MCS can be reliably determined in silico, and eventually optimized or/and controlled.

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Applications of Photoelectron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092499 ◽

1976 ◽

Vol 34 ◽

pp. 506-507

Author(s):

William J. Baxter

Keyword(s):

Electron Microscopy ◽

Thermal Decomposition ◽

Chemical Composition ◽

Ultraviolet Radiation ◽

Thin Layer ◽

Edge Effects ◽

Electron Optics ◽

Surface Layers ◽

Crystalline Orientation ◽

Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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