Microalgae harvesting using flocculation and dissolved air flotation: Selecting the right vessel for lab-scale experiments

Rao, N.R.H.; Beyer, V.P.; Henderson, Rita K.; Thielemans, Wim; Muylaert, Koenraad

doi:10.1016/j.biortech.2023.128786

Cited by 15 publications

(3 citation statements)

References 43 publications

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“…Flotation experiments were performed in a Platypus DAF jar tester (Aquagenics Pty Ltd., Australia), following a procedure described in ref . In summary, 1 L of cells at midexponential growth phase, with an initial OD 750 of 1, was added to test jars.…”

Section: Methodsmentioning

confidence: 99%

The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

Demir-Yilmaz,

Pappa,

Lama

et al. 2024

ACS Appl. Bio Mater.

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Microalgae show great promise for producing valuable molecules like biofuels, but their large-scale production faces challenges, with harvesting being particularly expensive due to their low concentration in water, necessitating extensive treatment. While methods such as centrifugation and filtration have been proposed, their efficiency and cost-effectiveness are limited. Flotation, involving air-bubbles lifting microalgae to the surface, offers a viable alternative, yet the repulsive interaction between bubbles and cells can hinder its effectiveness. Previous research from our group proposed using an amphiphilic chitosan derivative, polyoctyl chitosan (PO-chitosan), to functionalize bubbles used in dissolved air flotation (DAF). Molecular-scale studies performed using atomic force microscopy (AFM) revealed that PO-chitosan's efficiency correlates with cell surface properties, particularly hydrophobic ones, raising the question of whether this molecule can in fact be used more generally to harvest different microalgae. Evaluating this, we used a different strain of Chlorella vulgaris and first characterized its surface properties using AFM. Results showed that cells were hydrophilic but could still interact with PO-chitosan on bubble surfaces through a different mechanism based on specific interactions. Although force levels were low, flotation resulted in 84% separation, which could be explained by the presence of AOM (algal organic matter) that also interacts with functionalized bubbles, enhancing the overall separation. Finally, flocculation was also shown to be efficient and pH-independent, demonstrating the potential of PO-chitosan for harvesting microalgae with different cell surface properties and thus for further sustainable large-scale applications.

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Section: Methodsmentioning

confidence: 99%

The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

Demir-Yilmaz,

Pappa,

Lama

et al. 2024

ACS Appl. Bio Mater.

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“…In many cases, the use of a combination of two or more harvesting methods can lead to further improvements in harvesting efficiency, production cost, and processing time [ 74 ]. A typical combination of harvesting techniques includes a pre-concentration/concentration step, followed by dewatering.…”

Section: Microalgae Harvesting: Exploring Suitable Strategy For Bulk ...mentioning

confidence: 99%

Biotechnologies for bulk production of microalgal biomass: from mass cultivation to dried biomass acquisition

Qin,

Wang,

Gao

et al. 2023

Biotechnol Biofuels

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Microalgal biomass represents a sustainable bioresource for various applications, such as food, nutraceuticals, pharmaceuticals, feed, and other bio-based products. For decades, its mass production has attracted widespread attention and interest. The process of microalgal biomass production involves several techniques, mainly cultivation, harvesting, drying, and pollution control. These techniques are often designed and optimized to meet optimal growth conditions for microalgae and to produce high-quality biomass at acceptable cost. Importantly, mass production techniques are important for producing a commercial product in sufficient amounts. However, it should not be overlooked that microalgal biotechnology still faces challenges, in particular the high cost of production, the lack of knowledge about biological contaminants and the challenge of loss of active ingredients during biomass production. These issues involve the research and development of low-cost, standardized, industrial-scale production equipment and the optimization of production processes, as well as the urgent need to increase the research on biological contaminants and microalgal active ingredients. This review systematically examines the global development of microalgal biotechnology for biomass production, with emphasis on the techniques of cultivation, harvesting, drying and control of biological contaminants, and discusses the challenges and strategies to further improve quality and reduce costs. Moreover, the current status of biomass production of some biotechnologically important species has been summarized, and the importance of improving microalgae-related standards for their commercial applications is noted.

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“…Air flotation is a wildly employed as cost-effective separation technology for several applications such as wastewater treatment, fermentation, plastic recycling, etc. (Ogunbiyi and Liu, 2023;Rao et al, 2023;Chen et al, 2023). The flotation process is basically relied on air bubbles are employed to capture the particles that their surfaces have varying degree of hydrophobicity and hydrophilicity.…”

Section: Introductionmentioning

confidence: 99%

Explore the Impact of Surfactant Type on the Stability and Separation Efficiency of Oil–Water Emulsions of Real Wastewater from Al-Basrah Crude Oil Using Microbubble Air Flotation

Al-yaqoobi,

Al-dulaimi,

Salman

2024

J. Ecol. Eng.

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Among several separation processes, the air flotation distinguish as remarkably high potential separation process related to its high separation efficiency and throughput, energy-efficient, simple process, cost-effective, applicable to a wide range of oily wastewater and no by-products. The current study aimed to investigate the effect of the type and concentration of surfactant on the stability of oil-water emulsion and efficiency of the separation process. For this purpose, three types of surfactant where used (anionic SDS, mixed nonionic Span 85/Tween 80, and cationic CTAB). The results demonstrated that the Span 85/Tween 80 surfactant has the best stability, and it increases with the surfactant concentration augmentation. The removal efficiency with CTAB surfactant reached to approximately 95% at concentration of 0.3%, and decreased by increasing the surfactant concentration. The mean diameter of bubbles generated in emulsion with CTAB surfactant was 71 µm, which was lower than that obtained with the other two surfactants.

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Microalgae harvesting using flocculation and dissolved air flotation: Selecting the right vessel for lab-scale experiments

Cited by 15 publications

References 43 publications

The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

Biotechnologies for bulk production of microalgal biomass: from mass cultivation to dried biomass acquisition

Explore the Impact of Surfactant Type on the Stability and Separation Efficiency of Oil–Water Emulsions of Real Wastewater from Al-Basrah Crude Oil Using Microbubble Air Flotation

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