A fungal immobilization technique for efficient harvesting of oleaginous microalgae: Key parameter optimization, mechanism exploration and spent medium recycling

Chu, Ruoyu; Li, Shuangxi; Yin, Zhaoyi; Hu, Dan; Zhang, Lingbo; Xiang, Ming; Zhu, Linna

doi:10.1016/j.scitotenv.2021.148174

Cited by 35 publications

(7 citation statements)

References 45 publications

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“…The extracellular component of Aspergillus niger functions as an adhesive that has a positive charge in the presence of a polysaccharide hydroxyl group (glucan, glycoprotein, chitin, and melanin) [10]; [21]. The hydroxyl cations from the fungus will absorb the negative charge from around the microalgae surface so that it has a bridging effect [11]. The positive charge of the fungal pellet will attract negative microalgae ions by coagulation so that the charge undergoes a neutralization process [14]; [11].…”

Section: Effect Of Bioflocculation On Bioflocculant Dosagementioning

confidence: 99%

“…The hydroxyl cations from the fungus will absorb the negative charge from around the microalgae surface so that it has a bridging effect [11]. The positive charge of the fungal pellet will attract negative microalgae ions by coagulation so that the charge undergoes a neutralization process [14]; [11]. The neutralization process will eliminate the electrostatic repulsion between the particles, then they will agglomerate to form flocs [14].…”

Section: Effect Of Bioflocculation On Bioflocculant Dosagementioning

confidence: 99%

“…Bioflocculation occurred neutralization of cationic hydroxyl from fungal pellets distributed to the anionic surface of microalgae [11]; [10]. However, the process of neutralization by uneven ions requires a charge patch on the surface of the microalgae.…”

Section: Effect Of Bioflocculation On the Cationic Inducers Concentra...mentioning

confidence: 99%

“…The floc will settle due to gravity [10]. EPS fungi have long chains and large molecular weights, so they can increase the sedimentation rate and density of microalgae [6]; [11]. Aspergillus niger is a filamentous fungus capable of forming pellets due to granulation [12].…”

Section: Introductionmentioning

confidence: 99%

“…Aspergillus niger is a filamentous fungus capable of forming pellets due to granulation [12]. Pellet formation occurs through mycelium interaction by fungal hyphae branches [11]. The method of bioflocculation of Chlorella vulgaris with the help of Aspergillus niger pellets has the following advantages: the process is simple, low cost, non-toxic, environmentally friendly, easy to separate, and increases the mass transfer rate [13]; [14]; [11].…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Bioflocculants and Cationic Inducers Concentration on Harvesting Chlorella vulgaris Biomass Using Fungal Aspergillus niger Bioflocculation Method

Isaroyati

Hadiyanto

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Energy consumption from non-renewable fuels is increasing, so there is a need for a new energy source from microalgae. The microalgae Chlorella vulgaris has a high lipid content ranging from 2-77% of the dry weight of the biomass, but it small size, ranging from 2-10 micrometers, which makes it uneconomical at the harvesting stage. One of the cheaper, effective, and environmentally-friendly harvesting methods is bioflocculation. The bioflocculation was carried out using the help of fungi by activating Extracellular Polymeric Substances (EPS) on positively charged fungi which would stick to negatively charged microalgae so that the charge became neutral and formed flocs. Previous research on the efficiency of harvesting bioflocculation of Chlorella vulgaris using Aspergillus niger pellets still takes a long time. Harvesting of Chlorella vulgaris with Aspergillus niger pellets was able to increase the efficiency of bioflocculation with the optimal parameters which were at pH 8, cationic inducer of 60 mM, bioflocculant dose of 3.5% w/v, and stirring speed of 150 rpm by 93% with a biomass of 333 mg within 48 hours. The bioflocculation harvesting method with fungi pellets can reduce time, save energy, increase harvesting efficiency, and not produce side products so harmful to the environment.

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Section: Effect Of Bioflocculation On Bioflocculant Dosagementioning

confidence: 99%

Section: Effect Of Bioflocculation On Bioflocculant Dosagementioning

confidence: 99%

Section: Effect Of Bioflocculation On the Cationic Inducers Concentra...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Effect of Bioflocculants and Cationic Inducers Concentration on Harvesting Chlorella vulgaris Biomass Using Fungal Aspergillus niger Bioflocculation Method

Isaroyati

Hadiyanto

2022

IOP Conf. Ser.: Earth Environ. Sci.

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Bioflocculation of Euglena gracilis via direct application of fungal filaments: a rapid harvesting method

et al. 2021

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The high cost and environmental impact of traditional microalgal harvesting methods limit commercialization of microalgal biomass. Fungal bioflocculation of microalgae is a promising low-cost, eco-friendly method but the range of fungal and microalgal species tested to date is narrow. Here, eight non-pathogenic, filamentous fungi were screened for their ability to self-pelletize and flocculate Euglena gracilis (ca.50 µm motile microalga) in suspension. Self-pelletization was tested under various rotational speeds, and species which formed pellets (Ø > 0.5 cm) were selected for harvesting tests. Filaments of each species were combined with E. gracilis at various ratios based on dry weight. Harvesting efficiency was determined by measuring the change in cell counts over time, and settling of the flocs was evaluated by batch settling tests. Three fungal species, Ganoderma lucidum, Pleurotus ostreatus, and Penicillium restrictum, were able to reliably flocculate and harvest 62–75% of the microalgae while leaving it unharmed. The results demonstrated that self-pelletization, harvesting, and settling were dependent on the fungal species. The fungi to algae ratio also had significant but contrasting effects on harvesting and settling. In balancing the needs to both harvest and settle the biomass, the optimal fungi to algae ratio was 1:2. The application of fungal filaments to microalgae in suspension produced readily settling flocs and was less time-consuming than other commonly used methods. This method is especially attractive for harvesting microalgal biomass for low-value products where speed, low cost, and cell integrity is vital.

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Bioflocculation harvesting of oleaginous microalga Chlorella sp. using novel lipid-rich cellulolytic fungus Aspergillus terreus (MD1) for biodiesel production

Ayad,

Matter,

Gharieb

et al. 2023

Biomass Conv. Bioref.

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The isolation of lipid-rich cellulolytic fungi was targeted to be investigated as bioflocculant agents for microalgae harvesting. The fungal isolate coded MD1 was selected based on its lipid content, cellulolytic activity, and its harvesting efficiency for the freshwater oleaginous microalga Chlorella sp. The selected fungus which was molecularly identified as Aspergillus terreus has been applied as bioflocculant after solid state cultivation on pre-treated rice straw (as abundant agro-cellulosic waste). Optimization of harvesting efficiency of Chlorella microalga using A. terreus/rice straw biomass as the “bioflocculant” was investigated. The optimization conditions included microalga/bioflocculant ratio, microalgal age, contact time between the bioflocculant and the microalga, pH of microalgal culture at harvesting time, and cell density of microalgal culture. The obtained results revealed that the harvesting efficiency could reach 97.6% due to 24 h as contact time at 30% flocculant/microalga ratio and pH 7. While after 2 h contact time, 93.3% harvesting efficiency could be obtained using the same bioflocculant:microalga ratio at pH 6. The lipid extracted from harvested Chlorella/A. terreus mixture was applied to produce biodiesel (fatty acid methyl ester) after methylation. The resulted biodiesel contains high percentage (67.2%) of C18:1,2 unsaturated fatty acids which is considered a suitable fraction for biodiesel production. Obtained results revealed the suitability of the novel A. terreus strain as sustainable bioflocculation agent to harvest microalga(e) for biofuel production.

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A fungal immobilization technique for efficient harvesting of oleaginous microalgae: Key parameter optimization, mechanism exploration and spent medium recycling

Cited by 35 publications

References 45 publications

The Effect of Bioflocculants and Cationic Inducers Concentration on Harvesting Chlorella vulgaris Biomass Using Fungal Aspergillus niger Bioflocculation Method

The Effect of Bioflocculants and Cationic Inducers Concentration on Harvesting Chlorella vulgaris Biomass Using Fungal Aspergillus niger Bioflocculation Method

Bioflocculation of Euglena gracilis via direct application of fungal filaments: a rapid harvesting method

Bioflocculation harvesting of oleaginous microalga Chlorella sp. using novel lipid-rich cellulolytic fungus Aspergillus terreus (MD1) for biodiesel production

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