Recyclable polyampholyte flocculants for the cost-effective dewatering of microalgae and cyanobacteria

Morrissey, Kathryn Lee; Keirn, Max I.; Inaba, Yuta; Denham, Annika J.; Henry, Graham J.; Vogler, Brian W.; Posewitz, Matthew C.; Stoykovich, Mark P.

doi:10.1016/j.algal.2015.07.009

Cited by 12 publications

(8 citation statements)

References 40 publications

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“…Although some applications may require remediation of the flocculants themselves from the solids stream with a downstream purification process, fortunately polyamphoteric flocculants with pH-dependent charge character provide opportunities for novel process implementation. We have shown recently that the flocculant -biocolloid interactions may be inverted (i.e., become repulsive interactions) by adjustment of the system pH following the solids recovery, such that the flocculant can be desorbed, recovered, and recycled for future usage [49,52]. Not only would such functional materials reduce the cost burden for flocculation, but may also enhance downstream processes (e.g., in microalgal harvesting by improving oil recovery from the concentrated biomass and reducing equipment fouling).…”

Section: Primary Dewatering By Flocculation Reduces the Burden On A Smentioning

confidence: 99%

“…For suspensions in the pH range of 8 to 12, it is therefore concluded that polyamphoteric flocculants provide a flocculating advantage over the cationic polyelectrolytes, which results from the presence of negative charges on the flocculant that interact with positive charges on the surface of the microalgal cells. This pH range is an important one for many biocolliodal and cellular suspensions as, for example, typical microalgal cultures are often basic (pHs of 8~10)and adopt a natural pH that is dependent upon many parameters including the stage of growth.Moreover, we have shown previously that the cationic polyelectrolytic and polyampholytic flocculants were able to remove >98% of microalgae from standard cultures when added in concentrations of 70-150 and 40-80 ppm, respectively, and allowing for a sedimentation time of 10 min[49,52]. The lower dosages required by the polyampholytic tPA flocculant cannot be explained by differences in flocculant molecular weight or molecular structure(Table 1), and rather are suggested to arise from the inclusion of the negative acrylic acid group that leads to electrostatic attraction with the positively-charged functionalities that are distributed on the cell surface.…”

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confidence: 99%

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Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Morrissey

Chapman

et al. 2016

Acta Biomaterialia

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This article presents the design and characterization of polyamphoteric flocculants for the separations of biocolloidal suspensions of importance in the production of biopharmaceuticals, microalgal cultures for nutraceuticals and biofuels, and wastewater treatment. The polyamphoteric flocculants consist of tunable, mixed charges dependent upon system pH, thereby providing strong electrostatic attraction to the diversely-charged surfaces of cellular suspensions. Enhanced flocculation efficiencies are achieved, as compared to cationic polyelectrolyte flocculants, and result from the ability of polyampholytes to adsorb to a diverse range of charge character and operate over an extended range of pH conditions.

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Section: Primary Dewatering By Flocculation Reduces the Burden On A Smentioning

confidence: 99%

mentioning

confidence: 99%

Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Morrissey

Chapman

et al. 2016

Acta Biomaterialia

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“…The common approach to dewatering microalgae is through a two-step process from dilute suspensions: (i) concentration of dilute suspensions to a slurry; and (ii) further dewatering the slurry to obtain a 'cake' . These steps are referred to as primary and secondary dewatering respectively [8,9]. The primary step aims at concentrating a suspension to a slurry of 2-7% biomass concentration, while the secondary further dewatering step could attain 15-30%, from which any further concentration will require an additional drying step [9].…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, low biomass recovery efficiency, high capital costs and/or high operating costs have become common attributes of currently deployed dewatering techniques. For a myriad of reasons, it is difficult to apply conventional dewatering techniques for microalgae biomass [8].…”

Section: Introductionmentioning

confidence: 99%

Single-step dynamic dewatering of microalgae from dilute suspensions using flocculant assisted filtration

et al. 2020

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Background Dewatering constitutes a major challenge to the production of microalgae, accounting for 20–30% of the product cost. This presents a setback for the applicability of microalgae in the development of several sustainable products. This study presents an investigation into the dynamic dewatering of microalgae in a combined flocculation-filtration process. The effect of process conditions on the performance of 12 flocculants and their mixtures was assessed. Results The mechanism of flocculation via the electrostatic path was dominated by charge neutralization and subsequently followed bridging in a ‘sweep flocculation’ process. Cationic polyacrylamide (CPAM) based flocculants recorded the highest biomass retention with PAM1 and PAM2 attaining 99 and 98% retention with flocculant dosages of 10 and 15 mg/L respectively. Polyvinylamine (PVAM) was also found to improve system stability across the pH range 4–10. Alum was observed to be only effective in charge neutralization, bringing the system close to its isoelectric point (IEP). Chemometric analysis using the multi-criteria decision methods, PROMETHEE and GAIA, was applied to provide a sequential performance ranking based on the net outranking flow (ф) from 207 observations. A graphical exploration of the flocculant performance pattern, grouping the observations into clusters in relation to the decision axis ($$\pi$$ π ), which indicated the weighted resultant of most favorable performance for all criteria was explored. Conclusion CPAM based flocculants and their mixtures demonstrated superior performance due to their viscoelastic behaviour under turbulence. The use of PVAM or alum in mixtures with CPAM reduced the required doses of both flocculants, which will provide beneficial financial impact for largescale microalgae dewatering in a flocculant assisted dynamic filtration process. Chemometric analysis based on the physico-chemical properties of the system provides a time saving assessment of performance across several criteria. The study findings provide an important foundation for flocculant assisted dynamic filtration processes.

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“…To allow for the recovery and reuse of flocculants or coagulants, detachment of the flocculants or coagulants from the microalgae must be achieved, for example by inducing changes in their surface properties, such as surface charge and wetting properties. ,− Such changes may be triggered by the presence of switchable or stimuli-responsive groups on the surface of the flocculants or coagulants. We recently reported a new CNC that is a CO 2 -switchable nanomaterial prepared by surface modification with 1-(3-aminopropyl)imidazole (APIm) .…”

Section: Introductionmentioning

confidence: 99%

Microalgae Recovery from Water for Biofuel Production Using CO₂-Switchable Crystalline Nanocellulose

Champagne

Wang

et al. 2016

Environ. Sci. Technol.

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There is a pressing need to develop efficient and sustainable approaches to harvesting microalgae for biofuel production and water treatment. CO2-switchable crystalline nanocellulose (CNC) modified with 1-(3-aminopropyl)imidazole (APIm) is proposed as a reversible coagulant for harvesting microalgae. Compared to native CNC, the positively charged APIm-modified CNC, which dispersed well in carbonated water, showed appreciable electrostatic interaction with negatively charged Chlorella vulgaris upon CO2-treatment. The gelation between the modified CNC, triggered by subsequent air sparging, can also enmesh adjacent microalgae and/or microalgae-modified CNC aggregates, thereby further enhancing harvesting efficiencies. Moreover, the surface charges and dispersion/gelation of APIm-modified CNC could be reversibly adjusted by alternatively sparging CO2/air. This CO2-switchability would make the reusability of redispersed CNC for further harvesting possible. After harvesting, the supernatant following sedimentation can be reused for microalgal cultivation without detrimental effects on cell growth. The use of this approach for harvesting microalgae presents an advantage to other current methods available because all materials involved, including the cellulose, CO2, and air, are natural and biocompatible without adverse effects on the downstream processing for biofuel production.

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Recyclable polyampholyte flocculants for the cost-effective dewatering of microalgae and cyanobacteria

Cited by 12 publications

References 40 publications

Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Single-step dynamic dewatering of microalgae from dilute suspensions using flocculant assisted filtration

Microalgae Recovery from Water for Biofuel Production Using CO₂-Switchable Crystalline Nanocellulose

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Recyclable polyampholyte flocculants for the cost-effective dewatering of microalgae and cyanobacteria

Cited by 12 publications

References 40 publications

Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Polyamphoteric flocculants for the enhanced separation of cellular suspensions

Single-step dynamic dewatering of microalgae from dilute suspensions using flocculant assisted filtration

Microalgae Recovery from Water for Biofuel Production Using CO2-Switchable Crystalline Nanocellulose

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Product

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Microalgae Recovery from Water for Biofuel Production Using CO₂-Switchable Crystalline Nanocellulose