Coagulation-flocculation of Microcystis aeruginosa by polymer-clay based composites

Ido Gardi; Yael Golda Mishael; Marika Lindahl; Alicia M. Muro-Pastor; Tomás Undabeytia

doi:10.1016/j.jclepro.2023.136356

Coagulation-flocculation of Microcystis aeruginosa by polymer-clay based composites

Ido Gardi, Yael Golda Mishael, Marika Lindahl, Alicia M. Muro-Pastor, Tomás Undabeytia^*

^*Corresponding author for this work

Department of Soil and Water Sciences

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Coagulation-flocculation is a critical treatment to reduce operational problems at Drinking Water Treatment Plants (DWTPs), created by episodes of cyanobacterial blooms in surface waters. There is a need for the search of good coaguflocculants that avoid release of intracellular toxins for a safer sustainable production. Clay-polymer interactions were examined for the development of efficient composites for their use as coaguflocculants for Microcystis aeruginosa (M. aeruginosa) suspensions. Polymers derived from poly-4-vinylpyridine (PVP) were quaternized on the pyridinic N by introducing methyl and hydroxyethyl moieties. These polymers were toxic per se; however, composites prepared either from their sorption or grafting on the clay surface of a montmorillonite exhibited null toxicity, The combination of infrared and X-ray diffraction data with thermal analysis showed a train conformation of the sorbed polymers on the clay surface whereas a brush conformation was elucidated for the grafted polymers. Only the composite prepared from grafting and subsequent quaternization with methyls was an efficient coaguflocculant, due to its high positive surface potential (+39 mV) which allowed a close contact between the quaternary moieties of the brushes and the negative cell wall. A patch flocculation mechanism was involved, with the riks of resuspension of the coagulated cells if the composite added in excess. The optimum ratio between the amount of coagulated cyanobacteria and this composite expressed as equivalent to polymer content was 7.2 × 10⁷ cells/mg polymer. This ratio was determined in axenic cultures of M. aeruginosa, but was reduced 5-fold in natural surface waters due to natural organic matter (NOM) content and heterogeneity. This study has demonstrated the relevance of the type of modification of the clay mineral surface with polymers to obtain good coaguflocculants of cyanobacterial cells, that can be extended to other microorganisms.

Original language	American English
Article number	136356
Journal	Journal of Cleaner Production
Volume	394
DOIs	https://doi.org/10.1016/j.jclepro.2023.136356
State	Published - 25 Mar 2023

Bibliographical note

Funding Information:
This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R ). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja.

Funding Information:
This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja.

Publisher Copyright:
© 2023 The Authors

Keywords

Coagulation-flocculation
Cyanobacteria
Polymer-clay composites
Surface waters

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.jclepro.2023.136356

Cite this

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title = "Coagulation-flocculation of Microcystis aeruginosa by polymer-clay based composites",

abstract = "Coagulation-flocculation is a critical treatment to reduce operational problems at Drinking Water Treatment Plants (DWTPs), created by episodes of cyanobacterial blooms in surface waters. There is a need for the search of good coaguflocculants that avoid release of intracellular toxins for a safer sustainable production. Clay-polymer interactions were examined for the development of efficient composites for their use as coaguflocculants for Microcystis aeruginosa (M. aeruginosa) suspensions. Polymers derived from poly-4-vinylpyridine (PVP) were quaternized on the pyridinic N by introducing methyl and hydroxyethyl moieties. These polymers were toxic per se; however, composites prepared either from their sorption or grafting on the clay surface of a montmorillonite exhibited null toxicity, The combination of infrared and X-ray diffraction data with thermal analysis showed a train conformation of the sorbed polymers on the clay surface whereas a brush conformation was elucidated for the grafted polymers. Only the composite prepared from grafting and subsequent quaternization with methyls was an efficient coaguflocculant, due to its high positive surface potential (+39 mV) which allowed a close contact between the quaternary moieties of the brushes and the negative cell wall. A patch flocculation mechanism was involved, with the riks of resuspension of the coagulated cells if the composite added in excess. The optimum ratio between the amount of coagulated cyanobacteria and this composite expressed as equivalent to polymer content was 7.2 × 107 cells/mg polymer. This ratio was determined in axenic cultures of M. aeruginosa, but was reduced 5-fold in natural surface waters due to natural organic matter (NOM) content and heterogeneity. This study has demonstrated the relevance of the type of modification of the clay mineral surface with polymers to obtain good coaguflocculants of cyanobacterial cells, that can be extended to other microorganisms.",

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note = "Funding Information: This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R ). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja. Funding Information: This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja. Publisher Copyright: {\textcopyright} 2023 The Authors",

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AU - Undabeytia, Tomás

N1 - Funding Information: This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R ). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja. Funding Information: This work has received financial support from the Spanish Ministry of Science and Innovation (project CTM2016-77168-R). The authors also acknowledge the Services of the University of Seville (CITIUS) of Biology for flow cytometer analysis, and of Microanalysis and Functional Characterisation for determination of zeta potentials, loading of the polymers and MC-LR analysis. They also acknowledge the Microscopy Service of the CIC Isla de la Cartuja. Publisher Copyright: © 2023 The Authors

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N2 - Coagulation-flocculation is a critical treatment to reduce operational problems at Drinking Water Treatment Plants (DWTPs), created by episodes of cyanobacterial blooms in surface waters. There is a need for the search of good coaguflocculants that avoid release of intracellular toxins for a safer sustainable production. Clay-polymer interactions were examined for the development of efficient composites for their use as coaguflocculants for Microcystis aeruginosa (M. aeruginosa) suspensions. Polymers derived from poly-4-vinylpyridine (PVP) were quaternized on the pyridinic N by introducing methyl and hydroxyethyl moieties. These polymers were toxic per se; however, composites prepared either from their sorption or grafting on the clay surface of a montmorillonite exhibited null toxicity, The combination of infrared and X-ray diffraction data with thermal analysis showed a train conformation of the sorbed polymers on the clay surface whereas a brush conformation was elucidated for the grafted polymers. Only the composite prepared from grafting and subsequent quaternization with methyls was an efficient coaguflocculant, due to its high positive surface potential (+39 mV) which allowed a close contact between the quaternary moieties of the brushes and the negative cell wall. A patch flocculation mechanism was involved, with the riks of resuspension of the coagulated cells if the composite added in excess. The optimum ratio between the amount of coagulated cyanobacteria and this composite expressed as equivalent to polymer content was 7.2 × 107 cells/mg polymer. This ratio was determined in axenic cultures of M. aeruginosa, but was reduced 5-fold in natural surface waters due to natural organic matter (NOM) content and heterogeneity. This study has demonstrated the relevance of the type of modification of the clay mineral surface with polymers to obtain good coaguflocculants of cyanobacterial cells, that can be extended to other microorganisms.

AB - Coagulation-flocculation is a critical treatment to reduce operational problems at Drinking Water Treatment Plants (DWTPs), created by episodes of cyanobacterial blooms in surface waters. There is a need for the search of good coaguflocculants that avoid release of intracellular toxins for a safer sustainable production. Clay-polymer interactions were examined for the development of efficient composites for their use as coaguflocculants for Microcystis aeruginosa (M. aeruginosa) suspensions. Polymers derived from poly-4-vinylpyridine (PVP) were quaternized on the pyridinic N by introducing methyl and hydroxyethyl moieties. These polymers were toxic per se; however, composites prepared either from their sorption or grafting on the clay surface of a montmorillonite exhibited null toxicity, The combination of infrared and X-ray diffraction data with thermal analysis showed a train conformation of the sorbed polymers on the clay surface whereas a brush conformation was elucidated for the grafted polymers. Only the composite prepared from grafting and subsequent quaternization with methyls was an efficient coaguflocculant, due to its high positive surface potential (+39 mV) which allowed a close contact between the quaternary moieties of the brushes and the negative cell wall. A patch flocculation mechanism was involved, with the riks of resuspension of the coagulated cells if the composite added in excess. The optimum ratio between the amount of coagulated cyanobacteria and this composite expressed as equivalent to polymer content was 7.2 × 107 cells/mg polymer. This ratio was determined in axenic cultures of M. aeruginosa, but was reduced 5-fold in natural surface waters due to natural organic matter (NOM) content and heterogeneity. This study has demonstrated the relevance of the type of modification of the clay mineral surface with polymers to obtain good coaguflocculants of cyanobacterial cells, that can be extended to other microorganisms.

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KW - Cyanobacteria

KW - Polymer-clay composites

KW - Surface waters

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Coagulation-flocculation of Microcystis aeruginosa by polymer-clay based composites

Abstract

Bibliographical note

Keywords

UN SDGs

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