The impact of interactions between algal organic matter and humic substances on coagulation

This study focuses on the effects of molecular interactions between two natural organic matter (NOM) fractions, peptides/proteins derived from cyanobacterium Microcystis aeruginosa (MA proteins) and peat humic substances (HS), on their removal by coagulation. Coagulation behaviour was studied by the...

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Bibliographic Details
Published in:Water research (Oxford) 2015-11, Vol.84, p.278-285
Main Authors: Pivokonsky, Martin, Naceradska, Jana, Brabenec, Tomas, Novotna, Katerina, Baresova, Magdalena, Janda, Vaclav
Format: Article
Language:English
Subjects:
Algae
Animals
Bovine serum albumin
Cattle
Charge
Charging
Coagulants
Coagulation
Cyanobacteria
Functional groups
Humic Substances
Microcystis aeruginosa
Natural organic matter
Peptides - metabolism
Peptides/proteins
Proteins
Proteins - metabolism
Water Purification - methods
Water treatment
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Summary:This study focuses on the effects of molecular interactions between two natural organic matter (NOM) fractions, peptides/proteins derived from cyanobacterium Microcystis aeruginosa (MA proteins) and peat humic substances (HS), on their removal by coagulation. Coagulation behaviour was studied by the jar tests with MA protein/HS mixtures and with single compounds (MA proteins or HS). Aluminium sulphate was used as a coagulant. Besides MA proteins, bovine serum albumin (BSA) was used as a model protein. For the MA protein/HS mixture, the removal rates were higher (80% versus 65%) and the dose of coagulant substantially lower (2.8 versus 5.5 mg L−1 Al) than for coagulation of single HS, indicating the positive effect of protein-HS interactions on the coagulation process. The optimum coagulation pH was 5.2–6.7 for MA proteins and 5.5–6 for HS by alum. The optimum pH for the removal of MA protein/HS mixture ranged between pH 5.5–6.2, where the charge neutralization of negatively charged acidic functional groups of organic molecules by positively charged coagulant hydroxopolymers lead to coagulation. MA proteins interacted with HS, probably through hydrophobic, dipole–dipole and electrostatic interactions, even in the absence the coagulant. These interactions are likely to occur within a wide pH range, but they result in coagulation only at low pH values (pH 
ISSN:0043-1354
1879-2448
DOI:10.1016/j.watres.2015.07.047