Guluronic acid content as a factor affecting turbidity removal potential of alginate

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Moral C. K., Ertesvag H., Sanin F. D.

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, vol.23, pp.22568-22576, 2016 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 23
  • Publication Date: 2016
  • Doi Number: 10.1007/s11356-016-7475-6
  • Journal Name: ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.22568-22576
  • Keywords: Alginate, Azotobacter vinelandii, Coagulation, Guluronic acid blocks, Turbidity removal, GRAFTED SODIUM ALGINATE, AZOTOBACTER-VINELANDII, MONOMER DISTRIBUTION, FLOCCULATION, OXYGEN, POLYSACCHARIDES, COAGULATION, METABOLISM, BIOPOLYMER
  • Middle East Technical University Affiliated: Yes

Abstract

Alginates are natural polymers composed of mannuronic and guluronic acid residues. They are currently extracted from brown algae; however, alginate can also be synthesized by some species of Azotobacter and Pseudomonas. Alginates with different proportion of mannuronic and guluronic acids are known to have different characteristics and form gels at different extents in the presence of calcium ions. The aim of this work was to investigate the usefulness of alginate as a non-toxic coagulant used in purification of drinking water. This study utilized alginates from Azotobacter vinelandii having different guluronic acid levels. These were obtained partly by changing the cultivation parameters, partly by epimerizing a purified alginate sample in vitro using the A. vinelandii mannuronan C-5 epimerase AlgE1. The different alginates were then used for coagulation together with calcium. The results showed that turbidity removal capability was dependent on the content of guluronic acid residues. For the best performing samples, the turbidity decreased from 10 NTU to 1 NTU by the use of only 2 mg/L of alginate and 1.5 mM of calcium chloride.