Controlling cyanobacterial blooms through effective flocculation and sedimentation with combined use of flocculants and phosphorus adsorbing natural soil and modified clay

Natalia Pessoa Noyma*, L. de Magalhaes, L.L. Furtado, M. Nunes Teixeira Mucci, M. van Oosterhout, V.L.M. Huszar, M.M. Marinho, M.F.L.L.W. Lurling

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

101 Citations (Scopus)

Abstract

Eutrophication often results in blooms of toxic cyanobacteria that hamper the use of lakes and reservoirs. In this paper, we experimentally evaluated the efficacy of a metal salt (poly-aluminium chloride, PAC) and chitosan, alone and combined with different doses of the lanthanum modified bentonite Phoslock® (LMB) or local red soil (LRS) to sediment positively buoyant cyanobacteria from Funil Reservoir, Brazil, (22°30’S, 44°45’W). We also tested the effect of calcium peroxide (CaO2) on suspended and settled cyanobacterial photosystem efficiency, and evaluated the soluble reactive P (SRP) adsorbing capacity of both LMB and LRS under oxic and anoxic conditions. Our data showed that buoyant cyanobacteria could be flocked and effectively precipitated using a combination of PAC or chitosan with LMB or LRS. The SRP sorption capacity of LMB was higher than that of LRS. The maximum P adsorption was lowered under anoxic conditions especially for LRS ballast. CaO2 addition impaired photosystem efficiency at 1 mg L-1 or higher and killed precipitated cyanobacteria at 4 mg L-1 or higher. A drawback was that oxygen production from the peroxide gave positive buoyancy again to the settled flocs. Therefore, further experimentations with slow release pellets are recommended.
Original languageEnglish
Pages (from-to)26-38
JournalWater Research
Volume97
DOIs
Publication statusPublished - 2016

Keywords

  • Cyanobacteria bloom
  • Geo-engineering in lakes
  • Lake restoration
  • Local red soil
  • Phosphorus mitigation

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