Low concentrations of Al(III) accelerate the formation of biofilm: Multiple effects of hormesis and flocculation

Xiaochun Cui, Mingxin Huo, Congli Chen, Zhisen Yu, Chen Zhou, Anran Li, Bingqian Qiao, Dandan Zhou, John C. Crittenden

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Residual Al(III) (at low concentration) is common in water treatment plants (WTPs) and is associated with bacteria. We hypothesize that Al(III) accelerate biofouling due to its hydrolysis and hormesis characteristics, as compared with other cations. To verify this, we elaborated the roles of Al(III) at low concentrations on the biofilm formation. Al(III) hormesis (<2.0 mg/L) stimulated bacteria growth increased by ~3.7 times, and extracellular polymeric substances production also enhanced. Al(III) flocculation resulted in the suspended cells precipitation instantly, for Al(III) dosages of 0.6 and 2.0 mg/L and the concentration of Al(III) decreased by 0.07 and 0.14 mg/L, respectively. Al(III) poisoned the bridged bacterial cells and decreased their ATP by 22.36% and 55.91%, respectively. Al(III) formed polymer presented strong affinity with bacterial outer membrane, and this damaged the bacterial outer membrane. This caused proteins to leak at the combined point. Al-polymer bound to –NH2 and/or –NH– on the leaked protein, contributed to biofilm formation. Biofilm maturity was aided by polysaccharides, which shielded Al(III) toxicity for the formed biofilm. Thus, the biofilm exhibited a distinguished double-layer microstructure, principally with proteins and inactivated cells at the bottom, polysaccharides and activated cells at the top. Thus, hormesis and flocculation caused by low concentration Al(III) mutually promoted each other, and together accelerated biofilm formation.

Original languageEnglish (US)
Pages (from-to)516-524
Number of pages9
JournalScience of the Total Environment
Volume634
DOIs
StatePublished - Sep 1 2018
Externally publishedYes

Keywords

  • Aluminum
  • Biofilm
  • Coagulant
  • Flocculation
  • Hormesis
  • Toxicity

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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