A novel concept for evaluation of biofilm adhesion strength by applying tensile force and shear force

A. Ohashi, H. Harada

Research output: Contribution to journalConference articlepeer-review

52 Citations (Scopus)


A novel methodology is proposed in this study to evaluate biofilm adhesion strength in two different ways: by measuring detached biomass caused by tensile force and by shear force. Tensile force was provided by centrifuging biofilm-attached plates installed on rotary tables. Shear force was provided by colliding biofilm-attached plates by gravity. Test biofilms consisting of denitrifiers were formed on the flat surfaces of square (25 cm2) plates that had been submerged in a rectangular open-channel reactor. The detachment tests revealed that, although biofilm adhesion strength was relatively high at the earlier growth stage, it drastically decreased at the later stage. The most weakened location toward biofilm depth was observed at the substratum surface, at which the adhesion strength by tensile force dropped from a several Pa to below 1 Pa as biofilms became aged. The adhesion strength by shear force was all the time more than 100 times as large as that by tensile force, even though having a similar behavior. The proportion of cavity, i.e., biofilm-absent area at the biofilm/substratum interface, increased as biofilms became mature. Cavity formation was strongly responsible for lessening the adhesion strength. It is suggested that biofilm slough-off is caused by the decline of adhesion strength by tensile force rather than by shear force.

Original languageEnglish
Pages (from-to)201-211
Number of pages11
JournalWater Science and Technology
Issue number5-6 -6 pt 3
Publication statusPublished - 1996
Externally publishedYes
EventProceedings of the 1996 18th Biennial Conference of the International Association on Water Quality. Part 3 - Singapore, Singapore
Duration: 1996 Jun 231996 Jun 28


  • Adhesion strength
  • Attached biofilm reactor
  • Cavity formation
  • Denitrifying biofilm
  • Extracellular biopolymer
  • Shear force
  • Sloughing
  • Tensile force

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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