Terminal settling velocity and bed-expansion characteristics of biofilm- coated particles

Cristiano Nicolella, Mark M.C. Van Loosdrecht, Renzo Di Felice, Mauro Rovatti

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Fluid dynamic behavior of biofilm-coated particles in ambient water has been investigated. New experimental results are presented and compared with published data. From experimental measurements of the single particle terminal settling velocity the corresponding drag coefficient was found to be larger (by a factor of 1.6) than that for a smooth, rigid sphere at the same Reynolds number. A new simple correlation describing this finding is suggested. For multiparticle systems the Richardson-Zaki equation, derived empirically for rigid particles, provided a satisfactory description of biological beds. Of the two numerical parameters characterizing the expansion law, i.e. the slope n and the extrapolation to voidage equal one u(i), the first was found to be similar to that suggested by Richardson and Zaki (1954), whereas u(i) gave results smaller than the single-particle terminal settling velocity, in contrast with the mentioned work but in agreement with more recently published behavior.

Original languageEnglish
Pages (from-to)62-70
Number of pages9
JournalBiotechnology and Bioengineering
Issue number1
Publication statusPublished - Jan 5 1999


  • Biofilm reactors
  • Drag coefficient, bed expansion
  • Liquid fluidized beds

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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