Modeling the effect of biofilm formation on reverse osmosis performance: Flux, feed channel pressure drop and solute passage

A. I. Radu*, Johannes Vrouwenvelder, M. C.M. van Loosdrecht, C. Picioreanu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

84 Scopus citations

Abstract

A two-dimensional (2-d) mathematical model describing the effect of biofilm development on the performance of a spiral-wound reverse osmosis (RO) membrane device was developed. The micro-scale model combines hydrodynamics and mass transport of solutes (salt and substrate) with biomass attachment, biofilm growth and detachment due to mechanical stress induced by liquid flow in the feed channel. The model explains several experimental observations when operating at constant pressure: loss of permeate flux with increased salt passage in time and achievement of a quasi-steady state flux and biomass amount. The model also shows how the local balance between biofilm growth and detachment leads to irregular biofilm distribution in the feed channel and suggests places where most biomass accumulation is expected. Numerical simulations were performed in configurations without spacer or with different spacer geometries (submerged, cavity and zigzag). Three mechanisms were identified by which biofilms on RO membranes contribute to performance loss: (i) biofilm-enhanced concentration polarization; (ii) increased hydraulic resistance to trans-membrane flow; and (iii) increased feed channel pressure drop. For seawater and brackish water desalination, biofilm-enhanced concentration polarization appears to affect most the local flux. This modeling approach, combining computational fluid dynamics (CFD) with biofilm models allows a systematic study of biofouling in membrane systems. Moreover the approach is useful for improving feed spacer design and to evaluate operational conditions for minimum biofouling of reverse osmosis and nanofiltration (NF) membrane devices.

Original languageEnglish (US)
Pages (from-to)1-15
Number of pages15
JournalJournal of Membrane Science
Volume365
Issue number1-2
DOIs
StatePublished - Dec 1 2010

Keywords

  • Biofilm
  • Biofouling
  • Concentration polarization
  • Mathematical model
  • Membrane performance
  • Reverse osmosis

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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