Effect of organic loading rate on a wastewater treatment process combining moving bed biofilm and membrane reactors

E. Melin*, T. Leiknes, H. Helness, V. Rasmussen, H. Ødegaard

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


The effect of moving bed biofilm reactor (MBBR) loading rate on membrane fouling rate was studied in two parallel units combining MBBR and membrane reactor. Hollow fiber membranes with molecular weight cut-off of 30 kD were used. The HRTs of the MBBRs varied from 45 min to 4h and the COD loading rates ranged from 4.1 to 26.6 g COD m-2 d-1. The trans-membrane pressure (TMP) was very sensitive to fluxes for the used membranes and the experiments were carried out at relatively low fluxes (3.3-5.61 m-2 h-1). Beside the test with the highest flux, there were no consistent differences in fouling rate between the low- and high-rate reactors. Also, the removal efficiencies were quite similar in both systems. The average COD removal efficiencies in the total process were 87% at 3-4 h HRT and 83% at 0.75-1 h HRT. At high loading rates, there was a shift in particle size distribution towards smaller particles in the MBBR effluents. However, 79-81% of the COD was in particles that were separated by membranes, explaining the relatively small differences in the removal efficiencies at different loading rates. The COD fractionation also indicated that the choice of membrane pore size within the range of 30 kD to 0.1 μm has very small effect on the COD removal in the MBBR/membrane process, especially with low-rate MBBRs.

Original languageEnglish (US)
Pages (from-to)421-430
Number of pages10
JournalWater Science and Technology
Issue number6-7
StatePublished - 2005
Externally publishedYes


  • Membrane reactor
  • Moving bed biofilm reactor
  • Particle size distribution
  • Wasterwater treatment

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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