Disinfection of greywater effluent and regrowth potential of selected bacteria

Eran Friedler, Anat Yardeni, Yael Gilboa, Yuval Alfiya

Research output: Contribution to journalArticlepeer-review


Chlorination and UV irradiation of RBC (rotating biological contactor)-treated light GW (greywater) was investigated. The ability of chlorine and UV to inactivate indictor bacteria (FC - Faecal Coliforms, HPC - Heterotrophic Plate Count) and specific pathogens (P.a. - Pseudomonas aeruginosa sp., S.a. - Staphylococcus aureus sp.), was assessed and their regrowth potential was examined. The RBC removed 88.5-99.9% of all four bacteria groups. Nevertheless, the treated GW had to be disinfected. Most of the chlorine was consumed during the first 0.5 h, while later its decay rate decreased significantly, leaving enough residual after 6 h to prevent regrowth and to further inactivate bacteria in the stored GW effluent. Under exposure to low UV doses (≤69 mJ/cm2) FC was the most resistant bacteria group, followed by HPC, P.a. and S.a. Exposure to higher doses (≤439 mJs/cm 2) completely inactivated FC, P.a. and S.a., while no further HPC inactivation was observed. FC, P.a. and S.a. did not exhibit regrowth after exposure to all the UV doses applied (up to 6 h storage). HPC did not exhibit regrowth after exposure to low UV doses (19-69 mJ/cm2), while it presented statistically significant regrowth in un-disinfected effluent and after exposure to higher UV doses (147-439 mJ/cm2).

Original languageEnglish
Pages (from-to)931-940
Number of pages10
JournalWater Science and Technology
Issue number5
StatePublished - 2011


  • Chlorination
  • Disinfection
  • Greywater
  • Microbial quality
  • Regrowth potential
  • UV disinfection

All Science Journal Classification (ASJC) codes

  • Water Science and Technology
  • Environmental Engineering


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