Tracking SARS-CoV‑2 RNA through the Wastewater Treatment Process

Hala Abu Ali, Karin Yaniv, Edo Bar-Zeev, Sanhita Chaudhury, Marilou Shagan, Satish Lakkakula, Zeev Ronen, Ariel Kushmaro, Oded Nir

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Municipal sewage carries degraded and intact viral particles and RNA (ribonucleic acid) of SARS-CoV-2 (severe acute respiratory coronavirus 2), shed by COVID-19 (coronavirus disease 2019) patients, to sewage and eventually to wastewater treatment plants. Proper wastewater treatment can prevent uncontrolled discharges of the virus into the environment. However, the role of different wastewater treatment stages in reducing viral RNA concentrations is, thus far, unknown. Here, we quantified SARS-CoV-2 RNA in raw sewage and during the main stages of the activated sludge process from two wastewater treatment plants in Israel, on three different days during the 2020 COVID-19 outbreak. To reduce the detection limit, samples were concentrated prior to quantification by real-time polymerase chain reaction by a factor of 2−43 using ultrafiltration. On average, ∼1 log RNA removal was attained by each of the primary and secondary treatment steps; however, >100 copies of SARS-CoV-2 RNA/ mL remained in the secondary effluents. Following chlorination, SARS-CoV-2 RNA was detected only once, likely due to an insufficient chlorine dose. Our results emphasize the capabilities and limitations of the conventional wastewater treatment process in reducing the SARS-CoV-2 RNA concentration and present preliminary evidence for the importance of tertiary treatment and chlorination in reducing dissemination of the virus to the environment.

Original languageEnglish
Pages (from-to)1161-1167
Number of pages7
JournalACS ES and T Water
Issue number5
StatePublished - 14 May 2021


  • coronavirus
  • COVID-19
  • fecal−oral transmission
  • occupational health
  • SARS-CoV-2 in sewage
  • viral RNA
  • virus preconcentration
  • virus removal

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Chemistry (miscellaneous)
  • Environmental Chemistry
  • Water Science and Technology


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