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

Area of Science:

• Environmental science
• Virology
• Public health

Background:

• Municipal sewage contains SARS-CoV-2 RNA from COVID-19 patients.
• Effective wastewater treatment is vital to prevent environmental virus dissemination.
• The impact of different treatment stages on viral RNA reduction remains unclear.

Purpose of the Study:

• To quantify SARS-CoV-2 RNA concentrations in raw sewage and during activated sludge treatment stages.
• To evaluate the effectiveness of wastewater treatment processes in reducing viral RNA.
• To assess the role of tertiary treatment and chlorination in virus inactivation.

Main Methods:

• Samples collected from two Israeli wastewater treatment plants during the 2020 COVID-19 outbreak.
• Ultrafiltration used for sample concentration (2-43 fold) to lower detection limits.
• Quantification of SARS-CoV-2 RNA via real-time polymerase chain reaction.

Main Results:

• Primary and secondary treatment steps achieved approximately 1-log RNA removal on average.
• >100 copies of SARS-CoV-2 RNA/mL were detected in secondary effluents.
• SARS-CoV-2 RNA was rarely detected after chlorination, suggesting treatment efficacy, potentially limited by chlorine dosage.

Conclusions:

• Conventional wastewater treatment partially reduces SARS-CoV-2 RNA.
• Tertiary treatment and chlorination are important for minimizing environmental virus release.
• Further research is needed to optimize treatment for complete viral inactivation.