Impacts of virus processing on human norovirus GI and GII persistence during disinfection of municipal secondary wastewater effluent

Nathan Dunkin; ShihChi Weng; Caroline G Coulter; Joseph G Jacangelo; Kellogg J Schwab

doi:10.1016/j.watres.2018.01.053

Impacts of virus processing on human norovirus GI and GII persistence during disinfection of municipal secondary wastewater effluent

Water Res. 2018 May 1:134:1-12. doi: 10.1016/j.watres.2018.01.053. Epub 2018 Feb 20.

Authors

Nathan Dunkin¹, ShihChi Weng², Caroline G Coulter¹, Joseph G Jacangelo³, Kellogg J Schwab⁴

Affiliations

¹ Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
² JHU/MWH Alliance, Johns Hopkins University, Baltimore, MD, USA.
³ Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; JHU/MWH Alliance, Johns Hopkins University, Baltimore, MD, USA; MWH-Stantec, Pasadena, CA, USA.
⁴ Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; JHU/MWH Alliance, Johns Hopkins University, Baltimore, MD, USA. Electronic address: kschwab1@jhu.edu.

PMID: 29407643
DOI: 10.1016/j.watres.2018.01.053

Abstract

Noroviruses cause significant global health burdens and waterborne transmission is a known exposure pathway. Chlorination is the most common method of disinfection for water and wastewater worldwide. The purpose of this study was to investigate the underlying causes for discrepancies in human norovirus (hNoV) resistance to free chlorine that have been previously published, and to assess hNoV GI and GII persistence during disinfection of municipal secondary wastewater (WW) effluent. Our results reveal that choice of hNoV purification methodology prior to seeding the viruses in an experimental water matrix influences disinfection outcomes in treatment studies. Common hNoV purification processes such as solvent extraction and 0.45-μm filtration were ineffective in removing high levels of organics introduced into water or wastewater samples when seeding norovirus positive stool. These methods resulted in experimental water matrices receiving an additional 190 mg/L as Cl₂ of 15-s chlorine demand and approximately 440 mg/L as Cl₂ of 30-min chlorine demand due to seeding norovirus positive stool at 1% w/v. These high organic loads impact experimental water chemistry and bias estimations of hNoV persistence. Advanced purification of norovirus positive stool using sucrose cushion ultracentrifugation and ultrafiltration reduced 15-s chlorine demands by 99% and TOC by 93% for loose (i.e. unformed diarrhea) stools. Using these methods, hNoV GI and GII persistence was investigated during free chlorination of municipal WW. A suite five of kinetic inactivation models was fit to viral reverse transcription-qPCR reduction data, and model predicted CT values for 1, 2, and 3 log₁₀ reduction of hNoV GI in municipal WW by free chlorine were 0.3, 2.1, and 7.8 mg-min/L, respectively. Model predicted CT values for reduction of hNoV GII in WW were 0.4, 2.0, and 7.0 mg-min/L, respectively. These results indicate that current WW treatment plant disinfection practices employing free chlorine are likely protective for public health with regards to noroviruses, and will achieve at least 3-log reduction of hNoV GI and GII RNA despite previous reports of high hNoV resistance.

Keywords: Chlorination; Norovirus; Stool purification; Wastewater; Water treatment.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Chlorine / pharmacology*
Disinfection / methods
Halogenation
Norovirus / drug effects*
Norovirus / genetics
RNA, Viral / drug effects
Real-Time Polymerase Chain Reaction
Waste Disposal, Fluid / methods
Wastewater / virology*
Water Pollutants

Substances

RNA, Viral
Waste Water
Water Pollutants
Chlorine