title: A case study of enteric virus removal and insights into the associated risk of water reuse for two wastewater treatment pond systems in Bolivia.
abstract: Wastewater treatment ponds (WTP) are one of the most widespread treatment technologies in the world; however, the mechanisms and extent of enteric virus removal in these systems are poorly understood. Two WTP systems in Bolivia, with similar overall hydraulic retention times but different first stages of treatment, were analyzed for enteric virus removal. One system consisted of a facultative pond followed by two maturation ponds (three-pond system) and the other consisted of an upflow anaerobic sludge blanket (UASB) reactor followed by two maturation (polishing) ponds (UASB-pond system). Quantitative polymerase chain reaction with reverse transcription (RT-qPCR) was used to measure concentrations of norovirus, rotavirus, and pepper mild mottle virus, while cell culture methods were used to measure concentrations of culturable enteroviruses (EV). Limited virus removal was observed with RT-qPCR in either system; however, the three-pond system removed culturable EV with greater efficiency than the UASB-pond system. The majority of viruses were not associated with particles and only a small proportion was associated with particles larger than 180 μm; thus, it is unlikely that sedimentation is a major mechanism of virus removal. High concentrations of viruses were associated with particles between 0.45 and 180 μm in the UASB reactor effluent, but not in the facultative pond effluent. The association of viruses with this size class of particles may explain why only minimal virus removal was observed in the UASB-pond system. Quantitative microbial risk assessment of the treated effluent for reuse for restricted irrigation indicated that the three-pond system effluent requires an additional 1- to 2-log10 reduction of viruses to achieve the WHO health target of <10(-4) disability-adjusted life years (DALYs) lost per person per year; however, the UASB-pond system effluent may require an additional 2.5- to 4.5-log10 reduction of viruses.
authors.affiliation: University of South Florida, College of Marine Science, 140 7th Avenue South, St. Petersburg, FL, USA. Electronic address: esymonds@mail.usf.edu.
authors.forename: E M
authors.initials: EM
authors.lastname: Symonds
authors.affiliation: University of South Florida, Department of Civil & Environmental Engineering, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: verbylam@mail.usf.edu.
authors.forename: M E
authors.initials: ME
authors.lastname: Verbyla
authors.affiliation: Biological Consulting Services of North Central Florida, Inc., 4609-A NW 6th Street, Gainesville, FL, USA. Electronic address: lukasik@microbioservices.com.
authors.forename: J O
authors.initials: JO
authors.lastname: Lukasik
authors.affiliation: University of South Florida, Department of Mathematics and Statistics, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: rckafle@shsu.edu.
authors.forename: R C
authors.initials: RC
authors.lastname: Kafle
authors.affiliation: University of South Florida, College of Marine Science, 140 7th Avenue South, St. Petersburg, FL, USA. Electronic address: mya@usf.edu.
authors.forename: M
authors.initials: M
authors.lastname: Breitbart
authors.affiliation: University of South Florida, Department of Civil & Environmental Engineering, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: jm41@usf.edu.
authors.forename: J R
authors.initials: JR
authors.lastname: Mihelcic
mesh_terms: D057914:Agricultural Irrigation; D000818:Animals; D001838:Bolivia; D002460:Cell Line; D002522:Chlorocebus aethiops; D004770:Enterovirus / Q000235:genetics / Q000302:isolation & purification*; D010316:Particle Size; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018570:Risk Assessment; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000821:virology*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D062065:Wastewater
keywords: Norovirus; Pepper mild mottle virus; Rotavirus; Sanitation; Stabilization pond; Upflow anaerobic sludge blanket reactor