Influence of wastewater treatment process and the population size on human virus profiles in wastewater

Human adenovirus (AdV and AdV species F), enterovirus (EV) and norovirus (NoV) concentrations entering wastewater treatment plants (WWTP) serving different-sized communities, and effectiveness of different treatment processes in reducing concentrations were established. Data was combined to create a characteristic and unique descriptor of the individual viral composition and termed as the sample virus profile. Virus profiles were generally independent of population size and treatment process (moving bed biofilm reactors, activated sludge, waste stabilisation ponds). AdV and EV concentrations in wastewater were more variable in small (<4000) and medium-sized (10,000-64,000) WWTP than in large-sized (>130,000 inhabitants) plants. AdV and EV concentrations were detected in influent of most WWTP (AdV range 1.00-4.08 log(10) infectious units (IU)/L, 3.25-8.62 log(10) genome copies/L; EV range 0.7-3.52 log(10) plaque forming units (PFU)/L; 2.84-6.67 log(10) genome copies/L) with a reduced median concentration in effluent (AdV range 0.70-3.26 log(10) IU/L, 2.97-6.95 log(10) genome copies/L; EV range 0.7-2.15 log(10)PFU/L, 1.54-5.28 log(10) genome copies/L). Highest culturable AdV and EV concentrations in effluent were from a medium-sized WWTP. NoV was sporadic in all WWTP with GI and GII concentrations being similar in influent (range 2.11-4.64 and 2.19-5.46 log(10) genome copies/L) as in effluent (range 2.18-5.06 and 2.88-5.46 log(10) genome copies/L). Effective management of WWTP requires recognition that virus concentration in influent will vary - particularly in small and medium plants. Irrespective of treatment type, culturable viruses and NoV are likely to be present in non-disinfected effluent, with associated human health risks dependent on concentration and receiving water usage.