Enteroviruses in sewage: comparison of different technologies for wastewater treatment and reuse

Seven wastewater treatment plants were twice sampled to compare their different technologies for the removal of enteroviruses. These technologies are extended aeration, oxidation ditch, stabilization pond, aerated stabilization pond, submerged fixed film reactor, trickling filter and trickling filter followed by activated sludge in El-Serw, El-Rahamna, El-Adliya, Daqahla, El-Barashiya, Sohag and El-Fayoum wastewater treatment plants, respectively. Virus counts of raw sewage ranged between 2.7 x 10(3) and 20 x 10(3) PFU/L and for treated effluents was between 0 and 6 x 10(3). The percentage of virus removal was varied where trickling filter and tickling filter followed by activated sludge reduced virus counts by 95.7 and 99.9, respectively. Extended aeration removed 64.2%, oxidation ditch 66.5%, stabilization pond 44.9%, aerated stabilization pond 13.34%, and submerged fixed film reactor removed 53.4%. The neutralization test revealed five types of enteroviruses, poliovirus types 1,2 and 3 and Coxsackievirus types B4 and B5. The isolated polioviruses were vaccine strains. From the frequency distribution of the detected viruses, poliovirus type 2 was the most dominant.