Concentration of viruses from tap water and sewage with a charge-modified filter aid

Positively charged microporous filters have been shown to have definite advantage over negatively charged filters for concentrating viruses from water as they eliminate the need of water conditioning (acidification and multivalent cation addition) prior to filtration. The present study was designed to evaluate the use of a charge-modified (Zeta plus) filter aid (AMF CUNO, Meriden, CT) for the concentration of viruses (Poliovirus-1, Coxsackievirus B-3 and ECHO virus-7) from large volumes of tap water. Charge-modified filter aid could efficiently adsorb polio, coxsackie and ECHO viruses from water. The adsorbed viruses from both tap water and secondary sewage were most efficiently eluted with 4% beef extract - 0.5 M NaCl, pH 9.5. The efficiency of recovery of poliovirus, coxsackievirus and ECHO virus from 10- to 20-1 vols, of tap water ranged between 32 and 98%, 67 and 100% and 69 and 100%, respectively. This technique appears to have distinct advantages over previous methods as it requires low cost equipment (47 mm polypropylene filter housing) and materials, is simple and easy to handle, can filter large volumes of water (≥20 l) with good recoveries at ambient pH and can be efficiently used to monitor viral water quality.