Assessment of an electropositive granule media filter for concentrating viruses from large volumes of coastal water

Occurrence of human enteric viruses in coastal water poses a high public health risk upon exposure for swimmers. However, it is difficult to detect viruses directly due to their low concentrations in the coastal water; this demands concentration of adequate amounts of viruses from large volumes of coastal water before viral detection. Here, we explored a filter cartridge system with electropositive granule media (EGM) for recovery of viruses from coastal water for the first time. The viruses were assayed by TaqMan-based quantitative PCR (qPCR). To optimize the tool, operational parameters of the EGM filter and the effect of coastal water quality on virus recovery were investigated. Furthermore, the filter's effectiveness was validated by analyzing the recovery of various enteric viruses and comparing the recovery rates with those of tangential flow filtration (TFF). The EGM filter could recover more than 88% of the enteric viruses including astroviruses (AstVs), noroviruses (HuNoVs GII) and adenoviruses (HAdVs) from coastal water with the established optimal protocol in comparison with TFF (52.5%). Recovery rates remained high under varied coastal water quality conditions including pH (5 to 9), temperature (4 to 32 degrees C), chemical oxygen demand level (CODMn) below 4 mg L-1, ammonium concentration (NH3-N) below 2 mg L-1, and viral loads below 10(12) GCs. The findings suggest that the EGM filter provides an efficient approach for concentrating viruses from large volumes of coastal water (ranging from 10 L to 100 L), which can be a useful tool in monitoring sparsely existing viruses in coastal water.