Removal of indigenous coliphages and enteric viruses during riverbank filtration from highly polluted river water in Delhi (India)

Emerging countries frequently afflicted by waterborne diseases require safe and cost-efficient production of drinking water, a task that is becoming more challenging as many rivers carry a high degree of pollution. A study was conducted on the banks of the Yamuna River, Delhi, India, to ascertain if riverbank filtration (RBF) can significantly improve the quality of the highly polluted surface water in terms of virus removal (coliphages, enteric viruses). Human adenoviruses and noroviruses, both present in the Yamuna River in the range of 10⁵ genomes/100 mL, were undetectable after 50 m infiltration and approximately 119 days of underground passage. Indigenous somatic coliphages, used as surrogates of human pathogenic viruses, underwent approximately 5 log₁₀ removal after only 3.8 m of RBF. The initial removal after 1 m was 3.3 log₁₀, and the removal between 1 and 2.4 m and between 2.4 and 3.8 m was 0.7 log₁₀ each. RBF is therefore an excellent candidate to improve the water situation in emerging countries with respect to virus removal.