Laboratory and Field Studies to Assess the Effect of Hydrogeological Parameters on Coliform Removal During Riverbank Filtration

Essential hydrogeological parameters related to riverbank filtration, such as grain size (D50) of aquifer soils, hydraulic gradient, bed height, fine content, as well as operation and detention period, were explored in laboratory column studies to determine critical percentage total coliform removal. Increases in total coliform removal efficiency were seen for both in situ aquifer soil and altered aquifer soils as detention and operating period increased. With an increase in detention and operation period from 1 to 72 h, the percentage total coliform removal for aquifer soil increased from 42.5% to 94.3% and 10.4% to 77.11%, respectively. The removal of total coliform increased from 94.3% to 99.9% as the percentage fine content increased from 2.5% to 15%, increased from 94.3% to 98% as the hydraulic gradient decreased from 1.45 to 1.1. An increase was noticed from 73.1% to 95.9% as the mean grain size decreased from 3.2 to 0.22 mm. The importance of hydrogeological parameters impacting coliform removal was demonstrated using multiple linear regression analysis. Detention period and percentage of fine content were directly proportional to total coliform removal effectiveness among various hydrogeological parameters, but percentage total coliform removal was inversely proportional to hydraulic gradient as well as to mean grain size. The model was validated using field study data from the riverbank filtration located on the Rushikulya River, which yielded excellent results, ensuring the accuracy of the model produced. The Badamadhapur riverbank filtration facility was also shown to be effective in removing total coliform pathogens.