Abstract:
Many highly populated cities and towns in India are situated on riverbanks and have favourable hydrogeologic conditions necessary for the natural and cost-effective process of River Bank Filtration (RBF). Two drinking water production wells were selected in Haridwar by the river Ganga to monitor the quality of bank filtrate abstracted in the period 2005-2006. Two monitoring wells were also installed and their water quality was analysed. The physico-chemical instant parameters and turbidity were determined in the field on a monthly basis in pre-monsoon season and every two weeks in monsoon season. The major cations and anions, and bacteriological indicator parameters were analysed in the laboratory. Results show that the parameters investigated for production well water are within permissible limits for drinking water according to WHO and BIS 10500 (1991), except coliform counts. As a result of RBF, total coliforms and faecal coliforms have been removed by 99% to
99.9% respectively in the abstracted bank filtrate. The turbidity is reduced by up to 99.9%. Though during RBF there is an improvement of water quality, it is essential to develop a physical model for the dynamic simulation of flow and transport. The main focus of the applied water quality model has been the dynamic river—aquifer interactions based on the effects of fl uctuating river levels. These fluctuations have been relevant for clogging processes as these destabilise the clogged layer. At the RBF site in Haridwar, the extent of clogging is observed to be limited to only few centimetres and water quality simulations indicate a very limited role of the layer in travel zone. However, with the increase in clogged layer, its role on further quality simulation cannot be always over looked.
