Performance evaluation of riverbank filtration scheme

摘要

This article presents an analytical method to determine the distance of a bank filtration well from a river in commensuration with the desired percentage of bank filtrate and removal of pathogenic compounds. Applying least squares optimization technique using Marquardt algorithm, the unknown parameter, distance of the well from the river has been estimated. The travel time in commensuration with the desired percentage removal of pathogenic compounds has been ascertained using the first-order decay equation. For evaluating effectiveness of the technique, the physico-chemical and biological parameters of extracted bank filtrate from 22 wells located in the vicinity of the River Ganga and the Upper Ganga Canal network at Haridwar have been analysed for the non-monsoon and the monsoon periods. The physicochemical parameters of the extracted water showed concentration much below the acceptable limits, except turbidity. The percentage removal of turbidity in the extracted water was found about 98 and 76 during the monsoon and non-monsoon periods respectively, in comparison to water from the river/canal. The count of biological parameters, viz. total coliform and faecal coliform in the extracted water is removed considerably (65% to 85%), but is found above the acceptable limit. The reason could be mixing of bank filtrate with the rich constituents in the groundwater. It is suggested that bank filtration dilutes groundwater quality and can be regarded as a technique to conjunctive management of surface and groundwater quality.