Indigenous Household Groundwater Filter Unit of North Guwahati (Assam) for Iron and Fluoride Removals

The rural population of Amingaon, North Guwahati (Assam) relies heavily on groundwater for their domestic needs. But groundwater is reported to be contaminated with excessive amounts of iron and fluoride. The population uses indigenous household groundwater filter units for iron removals. These units are fabricated using reinforced cement concrete (RCC) circular pipes, tin containers, and plastic buckets with river sand, wooden charcoal (in some cases), and gravel serving as filtering media either in layered or mixed form. The present work aims to review and document the different types of indigenous household groundwater filter units being used in this area. In addition, efforts are also made to evaluate the performance of a selected filter unit for iron and fluoride removal from the groundwater. The iron concentration in groundwater of Amingaon, North Guwahati varies from 0 to 11.03 mg/L exceeding the permissible limit for drinking water (0.3 mg/L), whereas fluoride concentration varies from 0.10 to 0.68 mg/L-always meeting the permissible limit 1.5 mg/L. A selected indigenous household groundwater filter unit is monitored to assess its performance over a period of 86 days. The filter unit is found to be highly effective in iron removal of 99% or more from an initial concentration of 1.33-2.08 mg/L down to 0-0.2 mg/L meeting the limit of drinking water quality. The iron removal is mainly due to increase in DO levels which precipitates out the iron and the precipitated iron is filtered out through the filter unit. The concentration of fluoride in the groundwater is not exceeding the permissible limit of 1.5 mg/L. Fortunately, the filter unit is not reducing the fluoride concentration present in the groundwater.