Assessing Iron (II) and Fluoride Removals by Indigenously Fabricated Household Water Filter of North Guwahati

Groundwater is the major source of water for domestic purposes in Amingaon, North Guwahati, Assam which is contaminated with high concentrations of iron and fluoride. The household-level treatment for iron removal includes the use of indigenously fabricated water filter units comprising sand, gravel, and wooden charcoal. The filter media are arranged in layered form in RCC rings, tin containers, and plastic buckets. The RCC filter unit is the most commonly used, especially for iron removal. However, the contamination level of groundwater of Amingaon and the effectiveness of indigenously fabricated household filter units in iron and fluoride removal is neither estimated/evaluated by government agencies nor reported in the literature. The present study aims to investigate the level of contamination of groundwater for iron and fluoride as well as efficiency and effectiveness of an RCC filter unit in the removal of iron and fluoride over a period of 6 months. The groundwater in and around the IIT Guwahati campus has a high concentration of iron (0–11.3 mg/L) whereas the concentration of fluoride is in the range 0.13–0.66 mg/L. A set of two samples, one from the tube well and the other from the filtered water, was collected at an interval of 3 days from a selected household RCC filter. Water quality parameters, viz., iron, fluoride, pH, temperature, conductivity, turbidity, and dissolved oxygen were estimated for the collected samples of each set. The selected RCC filter unit is able to produce filtered water containing residual iron concentration of 0–0.08 mg/L from an initial iron concentration of 8.13–11.63 mg/L. The selected filter unit is also able to reduce the fluoride concentration from a value of 0.51–1.17 mg/L to 0.39–0.77 mg/L. The DO level in the groundwater increases as the same is poured into the filter unit thereby converting ferrous iron to ferric form. The ferric form of iron is filtered out as precipitate in the filter unit.