Local technologies for removal of hardness in groundwater.

Abstract

Groundwater is the major natural resource in Jaffna peninsula and it is used for all purposes. Jaffna peninsula is underlain by a Miocene limestone aquifer which is the main source for hard water. Considering problems of water hardness its removal is essential to prevent from health hazards and to get soft tasty drinking water. Five treatments were selected during the preliminary test as 30 minutes boiling, four hours aeration, overnight aeration, two hours aeration plus ten minutes boiling and electrocogulation running time for 20 minutes. Different hardness content groundwater sources were selected. Raw water samples and treated water samples were analysed for pH, electrical conductivity, chloride, alkalinity and hardness. Aluminium residue also was checked to electrocoagulated water. Raw water hardness was varied from 244 mg/l to 883 mg/l but the SLS maximum desirable level is 250 mg/l which express the severity of the hardness problem. Very low average reduction of 36.7% was got in electrocogulation but it is mostly suitable for high degree of hardness area. The reduction range varied from 10.7 to 68.2% in four hours aeration. The reduction percentage was greater than 40 to 80% of the selected well in overnight aeration. Reduction pattern is nearly equal to boiling and two hours aeration plus ten minutes boiling. Highest average percentage reduction of 56.5 was achieved in boiling. The reduction level was higher than other treatment in boiling to 65% of the selected well water. In addition to hardness test chloride, alkalinity was not significantly changed to treated and fresh raw water. Treated water alkalinity and electrical conductivity were less than raw water. Boiling and boiling with aeration were selected as a suitable treatment to most of the area water and boiler was design without evaporation loss of water. The 50% of hardness was reduced by designed filter. Design filter can be used as domestic treatment to get soft water with low cost.