Abstract

The occurrence of elevated concentration of Fluoride, Hardness and Heavy metals in ground water has drawn worldwide attention because it has considerable impact on human health. Recent studies also suggested these elements in groundwater can be reasons for the chronic kidney disease of unknown etiology (CKDu) issue in dry zones in Sri Lanka. Groundwater sampling was conducted in 1,262 sampling wells distributed in all administrative districts and all climatic zones in Sri Lanka. Concentration of 18 water quality parameters including natural mineral ions and heavy metal ions were measured. In many dry zonal districts of Sri Lanka, fluoride and hardness levels exceed desirable levels. Spatial variations in groundwater quality in Sri Lanka were evaluated using multivariate statistical analysis techniques. Sampled wells were clustered into two different clusters based on the similarity of the groundwater quality parameters. Type of aquifer they are located has been significantly influenced on the clustering. Further, 6 factors which may influence on groundwater quality of Sri Lanka were also identified in the factor analysis. The main factors were natural rock-water interactions, pollution caused by industrialization and waste discharge, agrochemical usage and infiltration of storm water rich in lead into shallow aquifers. It was evaluated the possibility of removing fluoride and hardness from groundwater using carbon electrolysis technique and Chicken Bone Char (CBC) filtration. Under different initial total hardness values, CBC filtration removed over 99% of fluoride while carbon electrolysis removed up to 87% maximum. Electrolysis and CBC filtration respectively exhibited a removal of total hardness up to 99% and 54%, under different initial hardness values. Since these two techniques are capable of removing fluoride and hardness effectively, a hybrid continuous flow system which consists of both the treatment processes can be developed to ensure the best treatment.