Drinking Water

Impact of pit-toilet leachate on groundwater chemistry and role of vadose zone in removal of nitrate and E. coli pollutants in Kolar District, Karnataka, India

Impact of pit-toilet leachate on groundwater chemistry and role of vadose zone in removal of nitrate and E. coli pollutants in Kolar District, Karnataka, India

Author : M Sekhar, PV Raghuveer Rao, Sudhakar M Rao
View of the town of Mulbagal, Karnataka
Percentage of wells exhibiting greater than permissible levels of contaminants

Analysis indicates that 'rock weathering mechanism controls the chemistry of groundwater outside the town (PHS samples), while, evaporation-crystallization controls the chemistry of groundwater inside the town (ITS samples)'.
The study also looks at the efficacy of the vadose zone in the removal of pollutants. The vadose zone is the soil layer between the land surface and the top of the water level. It found that wells with water table depths of 25m or greater are free from E-coli contamination.

Conclusions:


The higher levels of contamination in wells inside the town and data analysis prove that leachate infiltration from pit toilets is the primary source of contaminants. On the other hand, rock weathering is the primary source in areas outside the town. The paper also proved that the vadose zone facilitates removal of Ecoli and of nitrates.

Previously published in the Environmental and Earth Science Journal, DOI 10.1007/s12665-012-1794-9

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