Concentration of natural radionuclides in raw water and packaged drinking water and the effect of water treatment

The Raw Water (RW) collected from natural sources are subjected to water treatment process including Reverse Osmosis, and are packed in bottles as packaged drinking water (PDW). Raw water (21 nos) taken from deep wells of Chennai and Secunderabad which are used in the production of packaged drinking water, were analysed for ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb concentration levels. Concentration levels of ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra, ²¹⁰Pb and ²¹⁰Po in packaged drinking water were also analysed. Uranium was chemically separated using anion exchange method and the activity was estimated by alpha spectrometry. ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in the water samples were pre-concentrated by passing through manganese impregnated acrylic fibre. ²²⁶Ra was estimated by emanometry method and counted in alpha counting system. ²²⁸Ra and ²¹⁰Pb was chemically separated and counted in low background beta counting system. The mean concentrations of ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra, and ²¹⁰Pb in Raw water (RW) at Chennai were found to be 12.1, 1.3, 7.1, 2.6, 27.5, and 16.3 mBq/L respectively. The mean concentrations of ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in RW at Secunderabad were found to be 40.9, 1.7, 41.5, 84.5, 100.1, and 17.0 mBq/L respectively. The mean concentrations of ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in PDW at Chennai were found to be ≤ 1.3, ≤ 1.3, ≤ 1.3, ≤ 0.2, ≤ 1.7 and 28.0 mBq/L. The mean concentrations of ²³⁴U, ²³⁵U, ²³⁸U, ²²⁶Ra, ²²⁸Ra, and ²¹⁰Pb in PDW at Secunderabad were found to be ≤ 1.3, ≤ 1.3, 1.7, 4.3, 5.0 and 28.1 mBq/L. The study indicated a considerable reduction in the concentration of natural radionuclides due to water treatment. (author)