Measurement of optical turbidity of drinking water samples, using nephelometric and laser light techniques

Abstract

The specific objective of this study was to directly measure drinking water turbidity of six (6) groundwater samples of surface rivers, streams and hand-dug wells from Ghana, for sustainable national development. These measurements were carried out in two research laboratories by using laser light techniques of light scattering and light transmission experiments to assist nephelometric measurements. The nephelometric studies showed a strong positive correlation with a R2 value of 0.9285 between optical turbidity (NTU) and the concentration of the suspended solids (mg/L) of the water samples. Thus, indicating that environmental conditions do affect water turbidity and suspended solids. Furthermore, polar diagrams of light scattered by high turbidity and low turbidity water samples could be distinguished. Indeed, the polar graphs of all the drinking water samples were noticeably the same shape for the most turbid to the least, for the measuring light wavelength λ=633 nm (in air). The study also showed that light transmission measurements can be used to complement the fractional reduction in light intensity per metre length due to scattering of the inhomogeneities in the water samples