Main Factors Affecting the Photographic Determination of the Turbidity and Chromaticity of Water

Abstract

The main factors that affect the performance characteristics of determining the turbidity and chromaticity of water by digital colorimetry in field (on-site) are studied. The test samples are suspensions of formazine and solutions composing the dichromate–cobalt chromaticity scale, which are used for calibration in standardized spectrophotometric methods for monitoring water quality. The affecting factors include the geometry of the vessel for colorimetric samples, the manufacturing quality of the adjustment device (drawing of chess fields), the method of fixing the camera in shooting, the method of performing the blank experiment, the illumination of the sample in shooting, the degree of cropping of the edges of the photograph of the chess fields in its digital processing, camera specifications, and the mutual effect of chromaticity and turbidity on the contrast of the photograph and its mean-root-square brightness. It is demonstrated that for the design of the on-site photographic measurements it is enough to have a digital camera, an adjustment device, and a measuring vessel. Photographing can be done with a camera held in hands. An empty measuring vessel may be used as an optically transparent sample for the blank experiment. Recommendations have been developed on optimizing the photographic measurements of turbidity and chromaticity. A possibility of the simultaneous determination of turbidity and chromaticity is shown by the example of monitoring the quality of tap water.