Abstract
Turbidimeters are frequently used as one of the methods to measure continuously the amount of suspended solids (SS). In practical use, wastewater is mostly colored according to its properties. In this study, changes of the turbidimeter indications due to the coloring of dispersant in suspensions were examined under various conditions by changing such facters as optical methods, the particle sizes, the concentrations of SS and coloring matters. The following three optical methods were adopted to measure SS ; (a) measuring the scattered light flux with an integrating sphere (method A), (b) measuring the ratio of scattered light flux to total light flux with an integrating sphere (method B), (c) measuring the ratio of scattered light flux to transmitted light flux without integrating sphere.
1) The method A shows the largest change in those three methods, but the method B is scarcely influenced by the coloring of dispersant. The method C shows little change for coloring suspensions whose spectral transmittances are not dependent on wavelength.
2) The effect of the coloring of dispersant appears more clearly in case of more dilute concentration of SS and larger particle size.
3) The suspensions colored by methylene blue show a larger change in the indication than that by eosin.
