EDGE DETECTION TECHNIQUE FOR SIMULTANEOUS MEASUREMENT OF TOTAL SUSPENDED SOLIDS AND TURBIDITY

Abstract

APHA Standard methods 2130B and 2540D have proven valid and reliable methods to determine turbidity and total suspended solids (TSS). However, both methods have drawbacks and limitations. Carcinogenicity of formazin, inconsistency in preparation, and interference are the primary concerns in turbidity measurement. Equipment complexity, working steps, and measurement time are primary concerns in TSS measurement. The edge detection technique (EDT) is an alternative to overcome the drawbacks and limitations. This research aims to conduct the performance test of the proposed method using pro-analytical grade kaolin (Sigma-Aldrich K7375), which has non-toxic properties compared to the formazin standard. Natural water samples from three different sampling locations became another subject in the EDT-based measurement method performance test. Steps included are elemental characterization with SEM-EDS-JEOL-JSM6510LA and particle size analysis with zeta sizer Horiba SZ-100. Turbidity measurement with Eutech TN100 and the TSS measurement with the gravimetric approach. Counted particle (CP) measurement through the EDT compared with the standard measurement. It showed that kaolin characteristics are closer to the natural suspension indicated by the more identical elemental compositions than the formazin elemental characteristics. Another result showed a correlation between kaolin concentration (KC), turbidity level, TSS concentration, and the counted particle is > 0.9. The proposed approach showed promising results indicated by the % Relative Standard Deviation < 20% for KC 0.5-20 mg/L and < 40% for KC 40-100 mg/L, in the linear range of 0.5-100 mg/L. Using a sample cell with a flat surface may improve the performance of the proposed approach. It is thus possible to reduce the reflection of light, which is a noise source in the measurement result.