LOW-LEVEL TURBIDITY MEASUREMENTS : A COMPARISON OF INSTRUMENTS

Measure the effect of turbidimeter design and calibration method on instrument variability at low turbidity values. Using six-bench top and four portable turbidimeters with four calibration materials to measure turbidity of monthly samples collected from 10 distributed treatment plants. Results indicated two groups of instruments. Instruments automatically set or do not automatically set the low-particle readind at either zero or 0,2 ntu.