AN ANALYSIS OF LOW-LEVEL TURBIDITY MEASUREMENTS

The turbidity measurement is the most widely used method for monitoring the performance and the particle-removal efficiency of water filtration systems. But the instrument design specifications used in standardized methods for turbidity measurement are antiquated. This study, which compared ratio- and nonratio-type turbidimeters, showed that even when turbidimeter design meets instrument design specifications given in Standard Methods and when each instrument has been calibrated according to the manufacturer's manual, the same reading may not be obtained for a given suspension. Further study is needed to compare the results from the two types of instruments using a large sampling of low-turbidity, filtered-water samples from plants across the United States. In addition, the use of performance standards for turbidimeter design and calibration should be considered. With this two-pronged approach, new techniques could be developed and innovation in instrument design would be promoted.