TP22-10: Interpreting and Applying Scale Indices and Saturation Ratios to Identifying and Solving Water Treatment Challenges

Predictive models and tests have evolved significantly since the marble test of the early twentieth century, the simple driving force indices such as the father of all indices, the Langelier Saturation Index1 in the 1930s, through the early speciation engines of the 1970s and 1980’s, 2,3,4 and onto the high ionic strength models of the twenty first century.5,6 Other models such as the Calcium Carbonate Precipitation Potential7 and Momentary Excess,8 predict the quantity of scale precipitation that might be expected. The derivation of predictive indices can range from a simple index, to sophisticated, more general indices employing state-of-the-art corrections for temperature, activity, and ion pairing.