Predicting calculating scaling tendency in membrane plants

Predicting scale formation in desalination plants is a matter of a number of calculations. The accuracy of these calculations is dependent on accurate data, and representative operating conditions. These calculations are normally carried out by using software, supplied either by the membrane manufacturers or by antiscalants manufacturers. Often the user will accept the results without question, and without fully understanding their meaning or the methods and assumptions used to generate the results. The paper outlines the steps that the software undertakes to reach its results. It will also show the sensitivity of the results to the accuracy of the initial data, and the value of having a complete water analysis. The paper will also outline some of the common errors made when using scale prediction software. It will also introduce the use of calcium carbonate precipitation potential (CCPP) as a method of predicting scale, and linking this with the dose rate of antiscalant.