Application of pellet softening (PS) as a scale prevention method in seawater desalination plants

This research investigates the potential of pellet softening (PS) on calcite particles as a control method to avoid scaling of calcium carbonate from seawater in desalination. Experimental studies were conducted in a 5 L agitated vessel under controlled temperature and agitation. The measured transient calcium ion concentration, salinity, pH, and total alkalinity of seawater during mixing with calcite particles show that the Ryznar Stability index (RSI) increased from 4.3 to 5.7, which means that the status of seawater changed from high scaling potential to low scaling potential after being subjected to PS process at 70 degrees C. The supersaturation of seawater with respect to calcite is reduced from 33.5 to 5.27. The results demonstrate that PS is a feasible and effective pretreatment strategy for thermal and membrane seawater desalination facilities.