One of the most persistent problems facing the water treatment industry today is the occurrence of fouled heat transfer surfaces.  Crystallization of inorganic salts having inverse solubility is one of the most common reasons for this phenomenon.  Part 1 of the paper overviews the topic of crystal structure where concepts of a crystal lattice, coordination principle, ionic radii and miller indices are explained.  Part 2 of the article deals with crystal structure in terms of water treatment applications.  Calcium carbonate (calcite, aragonite) and calcium sulfate (for gypsum, anhydrite) are discussed in detail along with the concept of applying crystal modifiers to inhibit scale formation in cooling waters

86-06: The Importance of Crystal Structure to the Water Treatment Industry