POTATO STARCH AS A SLUDGE CONDITIONER

■TTHE main source of ground water X in Florida is the "principal artesian aquifer/' also referred to as the "Floridan aquifer." It includes permeable and solution-riddled limestones and dolomites of the Middle Eocene (Avon Park and Lake City), Upper Eocene (Ocala limestones), Oligocene (Suwannee limestone), and Miocene (Tampa limestones and permeable sediments of the Hawthorn formation in hydrologic contact with the aquifer) periods. The Floridan aquifer is covered in great portions of the state by confining beds of marls, clays and clayey sand, and shells. These beds also form the base of shallow ground water, including the Biscayne aquifer, the principal source of water in southeastern Florida. The shallow ground water is a source of supply in the coastal lowlands where the Floridan aquifer yields highly minralized water. The water stored in these limestone aquifers, much of it under artesian pressure, constitutes one of the largest and most productive ground water reservoirs in the world. It is not surprising, therefore, that Florida is a typical well-water state and that more than 90 per cent of its public water supplies are derived from wells. Because of the solubility of both calcium and magnesium carbonates in water containing carbon diooxide, most of Florida's ground water supplies may be classified as medium hard to hard, a d Florida is listed by USGS as one of the hard water states of the nation. It is the only one of the eighteen southern states so classified. Wells deriving water from the older formations, primarily the Ocala Eocene limestone, contain substantial amounts of both calcium and magnesium hardness, although in practically every case calcium hardness predominates. However, as will be shown later, wells deriving their water from more recent