Other Methods of Water Treatment

• Lime Softening adds hydrated lime in order to precipitate out hardening agents such as calcium carbonate and magnesium. These materials are then removed by sedimentation or filtration.

• Ion Exchange includes cation and anion exchange. Cation exchange is used for water softening whereby the hardness-causing ions such as calcium and magnesium are exchanged with sodium ions. It is also used for removing radium. Anion exchange is used for nitrate and uranium removal. It can also be used for arsenic removal, depending on the arsenic species present and source water quality

• Reverse Osmosis (RO) is the process where water containing a high concentration of solids is pumped under pressure through a semipermeable membrane. The water that has passed through the membrane is low in solids, leaving behind a waste stream high in solids. Reverse osmosis is quite effective at removing most inorganic contaminants. Membranes with larger pore openings are available to reduce the cost of treatment when the solids content of the water to be treated is lower

• Aeration mixes water with air in a chamber or tower filled with packing material to disperse the water, allowing for sufficient contact time. As the water trickles down over the material, air is passed upward, removing the contaminants from the water. Aeration is effective at removing volatile organic compounds.

• Granulated Activated Carbon (GAC) beds adsorb organic contaminants as the water passes through them. In some cases, this process is used in conjunction with aeration to increase the effectiveness of the organic chemical removal.