Silica reduction via lime treatment of brine concentrates
In desalination of brackish water, silica is one of the major foulants that can form on the reverse osmosis membranes and limit the water recovery. In addition, it is a very adherent scale. Once it forms, it is very difficult to clean and cleaning may damage the membrane. Pretreatment is used as a measure to reduce silica levels in the feed and hence mitigate silica fouling. This research examines silica removal by lime in laboratory tests using reverse osmosis concentrate from a 22 GPM pilot plant. In one treatment scheme, RO concentrate was treated with nano filtration, then the concentrate and the permeate were subjected to lime treatment and evaluated from the standpoint of silica removal. In another scheme, the nano-permeate was treated with additional RO and that concentrate was treated with lime. The effect of chemical treatment on different parameters like hardness, alkalinity, and pH was also studied. The results showed that lime treatment was very effective for removing silica from all of the concentrate streams and the removal could be described by first-order reaction. Economic analysis showed that lime treatment may be a cost-effective method for handling concentrate from membrane processes during inland desalination applications.
Kolluri, Bhaskar Sai, "Silica reduction via lime treatment of brine concentrates" (2003). ETD Collection for University of Texas, El Paso. AAIEP10572.