Alginates for corrosion and scale control

Provided herein are methods for inhibiting the formation of scale on equipment in contact with a produced fluid containing a scale-forming divalent cation. Such methods can comprise adding an activated alginate to the produced fluid in an amount effective to react with 5 the divalent cation in the produced fluid to form an activated alginate complex; and separating the activated alginate complex from the produced fluid. Methods can further comprise recycling the activated alginate from the activated alginate complex by dissolving the activated alginate complex. The activated alginate can be prepared by thermally modifying an alginate precursor at a temperature of from 80°C to 180°C for a period of at least 24 hours. The 10 activated alginate can be in the form of a solution including 0.1% to 10% by weight activated alginate, based on the total weight of the solution. The activated alginate can exhibit increased solubility in water and kinetics of complexation with the divalent cation compared to the alginate precursor.