Question

8.7 Ferric sulfate is available as a commercial coag- ulant and is popular at removing turbidity and color. The chemical reaction for its addition to water is Results of a jar test to determine the optimal coagu- lant dose are provided below. The initial water sam- ple has a pH 6.5, turbidity of 30 NTU, and alkalinity of 250 mg/L as CaCO Ferric Sulfate dose, mg/L |5 1015 | 20 Turbidity, NTU 25 151 5 1 0.92 (a) What is the optimal mass of ferric sulfate you would need to purchase every day to treat 1 x 10 gallons/day to a turbidity below 1 NTU (assume 100 percent purity of the coagulant). (b) Do you have to add alkalinity to the system? If so, how much (in concentration units as mg CaCOs/L)?

Answer 1