Optimization of the dose of calcium lactate as a new coagulant for the coagulation–flocculation of suspended particles in water Original Research Article

In this study, calcium lactate is proposed as a coagulant–flocculant. The operational conditions for efficient removal of suspended solids from water were optimized by use of a central-incomplete 33 design, to evaluate the effect of the calcium lactate dose (between 2 and 10 g l− 1), pH (between 5 and 7) and initial sediment concentration (between 4 and 16 g l− 1) on reducing water turbidity. It was found that within the ranges tested, the greatest reductions of turbidity were achieved with a moderate concentration of calcium lactate at pH 5. After 2 h treatment with calcium lactate the turbidity of water was reduced to 77–88% of that in the untreated control. Moreover 6 g l− 1 and 2 g l− 1 of calcium lactate reduced the water turbidity from 300 NTU to 2.5 and 5.5 NTU respectively after 18 h of treatment at pH 5. For short treatment times, the most important independent variable was the concentration of sediment, whereas for longer treatment times, pH was the most important variable.