Behavior of turbidity, pH, alkalinity and color in Sinú River raw water treated by natural coagulants

Abstract

Natural coagulants were evaluated in saline Hylocereus cf. trigonus stems, gum exudate of Albizia saman, bark and seeds of Moringa oleifera and bark of Guazuma ulmifolia in raw water samples from the Sinu river with 56, 104, 200 and 301 Nephelometric Turbidity Units, and Jar tests were conducted to determine the performance removal turbidity of each coagulant, with doses between 5 mg/L to 60 mg/L. pH, color and alkalinity of the water samples were measured before and after treatment to verify the incidence of the coagulant in the purification process. For H. trigons, A. saman, G. ulmifolia and bark of M. oleifera, removal percentages ranged between 50% and 70% and up to 95% for M. oleifera seed. Greater coagulant activity was recorded for applied doses between 20 mg/L to 30 mg/L, independent of raw water turbidity. The pH and total alkalinity had no significant changes for the entire dose range, while the true color slightly increased with extracts of H. trigons, A. saman, G. ulmifolia and bark of M. oleifera, and decreased significantly with M. oleifera seeds to values lower than 5 CU, which was the extract with the highest in removing turbidity and color.