Reduction of Turbidity in Waters Using Cassava Starch as a Natural Coagulant.

Currently, the purification of raw water is relevant due to its scarcity in some regions of the world. The objective of this work was to reduce the turbidity of raw water by using cassava starch as a natural coagulant. Starch was extracted from cassava for the coagulation-flocculation tests that were carried out using a response surface type experimental design. The response variables were turbidity, colour and pH, the intermediate variables being the initial concentration of the sample, speed and time of centrifugation, cooling time, stirring speed and coagulant concentration. It was established that by adding 250 mg/L of coagulant and with a speed of 40 rpm, a higher percentage of turbidity elimination is achieved. Similarly, starch does not add or remove colour to raw water samples, being within the range used and considered acceptable for use following Decree 1575 of 2007 for drinking water. Under the conditions established during the jar test, the turbidity removal percentages were higher than 70%. Therefore, cassava starch could be used as a natural coagulant. [ABSTRACT FROM AUTHOR]