Screening and evaluation of natural coagulants for water treatment

Abstract

In developing countries many people are forced to drink turbid water and as a consequence many children are dying related to water borne diseases. Hence there is a need for inexpensive and easy methods to purify drinking water. The objective of this research is to screen different plant seeds to find a primary natural coagulant able to reduce the turbidity of the drinking water. The protein from 21 different seeds was extracted with water and salt solution and coagulation properties in synthetic clay solution were studied. The crude extract of Moringa oleifera (MO) showed the same coagulation activity as that of alum. The protein from red bean, sugar maize and red maize were promising in having coagulation activity, compared with a known coagulant protein from MO. These seeds were selected and purified to homogeneity with fast flow Sepharose ion exchange chromatography and the properties of the purified proteins were characterized. The characteristics of these coagulant proteins are different from MO protein based on molecular weight and ionic determinations. The coagulant proteins were temperature tolerant and can withstand temperature of around 85 °C and maintain the coagulation activity. The seeds identified as a coagulant source could be used as an alternative to chemicals for drinking water clarification.