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.

Coagulant proteins identified in Mustard: a potential water treatment agent

“…The thermo-stability of the coagulant protein is in accordance with previous studies conducted on Moringa seed (Ghebremichael et al 2005) and also the case of red bean, sugar maize and red maize (Gunaratna et al 2007). Similar properties have also been described in crude extracts, as well purified proteins of Vigna unguiculata and Parkinsonia aculeata seeds, where the coagulant protein around 6 kDa was found to be thermo-stable (Marobhe et al 2007b).…”

“…), sugar maize and red maize (Zea mays sp.) (Gunaratna et al 2007), Jatropha curcas (Pritchard et al 2009;Abidin et al 2013), Nirmali seeds (Strychnos potatorum) (Babu and Chaudhuri 2005), chestnut and acorn (Š ćiban et al 2009) and Cassia angustifolia (Sanghi et al 2002) has been reported. Although several natural materials are reported to be potent coagulant agents, the usage has not become widespread, probably due to limited knowledge and scientific reports on point-ofuse technology (Yin 2010).…”

A review on common vegetables and legumes as promising plant-based natural coagulants in water clarification

“…In fact, the diluted protein extracts showed improved coagulation activity that was lower compared to M. oleifera. Gunaratna et al (2007) also discovered that the protein coagulant was stable at elevated temperatures beyond 85°C with 30 % enhanced activity, but its turbidity removal remained fairly low, which is undesirable for the treatment of drinking water.…”

Decentralized Treatment of Grey Water by Natural Coagulants in the Presence of Coagulation Aid

“…A number of effective coagulants from plant origin have been identified: Nirmali [8], Okra, red bean, sugar and red maize [9], M. oleifera [10], ManilkaraZapota and a natural coagulant from animal origin; chitosan. The higher coagulant efficiency of natural coagulants allows more active colloidal aggregation and more consistent floc than with synthetic reagents, so that the necessary quantity of product is reduced and also the associated costs.…”