The purification of natural coagulant extracted from common bean on IRA 958 Cl anion exchange resin

Abstract

Natural coagulants are of organic nature and can increase the organic load of treated water and thus, they require purification in order to remove compounds that do not have coagulation activity. In this work, natural coagulant was extracted from 50 g L-1 of ground common bean with 0.5 mol L-1 NaCl. Proteins from this crude extract were precipitated by addition of ammonium sulphate. After the precipitation, separation and resolution of proteins, further purification was performed using the anion-exchange resin Amberlite IRA 958 Cl in a batch process. Partially purified coagulant eluted with 2 mol L-1 NaCl solution achieved the highest coagulation activity of 53.3 % at a dose of 1 mL L-1 although it contained the lowest amount of proteins, but a slightly lower coagulation activity of 49.8 % was achieved at more than 5 times lower dosage of the same fraction. The organic load in treated water when the purified fraction was applied as coagulant was almost 4 times lower than in case of the crude extract as coagulant.

Keywords

• proteins
• coagulation activity
• water clarification
• organic load