Coagulation of turbid wastewater with an active component extracted from Moringa oleifera seeds

Abstract

ABSTRACT The oil and carbohydrates contained in the Moringa oleifera seeds (MO) are two parameters that inhibit its coagulant potential. Oil extraction and protein purification are therefore necessary to improve its performance. The extraction process to recover the maximum oil yield was carried out using the solvent chloroform: ethanol C: E in a ratio (3:1). At a temperature of 100°C, the yield was higher than 44%. Purification was carried out by salting-in the protein with 1 M NaCl combined with ethanol precipitation and heat treatment. Analysis of the protein powder by the Kjeldahl method revealed 92% pure protein and 14% nitrogen; energy dispersive X-ray (EDX) analysis revealed high percentages of carbon (45%) and oxygen (39%). Scanning electron microscopy (SEM) showed a porous surface, and X-ray diffraction identified a crystalline phase of protein. The isoelectric point of Moringa oleifera protein (MOP) is in the range of pH 6.5–7.5 and its zeta potential varies between −19 mv and + 25.49 mV. It indicates a lower level of dispersion stability, implying a high capacity for protein agglomeration and flocculation. By reducing the zeta potential of water from −16 mv to −1.18 mv after treatment without modifying its pH, the Moringa protein has proven its ability to destabilise organic colloids. Moringa protein as a coagulat aid is effective for high turbidity wastewater with removal up to 86.78% and DOC removal up to 56.52%. The study reveals that coagulation with Moringa protein is a cost-effective alternative since it reduces the quantity of coagulant and time required for wastewater treatment.