Statistical evaluation of the coagulation-flocculation process by using Moringa oleifera seeds extract to reduce dairy industry wastewater turbidity

Abstract

The use of coagulant aqueous extract obtained from M. oleifera seeds in the integration of coagulation/flocculation processes and membrane separation proved to be an environmentally friendly alternative for wastewater treatment from the dairy industry. Three saline solutions, KCl, MgCl2 and CaCl2, were tested to extract the active component from Moringa seeds. The greatest statistical effect on turbidity removal was attributed to the initial pH of the effluent, according to the t-Student at the 5 % significance level. The maximized turbidity and color removals were 96.8 and 90.3 %, respectively, at pH 11 and 300 mg L−1 of the coagulant extracted with CaCl2 0.9 mol L−1. Nanofiltration indicated that previously flocculated organic matter particles were reversibly retained by the membrane. Total fouling was only 35 %, resulting in 98 % recovery of the initial water flow, and a reduction in color, turbidity, COD, calcium, and hardness of 99.5; 98.9; 89.1; 85.5 and 85 %, respectively.