The Effectiveness of Moringa oleifera Seed extract as a BioCoagulant for Mine Waste Water Treatment

Abstract

Mine wastewater usually requires treatment before it is discharged into the environment. Over the years, the volume and quality of wastewater generated and discharged into the environment by mining and minerals’ industries have remained critical issues due to the status of environmental standards and stringent discharge regulations. Coagulants used in mine wastewater treatment are often expensive and pose health risk to humans and the environment at large. Therefore, the use of natural substitutes which have low or no harmful effects in treating mine wastewater is considered an effective step towards protecting the environment. The effect of Moringa oleifera (MO) seed extracts as bio-coagulant in mine wastewater treatment was explored. The study was carried out using a conventional jar test apparatus with moringa oleifera seed extracts as coagulant at different stock concentrations (5, 10, 15 and 20 %). In each treatment (T1, T2, T3 and T4), 1000 mL of mine wastewater sampled from a large scale mine was contacted with 5-50 mL of MO for corresponding ten beakers. The results showed that addition of the bio-coagulant generally led to a significant decrease in the turbidity as well as the metal ions (Fe, Cu, Pb, Cd, Co, Mn, Zn, Ni and Cr) concentrations. Moreover, there was an increase in the pH of the wastewater. However, the bio-coagulant had two opposing effects on TDS and EC, which was stock concentration dependent. Overall, all the residual values for parameters measured were within (WHO) acceptable limit. These results suggest that moringa oleifera seed, a natural coagulant, is a viable substitute to synthetic and inorganic coagulants in mine wastewater treatment.