Valuation of oil extraction residue from Moringa oleifera seeds for water purification in Burkina Faso

This study is on the reuse of the residue generated by a Moringa oleifera oil extraction plant. The residual oil cake produced during the process of oil extraction retains the positively charged protein of the M. oleifera seed, which is the active component in the process of 15 attracting and capturing suspended particles in waters. Such coagulant–flocculant properties give rise to the elimination of turbidity in the process of water purification. In the cases studied, it has been demonstrated that the same amount (100 mg/L) of aluminum sulfate coagulant and M. oleifera coagulant is required to reduce water turbidity to levels within the International guidelines (<5 NTU). A life cycle analysis (LCA) is also presented in which the 20 coagulant obtained from M. oleifera is compared with conventional chemical coagulants. The energy consumption per kg of aluminum sulfate (Al2(SO4)3) produced is almost 40% greater than M. oleifera-based coagulant. Furthermore, carbon dioxide (CO2) emissions associated with alum are 80% higher than those of the M. oleifera-based coagulant. In addition to turbidity removal, with lower energy consumption and reduced CO2 emissions, the coagulant 25 derived from the residual oil cake does not provoke any alterations to water pH or conductivity and, therefore, does not require any additional readjustment of these parameters.