Influence evaluation of the functionalization of magnetic nanoparticles with a natural extract coagulant in the primary treatment of a dairy cleaning-in-place wastewater

Abstract

Abstract Improving primary treatments is of utmost importance, which can be achieved by reducing the necessary time for the process, accomplishing a better quality of the treated wastewater and reducing the residues that may be generated. In a dairy industry, most of the effluent is provenient from the sanitation system, usually cleaning-in-place (CIP). This work investigated two organic coagulants, Moringa seeds extract (Mo) and nanoparticles (NP) of iron oxide functionalized with the Moringa extract (MoNP) as an alternative for the primary treatment of an effluent coming from the CIP of a dairy industry. The aim was to achieve a better treated effluent in a reduced time, since there are evidences that the NP with sedimentation under the influence of an external magnetic field can reduce settling times and result in a more compacted sludge. Different salts were examined for the Mo preparation as well as its combination with magnetic NP. Biotoxicity tests were performed with the objective of analyzing whether this extensively used seed and the NP could affect the flora using Lactuca sativa seeds as test organisms. The functionalization of the magnetic NP with the Mo prepared with calcium chloride (CaCl2) proved to be a good alternative for the primary treatment of dairy CIP wastewater since it provides about 90% of turbidity removal in a reduced sedimentation time (7 min compared to 60 min when Mo is used alone) and NP can be recovered from the sludge (which, by itself was already more advantageous since it was more compact) and refunctionalized to be reused. Besides, neither the Mo nor the MoNP increased the ecotoxicity of the treated effluent when Lactuca sativa seeds bioassays were conducted.