EVALUATION OF THE EFFICIENCY OF MORINGA OLEIFERA AS A NATURAL COAGULANT OF ORGANIC MATTER IN WATER
Water for human consumption must have microbiological, physical and chemical characteristics that meet drinking standards, that is, free of pathogenic microorganisms and contaminants. For this, several treatment steps are necessary, including coagulation, flocculation, sedimentation, filtration and disinfection. Aluminum sulfate is an efficient chemical coagulant used on a large scale in the coagulation/flocculation/sedimentation stage; however, it presents some risk level to health and the environment, since several studies have shown the association of this metal with Alzheimer's disease, and the sludge produced in this stage is not biodegradable and needs to be treated to be discarded or reused. Based on the life cycle impact assessment for the treatment processes with Moringa oleifera and aluminum sulfate, and the analysis of reduction of apparent color, turbidity, alteration of pH and alteration of dissolved organic carbon, in samples of raw water prepared by mixing peat and distilled water, and treated with saline extract from Moringa oleifera seed, and with aqueous aluminum sulfate solution in various dosages with different amounts of product, it was possible to conclude that the viability of using Moringa oleifera as natural alternative to the chemical coagulant aluminum sulfate. The first achieved 85 ± 2% color removal and 96.2 ± 0.2% turbidity removal, without changing the pH and dissolved organic carbon, against 72 ± 3% color removal and 86.1 ± 0.8% removal of turbidity, without alteration of the dissolved organic carbon, but with a pH reduction of around 36% for aluminum sulfate. Moringa oleifera also managed to reduce by up to 2.4 log (CFU mL-1) (99.6%) the concentration of the bacterium Escherichia coli after 72 hours of rest, with a dosage of 80 mg L-1. As for the environmental impact categories, Moringa oleifera also obtained advantages over aluminum sulfate in terrestrial ecotoxicity (ET), non-carcinogenic (human) toxicity (TNCH) and global warming (AG); the latter with a value of -74 % for alternative GC4, 8 % for aluminum sulphate; its negative value represents carbon sequestration up to this stage of its life cycle.