Coagulation–flocculation process with ultrafiltered saline extract of Moringa oleifera for the treatment of surface water

• Moringa oleifera is capable of treating 75 NTU turbidity surface waters.
• The concentration of saline extract was an asset in decreasing the volume of the coagulant.
• Ultrafiltered coagulant produced water with the lowest organic load.

The objective of this study was to obtain a natural coagulant from the Moringa oleifera seed that was able to reduce the contamination of surface water with initial turbidity of 75 NTU without increasing the organic material in the water treated. The parameters evaluated were color, turbidity and compounds that absorb light UV254nm, dissolved organic carbon (DOC) and reduction of specific absorption of UV254nm (SUVA). For this we used the saline and aqueous extraction processes of coagulant followed by ultrafiltration. In this work the dosage of coagulant was used in terms of concentration of protein coagulant, allowing greater reproducibility and reliability of results. The saline coagulant had a better performance in the removal of color (89.15%), turbidity (88.75%) and compounds with UV254nm absorbance (75.93%), with low DOC concentration in the treated water and with 38% less SUVA concentration, when compared to that by surface water. A decrease in the volume of the concentrated coagulant needed for such results should be underscored. In fact, only one half of the volume was required when compared to non-ultrafiltrated coagulant. The above directly affected DOC in the treated water which was less for concentrated saline coagulant (4.01 mg/L) when compared to non-concentrated saline coagulant (8.39 mg/L). High efficiency in water treatment, reduced volume of coagulant and decreased concentration in organic matter in the treated water, especially with regard to SUVA, open new perspectives in the use of saline coagulant of M. oleifera as a natural coagulant for the treatment of supply water.