天然凝集剤<i>Moringa oleifera</i>によるカオリナイト粒子の凝集沈殿に水質が与える影響 Influence of Water Quality on Turbidity Removal by Coagulation with <i>Moringa Oleifera</i> Seeds

<i>Moringa oleifera</i> (<i>M. oleifera</i>) is one of the most widely spread <i>Moringa</i> species that grows quickly in the tropical belt. The objective of this study was to investigate the influence of the aqueous pH, initial turbidity of the synthetic kaolin turbid water, ionic strength, and humic substances on the efficiency of the <i>M. oleifera</i> coagulant. The experimental results showed that the coagulation efficiency was significantly enhanced by the presence of divalent cations such as Ca²⁺ or Mg²⁺, and slightly enhanced by lowering the aqueous pH from 9.0 to 4.0. It was also found that fulvic acid did not significantly affect the coagulation efficiency, while the initial turbidity and humic acid did. <i>M. oleifera</i> coagulant was effective for synthetic waters of an initial turbidity of 290 NTU. However, turbidity removal was not observed when the initial turbidity was lowered to 45 NTU. The presence of humic acid significantly increased the coagulant dosage required for turbidity removal. These obtained experimental observations were then used to discuss the influence of the water quality on the dominant coagulation mechanism.<br>