Comparison of the Effectiveness of Moringa oleifera (Moringa) Seeds and Strychnos potatorum (inguin) Seeds as Natural Coagulants for Turbid Water Purification

Abstract

Lack of quality drinking water is a burning and life-threatening problem especially in the dry zone in Sri Lanka. Many inorganic coagulants and synthetic organic polymers widely used in conventional water treatment processes. Recent studies have indicated a number of serious drawbacks linked to the use of those coagulants and flocculants. Therefore, there is a rising interest to develop cost-effective, easier and environmental friendly processes of water purification with the usage of natural coagulants. Therefore, the present study is focused to study the effectiveness of water extracts of Moringa oleifera (Moringa) seeds and Strychnos potatorum {Ingini) seeds in turbid water purification. The dry matter content, protein content, fat content and ash content of the seed powder of M. oleifera and seed paste of S. potatorum were determined. The coagulation activity was assessed by the jar test using natural low, medium and high turbid water. The water samples were treated with seed extracts of M. oleifera and S. potatorum and the physicochemical markers evaluated were pH, turbidity, total solids, total dissolved solids, total suspended solids, electrical conductivity and the biological marker was total plate counts. The turbidity was reduced up to 92% by the dosage of 200 mg/1 of M. oleifera and it was effective for low turbid water (Turbidity of 25-35 NTU) than the S. potatorum, The turbidity was reduced up to 95% by the dosage of 300 mg/1 of M. oleifera and it was effective for medium turbid water (Turbidity of 40-50 NTU) than the S. potatorum. The turbidity \yas reduced up to 97% by the dosage of 4 mg/1 of S. potatorum and 95% turbidity reduction was observed by the dosage of 400 mg/1 of the M. oleifera in high turbid water (90-120 NTU). The optimum dose of different seed extracts revealed a pronounced efficiency for removing TPC, TS, TDS and TSS. There was no effect on pH and EC of the water samples treated with these natural coagulants. M. oleifera was effective for low turbid water than the S. potatorum while both coagulants were effective for high turbid water. However both natural coagulants, better water turbidity removal efficiencies were noted at high turbidity compared to low turbidity.