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.
