عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Coagulation-flocculation is one of the most important processes for water treatment, commonly used all over the world. The use of synthetic polymers known as “Polyelectrolytes as a coagulant aid is now wide spread in water treatment plants. Tehran’s “Jalalieh WTP” has been using an anionic polyelectrolyte under the trade name of “Magna Floc LT25” for a number of years MagnaFloc LT25 (MF-LT25) is a synthetic coagulant with high molecular weight, produced in granular and powder form. The application of this coagulant aid is known to be most effective if injected to water after addition of main coagulant (Ferric Chloride in Tehran’s WTP). However the use of synthetic polymers in treatment of drinking water has always been under question due to extract of MO seed contains proteins soluble in water which have high coagulating properties. This pilot scale study was performed to compare the coagulating properties of seed extract of MO to MF-LT25, The tests were carried out on Tehran’s raw water in Jalalieh treatment plant. Several turbidity ranges such as 5, 20, 100, and 200 NTU were used representing real seasonal turbidities of influent water to treatment plant. Optimum concentration of the coagulant and coagulant aid was determined within water pH values of 6, 7 and 8, using common “Jar Test” technique. The extract of Moringa Oleifera seed in optimum concentration of 10, 14,25,35 mg/L and optimum pH of 8 is capable in removal of 96.5, 97.4, 98.5 and 99% of water turbidity range of 5, 20, 100, and 200 NTU respectively. Under similar conditions, MF-LT25 removal efficiency were found 97, 98.1, 98.4 and 99.4% of water turbidity range of 5, 20, 100, and 200 NTU at optimum concentrations of 0.015, 0.02, 0.025, 0.03 mg/L respectively. The results also showed that the extract of Moringa Oleifera seed is a powerful coagulating agent, at alkalinity pH values, and is more effective for high turbid waters. It compared well with synthetic polyelectrolyte as a coagulating agent. Due to possibility of its production locally, and its excellent properties it could be considered as a potential substitute for more expensive imported polymers such as Magnafloc- LT25.