DIRECT SAND FILTRATION FOR SUSPENDED SOLIDS REMOVAL FROM ALIAKMON RIVER WATER

摘要

The removal of suspended matter in water is of great importance in water treatment. The efficient reduction of the suspended matter reduces also the risk of microbial contamination. This work deals with the determination of the optimum operational conditions for the efficient removal of suspended solids from Aliakmon River water, a surface water that will be supplied to the greater area of Thessaloniki. Three commercial coagulants were tested, namely Al_2(SO_4)_3, PACl and FeClSO_4. The efficiency of the coagulants was assessed on the basis of quantitative removal of suspended solids. Particle counts and UV absorbance measurements were analyzed in both raw and filtered water. The treatment efficiency was compared using particle measurements. FeClSO_4 could not significantly reduce particle count below 500 particles/mL at all conditions of this work, while PACl and Alum performed better. The most cost-effective coagulant has been PAG, which at a dosage as low as 2.5 mg Al/ resulted in less than 200 particles/mL at pH 7.5 and in less than 100 particle /mL at pH 7.