The research focuses on the behavior of laboratory bench-scale filters that receive low-turbidity raw water. The filters have different configuration in terms of materials type, materials size and thickness. These filters operate under in-line and direct mode of filtration with different doses of alum and coagulant aid.
A total of 200 filter runs were conducted. Statistical methods had been used in the determination of best configurations of tried filters. Analysis of variance (ANOVA) and Duncan multiple range test had been employed for this purpose.
The results showed the superiority of filters operating under direct filtration mode compared to those of in-line filtration mode. It was thought that flocculation played a role in this result. Fine sand media of 0.56 mm E.S appeared to surpass the coarse media due to more trapping of impurities at pore spaces. The effect of coagulant aid addition was detected to act positively only with capping media filters, where an improvement in performance did occur. However, such improvement was low and did not justify importation of anthracite coal and coagulant aids and add an economic burden.
Keywords: Filtration modes, Filtration, Water turbidity, Water treatment.