Global Journal of Human-Social Science, B: Geography, Environmental Science and Disaster Management, Volume 22 Issue 3

Figure 3: Effects of varying pH at constant coagulant dosage on COD Figure 4: Effects of varying pH at constant coagulant dosage on TSS c) Effects of Different Coagulant Concentrations in Coagulation Treatment To observe the effect of coagulant dose, the experimental runs were conducted at different doses (1, 2, 3, 4 and 5 g/L). The percentage removal efficiency at each dose was compared. Depending on the coagulants, the optimal dose varied with the various coagulants used. FeCl 3 removal efficiency for heavy metals ranged from 55% to 85% (Figure 5), this is in line with the reported work of Lee et.al . (2012) where FeCl 3 was reported to remove 75% of Pb. Amuda and Alade (2006) also gave a report in this range. FeCl 3 removed Cr better than Pb and Mn. FeCl 3 was not as efficient in removing COD, the value ranged from 19% to 40% (Figure 6). Other studies also reported low RE of FeCl 3 for COD (Ibrahim et.al ., 2012; Lee et.al. , 2012). The optimum dosage for FeCl 3 was determined to be 3 g/L, the RE dropped beyond this dosage. FeSO 4 removal efficiency for heavy metals ranged from 65% to 85% as shown in Figure 7. FeSO 4 also removed more of Cr when compared to Pb and Mn, following the trend of FeCl 3 . It was also not as efficient in removing COD, the value ranges from 21% to 37% (Figure 8) this was in accordance with the work of Ibrahim et.al . (2012). FeSO 4 also had optimum dosage of 3 g/L. Additional concentration above the optimum dosage reduced the efficiency of the coagulant. © 2022 Global Journals Volume XXII Issue III Version I 59 ( ) Global Journal of Human Social Science - Year 2022 B Abatement of Polluting Effects of Waste Dump Leachates using Different Coagulants