Abatement of Polluting Effects of Waste Dump Leachates using Different Coagulants
This study assessed the effectiveness of different coagulants for treating leachates before their release into the environment. Three inorganic coagulants (ferric chloride, ferrous sulphate and alum) and one organic coagulant [Moringer Oleifera seed (MOS)] were used in a jar test to determine the optimum pH and dosage for the coagulants. Raw and treated leachates were analysed for physiochemical parameters such as pH, chemical oxygen demand, Total solids, Pb and Cr. The optimum pH for ferric chloride, ferrous sulphate, alum and MOS was 7, 7,6 and 10 respectively. While the optimum dosage for each coagulant was 3g/L, 3g/L, 5g/L and 5g/L respectively. The analysis of the raw leachate sample showed that it was highly polluted (Dry season: COD – 3000mg/L, TSS – 2369mg/L, Cr – 0.075mg/L, Pb – 0.25mg/L and Mn – 0.29mg/L; Wet season: COD – 3000mg/L, TSS – 2369mg/L, Cr – 0.075mg/L, Pb – 0.25mg/L and Mn – 0.29mg/L).Coagulants removal efficiency (RE) for COD ranges from 12% to 41% with ferric chloride having the highest removal efficiency. All the coagulants were efficient in reducing the level of heavy metals in the sample leachate. The RE ranges from 55% to 95.6% with MOS having the highest RE of 95.6% for lead. The coagulants showed significant difference (at P 0.05) in the removal of COD, while the organic coagulant (MOS) was significantly different at P 0.05) in the removal efficiency of the coagulants in both dry and wet seasons. Seasonality has no effect on the effectiveness of the coagulants.
