Abstract

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 their RE for some of the parameters treated The inorganic coagulants ferric chloride ferrous sulphate and alum showed no significant difference P 0 05 in the removal of COD while the organic coagulant MOS was significantly different at P 0 05 from the inorganic coagulants Over all Alum showed to be a better coagulant than other coagulants in reducing the physiochemical parameters of leachates while MOS is a suitable substitute for alum It was also observed that there was no significance 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