Ferric chloride is an effective coagulant for the removal of suspended solids and appreciable amount of Chemical Oxygen Demand (COD) in sewage. Treatment of sewage by ferric chloride produced highly voluminous sludge which was resistant to dewatering process. Lime improves dewatering of ferric sludge by reducing specific resistance and increasing the compressibility characteristic of sludge depending on the dosage of conditioners. Flyash was also concluded as an effective conditioner due to a decrease in the specific resistance of sludge. On the other hand, addition of flyash decreased the compressibility coefficient of sludge.
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