Evaluation of dewatering performance and physical-chemical characteristics of iron chloride sludge

摘要

The arsenic removed from drinking water generates a residue which is toxic. The aim of this study was to analyze the physical and chemical factors in the thickening and dewatering of sludge produced in As(V) removal by coagulation-flocculation process. The critical process variables associated with the removal of As(V) from water and sludge production were evaluated on experimental design. The optimum conditions were: pH 7.20; dosage: FeCl_3 34.37 mg/L and polymer 0.89 mg/L, settling solids 7.59 mL/L and final As(V) concentration 0.003 mg/L. Subsequently, the FeCl_3 sludge was characterized and the factors studied that influence in the dewatering performance: Specific Resistance to Filtration (SRF) with a minimum value of 6.29.10+12 g/cm and Filtration time (Ft) of 107 s. Regarding moisture distribution sludge is comprised 75% mainly interstitial and free water.