Treatment of the textile wastewaters by electrocoagulation: Effect of operating parameters on the sludge settling characteristics

This paper deals with treatment of industrial wastewaters by electrocoagulation technique, with emphasis on settling process. The influence of electrode material, current density, pH, treatment period on the sludge settling characteristics has been investigated. The wastewater issued from textile industry is characterized by its high suspended solids content (SS0), its high turbidity (NTU) and a fair chemical oxygen demand (COD). The wastewater treatment process consisted in a preliminary electrocoagulation step, followed by a settling step conducted without addition of flocculating agents. Sludge settling velocity after electrocoagulation was measured depending on the operating conditions. The data were employed to investigate the influence of the process parameters on the settling process. The sludge settling data were utilized to compare the efficiency of various empirical models for estimation of sludge settling velocity. Finally, the sludge aptitude to settling was studied in terms of sludge volume index (SVI) to determine the best operating conditions.