Water treatment works using coagulation/flocculation in the process stream will generate a waste sludge. This sludge is termed as,ferric, alum or lime sludge based on the coagulant primarily used. The work in Adana, Turkey uses ferric chloride. The potential for using this sludge for the treatment of corrugated paper mill wastewater by coagulation has been investigated. Two main parameters were investigated namely chemical oxygen demand (COD) and total suspended solids (TSS). The sludge acted as a coagulant and low COD and good TSS removal efficiencies were obtained. The optimum condition works at pH of 6 and a sludge dose of 500 mg/L. The efficiency of sludge was also compared with alum and ferric chloride for the paper mill industry wastewater.